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How to build model airplanes >> Cook ups, Build alongs, participation builds, what have you. >> Any Twin Cookup
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Message started by Tom Akery on May 31st, 2014 at 1:04pm

Title: Any Twin Cookup
Post by Tom Akery on May 31st, 2014 at 1:04pm
I'm going to take a chance and see if we can't get enough participants to have a twin cookup.  We've been talking about it on the Moonbat cookup and we've come close to finishing up the Moonbats.  So we'll be looking at new builds.  Some are such prolific builders that I can't keep up with them! 

I've been hooked by the Dornier Do 335-B8:
The B-8, the final B-series variant, was to be a two seat night fighter for which the M23 was the designated development prototype. The B-6 night fighter was to be based on the A-6 airframe. The B-7 was also to be a night fighter with an enlarged laminar flow wing with 441 square feet of surface area and 2000 hp DB 603 engines for which the M22 would have been the development prototype. The B-8 was to have been a high altitude night fighter which incorporated the Heinkel designed high aspect ratio long span wings with 463 square feet of surface area and powered by the DB 603 LA engines of 2000 hp. It would have carried the standard armament of 1 x MK 103 and 2 x MG 151/20 cannon. There is no evidence that any of these night fighter variants were ever built. Below shows an artist's rendition of how this aircraft might have looked.

My build will be based on the plans by Don Srull which I've modified to the larger wing and second cockpit for the radar operator.

So here's a thread for anyone who might like to join in and build any twin they wish. 
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Title: Re: Any Twin Cookup
Post by staubkorb on May 31st, 2014 at 1:13pm
With the flying season about to jump in on us (Mine has gone back into hibernation), we'll likely need a "longer" time-frame.  I'v got around 5 aircraft to consider for this endevour, but not to sure if I'l actively participate - still have to get my D.VII assembled :(.

Title: Re: Any Twin Cookup
Post by bigrip74 on May 31st, 2014 at 1:14pm
Well if you are going to stick your neck out I will also: I wish to attempt the Joe Ott plan for the Martin Maryland it just captures my imagination from my youth when I first built an Airfix version in 1/72 scale.

The plan is #41 in the Misc. Military Aircraft under the WWII section.
http://www.stickandtissue.com/cgi-bin/yabb2/YaBB.pl?num=1394076461/30
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Title: Re: Any Twin Cookup
Post by Tom Akery on May 31st, 2014 at 3:10pm
I'm for keeping this one open ended!  I don't see a time limit at this point because we've all got planes on the building board and I'd really like to finish off the Fury and the Moonbat before starting this twin.  So we'll go from here with the idea that it's open ended.  Finish date to be set later!
Tom

Title: Re: Any Twin Cookup
Post by bigrip74 on May 31st, 2014 at 6:03pm
I need a little help guy's, l have been studying the plans for the Maryland and while I can make out the dimensions for the fuse box (3/32) I am unable to determine if the ribs, leading and trailing edge are 1/16 or 3/32 also the same re: the stab, rudder, fuse formers, and the spars. If you would look at the plan and give me your interpretation it would be most appreciated.

Bob

Title: Re: Any Twin Cookup
Post by Tom Akery on May 31st, 2014 at 6:38pm
Bob...from the Plan Page there's a construction article and it give dimensions of the formers for the Kingfisher a High wing sport model.  It calls for 1/16 formers and ribs.   Most designers like to use the same or similar sizes for their similar span models.  So this might help in deciphering the Maryland plan.  I believe the Kingfisher is about 5ft span though and it use the above sizes for the formers and ribs. The formers and ribs for the Maryland might be the next size down around 1/32".

"The Plan Page" can be found Here
Here's an info page link: Click Here

modified 5/31 5:33 PST:  I found this thread on HPA Bob,  Looks like the formers in their kits were around 1/32" thickness Click Here
Tom

Title: Re: Any Twin Cookup
Post by bigrip74 on May 31st, 2014 at 6:41pm
Tom thanks for the info. I will do a little more research on this plan before cutting any wood.

Bob

Title: Re: Any Twin Cookup
Post by bigrip74 on Jun 1st, 2014 at 3:34am
I went to Hobby Lobby to purchase some Acrylic Gloss Spray and found a couple of hard 3/32 sheets of balsa. WOW! A local find that has not I have not been able to find locally.

I started the fuse box with that wood:


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Title: Re: Any Twin Cookup
Post by mitch j on Jun 1st, 2014 at 6:01am
Ok guys, I cant help myself......I'm in!! After the Moonbat, I've been looking forward to doing something a bit more....straight forward....simpler....less taxing on my poor little brain- & I think I've found it! I'm going to do Dick Howards 18 inch twin "Double Top". Its from Sept. 1987 Areomodeller (via Outerzone of course!). It looks fairly straight forward so we'll see how it goes!!

No holding you back Bob!! The Maryland will be a good looker I reccon! I've got plans for various WWII bombers that I thought about doing but I think I'll keep it simple this time! Better luck with this build mate!! I was just looking at your plan on Outerzone-interesting construction method, with round/oval formers slipped over the box fuse, then stringers on top. Looks like it will be quite strong! Interesting wing ribs too!(Looks like a nice step by step on carving a prop there as well.....hint hint.....!!)

Title: Re: Any Twin Cookup
Post by bigrip74 on Jun 1st, 2014 at 12:12pm
Mitch, I got your hint on carving the props :D. Have you heard of H. J. Towner and his plans? There are several twins that look nice:

Misc. Military / WWII / page 3, #44 / page 4, #49 #51 / page 5 #71

Bob

Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 1st, 2014 at 2:37pm
Mitch...don't know if Outerzone has the magazine article with the plan but the RCGroups posting has the article with it!  Click Here Post #417

Looks like a fun model and the article suggest adding a bay to the center section of the wing if not in embryo competition for better performance.  I look forward to seeing this one come together!

Tom

Title: Re: Any Twin Cookup
Post by Robert Hudson on Jun 1st, 2014 at 8:03pm
Maybe I'll go out on a limb and design my own twin  ;)  Something simple and non-scale.

Title: Re: Any Twin Cookup
Post by bigrip74 on Jun 1st, 2014 at 8:49pm
RH, glad to have you and it does not need to be scale just a twin. And I would love to see your design.

Bob

Title: Re: Any Twin Cookup
Post by mitch j on Jun 1st, 2014 at 9:44pm
Ha Ha just kidding Bob-what ever you do is just fine by me mate!!

Tom, thanks for the link to the Double Top build notes-they were not on Outerzone. Always handy to have though!

Title: Re: Any Twin Cookup
Post by mitch j on Jun 1st, 2014 at 9:47pm
My mistake Tom-just had another look-the build notes are there!! (Cant see for looking!!) Thanks anyway!!

Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 1st, 2014 at 11:02pm
Mitch...no problemo...I didn't check Outerzone so I'm glad they included it.  I just did a quick skim of the article.  Look like a really fun model and a great introductory build for twins.  Can't wait to see it come together!

Tom

Title: Re: Any Twin Cookup
Post by mitch j on Jun 3rd, 2014 at 7:48pm
G'day all;

Made a start on my Double Top. Only 2 fuse frames & the horiz. stab so far but after the Moonbat, its good to be doing something that is coming together a bit quicker! More pics soon!

Cheers!!
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Title: Re: Any Twin Cookup
Post by bigrip74 on Jun 3rd, 2014 at 8:32pm
Mitch, I took a look at the plans for your Double Top and I was impressed wish I had seen them last year. Your start looks so clean as do all of your builds nice job [smiley=thumbsup.gif] this will be a great looking airplane and one I will keep up with to see how you trim her.

I did a little more on the Maryland, but had to stop until I find some more hard 1/16 and 1/32 to continue on the fuselage formers (1/32) and the wing ribs, and stab. Still not sure if I will use 3/32 or 1/16 on the wing spars.

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Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 4th, 2014 at 12:55am
Boy, you guys are really progressing and I'm no where near starting!  Still waiting for materials to finish up the Moonbat! 

Your builds look great.... Bob, I see that you've mastered building the fuselage sides on top of each other.  That fuselage is really thin!

Mitch...that Double Top will be done before you know it!  Looks good so far!

Tom

Title: Re: Any Twin Cookup
Post by mitch j on Jun 6th, 2014 at 3:53am
G'day all;
Got a bit more done on the Double Top-the fuse is finished & I'm working my way through the wing. So far its a fairly straight forward build, & I'm really liking this cracked rib method! I put in a few more cross pieces in the sides of the fuse too-it seemed a bit flimsy to me but I'm happy with it now. I have a 4 day break from work so I should get a bit more time to build! Anyway here's a few pics-more soon!!

Cheers!!
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 6th, 2014 at 10:14am
Mitch...looks like your making great progress.  What's the size of your longerons on the fuselage?  The bones look fantastic so far!
Tom

Title: Re: Any Twin Cookup
Post by bigrip74 on Jun 6th, 2014 at 1:18pm
Mitch, the fuse is looking good and I notice that you use poster tacks to align the two sides while gluing the cross members neat trick I never thought of that they seem sturdier than my flimsy T-pins. As for the four days off from work I hope they are productive and restful.

I was hired yesterday after a seven year stint (lay off, school, move) and was getting pretty use to being a lazy airplane building bum ;D

Title: Re: Any Twin Cookup
Post by mitch j on Jun 6th, 2014 at 7:17pm
G'day guys;

Tom, it's all meant to be made from 1/16 square as usual, but the stuff I'm using at the moment probably is closer to 3/32. A touch heavier I know but I dont compete & it is a twin so power shouldnt be an issue. (....well they're my excuses & I'm sticking to them!! Ha Ha!!)

Bob, I find the poster pins really useful for keeping things flat (due to their large head area), especially where 2 or 3 sticks join in 1 spot. They also save having to try & stick pins through thin trailing edges etc or using 2 pins & a piece of scrap to hold thin stuff in place. (I still use normal pins to keep it all in line though.) I probably got the idea to use them from someone here's build pics!
(P.S. Dont worry Bob, I work 5 days a week & I'm still a lazy airplane building bum-& proud of it!!)

Cheers guys!!

Title: Re: Any Twin Cookup
Post by mitch j on Jun 9th, 2014 at 1:20am
Another update on the Double Top-a quick moc-up of the story so far. The wings still need dihedral & narceles  (in progress at the moment) but so far so good! Need to start thinking about props soon too I suppose. The plans give options for tricycle or tail dragger landing gear-I'm leaning towards tricycle, just for something different!

More pics soon!!
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 9th, 2014 at 11:20am
Mitch...the bones look great so far!  As fast as you're going on this project you'll be finished before I even get started! :D ;)

Looking forward to the addition of the nacelles and dihedral.  This is a very nice looking model. 

Tom

Title: Re: Any Twin Cookup
Post by mitch j on Jun 9th, 2014 at 5:33pm
Thanks guys!

cd, looking at your Senator & the Gym Dandy, you would have no problems with this bird! Actually, I am thinking it would probably be a good project for a first twin scratch build, being generally quite straight forward (so far!).

Tom, I think I might have a go at the sort of props you made for your Moonbat so I dare say I'll have a few questions when I get that far!! (You have been warned ha ha!!)

Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 9th, 2014 at 6:23pm
Mitch...no problem, ask away! [smiley=thumbsup.gif]

Tom

Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 10th, 2014 at 4:21pm
I hope to pull off the Do 335 B-8 high altitude night fighter with extended wing.  It will be based on the Don Srull plan with enlarged wing the whole design enlarged to around 36 inch span.  Here's a link to SFA showing a Srull Do335 build and Chris Starleaf's Dumas kit modified to the long wing night fighter.
Click Here EDIT: Due to SFA closing down, this link no longer  available.

I'll be starting on this one as soon as I can get the CAD enlarged plan printed out.

Tom

Title: Re: Any Twin Cookup
Post by bigrip74 on Jun 10th, 2014 at 8:46pm
SORRY Guy's I have been busy filling out more paperwork and soaking up as much lazy time as possible before starting that job on Monday.

@Mitch: I am loving the Double Top and your usual clean building process.

@Tom: those photos of the Do 335 were interesting and wonder at the 36" monster that you are preparing to construct.

Bob

Title: Re: Any Twin Cookup
Post by mitch j on Jun 19th, 2014 at 4:27am
G,day all;
Work on the DoubleTop has slowed down a bit lately (work, sport, kids etc....you know how it is!), but its now ready for tissue. So far its 14 grams without props, rubber & tissue. I'm glad I went with the tricycle landing gear too-I think it looks cool !! Anyway, here's a few mocup pics. Now to start thinking about what tissue to use!!

Cheers for now!!
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 19th, 2014 at 11:22am
Mitch,

Totally understand the demands of life.  Family first, job second, then the hobbies as time permits!  The Double Top is looking great!  Nice set of bones.  I'm looking forward to seeing the scheme you put on this one!  I know it'll be nice!
Tom

Title: Re: Any Twin Cookup
Post by bigrip74 on Jun 19th, 2014 at 7:18pm
Mitch: she is looking good. What kind of motor are you thinking of using?

Bob

Title: Re: Any Twin Cookup
Post by mitch j on Jun 24th, 2014 at 7:40am
G'day all;
An update on the Double Top-got all the tissue on, its starting to look like a plane now! Since I took these pics, I've shrunk the tissue, installed the windows, & had a go at making some bearings for the wheels. They seem to have worked-she rolls like a real tricycle now!!

Bob, as far as motors go, I only have 1 sort of rubber (about 3/32 x 1/16 I think) so I will use that with 5 1/2 inch props.(Something else to start thinking about!)

Still got a little bit to go but its getting there!
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 24th, 2014 at 10:51am
WoW Mitch, 

Great job with the tissue.  Love the scheme!  Is the small pinstripe tissue or marker?  This is a fantastic looking model.  If she flies as good as she looks you're in for some great flying!!! [smiley=thumbsup.gif]

Tom

Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 24th, 2014 at 3:02pm
Well got things started on the Do335 B8 extended wing high altitude night interceptor. (Boy that was a mouth full, in future referred to as the Arrow)LOL ;D :D ;)

While the keels (dorsal, ventral and horizontals) are drying I made a template for the sliced ribs.  They'll be of 1/16 balsa.  The template is made of wooden hobby sticks (look like tongue depressors).  I cut the pattern from the plan and used that to make the template.  It's for a "Clark Y " airfoil.  You'll notice I used two sticks so I could make an offset of 1/16 inch on the backside of the template to allow making accurate cuts from 1/16 sheet balsa. 

To make the first cut I start at the bottom of the sheet which then allows me to get 1/16" thick ribs.  For the shorter ribs I cut the trailing edge off the rib to proper size. Allowing the wing to keep the proper airfoil through the span.

I'm looking forward to this build now!

Tom
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Title: Re: Any Twin Cookup
Post by bigrip74 on Jun 24th, 2014 at 8:04pm
@Mitch: beautiful tissue job, she looks like a real flier to me.

@Tom: VERY INTERESTING looking airplane, do you have the prop/drive all figured out?

I will post some photos of the Maryland this weekend I promise. Time seems to be at a premium now with work.

Bob

Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 24th, 2014 at 8:22pm
Thanks Bob...glad things are going well with you and the new job.  Priorities are important and we look forward to Maryland pictures.

I made some ribs for wing construction tomorrow hopefully if I can find some good wood at the only place it's available here in this little town.  I forgot to anchor the balsa sheet before cutting the ribs.  So the first rib slipped and the trailing edge was a bit too thin.  I'll use it for a shorter rib in the construction process where I need to shorten a rib.

Here's some pics explaining my sliced rib process. 

A picture I did of my proposed scheme from Photoshop.

Tom
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Title: Re: Any Twin Cookup
Post by staubkorb on Jun 25th, 2014 at 5:49am
Nice start on the Do, Tom.  Which plan are you using?  Your take on the rib slicer is interesting, and should work fine.

I've tried a number of various ways to slice ribs accurately - all with mixed results - but I may try your method next ;D.  If that way doesn't satisfy me, then I'll prolly order one of the custom slicers from Mike Kirda (indoor F1d flier) that is basically a modified Jones stripper (IIRC) and not expensive at all.  The only thing is that the end user has to make up his/her own template - understandable in that there are hundreds of airfoils.  He only makes them when there is a call for more than just a couple (I think he does them in batches of five).

Still haven't fully decided on which twin I'll end up doing, but the A-26 Invader keeps creeping up to the top of the pile ::).  I'm really trying NOT to start a new model till I get the D.VII finished (it's getting there!).

Pete

Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 25th, 2014 at 10:28am
Thanks Pete...

As for the template for slicing ribs.  Make sure the balsa sheet is anchored some way to allow pressure on the template to the sheet so it doesn't slip or slide away from the sheet as you make the cut.  I also make several light cuts rather than trying to cut completely thru the balsa in one cut.  Seems to work better and less slipping of the template.

I fully understand the reasoning of waiting till the DVII is completed.  I don't like to have too many models in the construction process.  Looking forward to the completion of your DVII.  Looks good so far!!!

My build will be based on the plans by Don Srull which I've modified to the larger wing and second cockpit for the radar operator using CAD redraw.  Wingspan will be 28 inches. Just trying to match the wood I had on hand.

Tom

Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 26th, 2014 at 10:20pm
Made some more progress today on the fuselage.  I made a lattice jig for the dorsal and ventral keels to hold them in place while the formers are added.  I then added some stringers.  I still have some stringers to add and just noticed that I installed the F-13 former upside down.  Tomorrow I'll rectify this problem. :-[ ::) :-/ :'(

Here's some pics of the work done today.

Tom
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Title: Re: Any Twin Cookup
Post by terryman on Jun 26th, 2014 at 11:43pm
Tom,

Very nice so far.  What did you use to hold the keels onto the ladder?

Terry

Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 27th, 2014 at 12:43am
Just a small dab of Duco cement thinned 50/50 with acetone. I used a very small amount to tack the upright to the two 1/4X7/16 inch rails.  I used my machine squares to make sure the upright were at right angles to the rails.  I marked placement of the uprights by laying the rails just below the side view of the plans to make sure the uprights didn't overlap any formers.  The upright were 1/16 X 3/8 X 5 inches.  To remove them after the keels and several stringers were applied, I brushed on some acetone and let it set a bit and then brushed on some more and let it set.  This loosened the duco and allowed me to gently twist off the rails with a little help from a single edge razor.  The same procedure for removing the upright from the keels as well.

Worked very well and held things in alignment till ready to remove them before adding all the stringers. Just don't put on too many stringers before you remove the jig or it will be very difficult to remove.

Tom

Title: Re: Any Twin Cookup
Post by bigrip74 on Jun 27th, 2014 at 8:22pm
Tom, I like your jig the photos almost gave me how to do it. Thanks!



Bob

Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 27th, 2014 at 9:03pm
Thanks Bob... I seem to be able to get a straighter fuselage with this method rather than building it "Clam Shell"  (half at a time then adding the other side).

Got the F-13 former flipped over today and add the remaining stringers.  Picture to follow later.

Tom

Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 27th, 2014 at 10:39pm
Here's the pictures of the fuselage with all the stringers in place.  I've still got to do the planking on the nose back to the cockpit to allow me to put in the gun troughs.  I've also started the cowling.  Pictures tomorrow.

Tom
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 28th, 2014 at 11:33am
Here's my cowling construction.  I got a bit eager after laminating the two front discs together and glued up the stringers and a rear disc. The laminated discs need additional clamping so I added the hair clamps/pins.  While the glue was still tacky I aligned it all with machine squares and weighted it while it dried.  Once dried I added the nose ring clamped with clothes pins. Here's pics of the process. 

Tom
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 28th, 2014 at 6:21pm
Time to call it a day building.  Getting tired of fitting planking between stringers.  Got the cowling done as far as rough sanding.  Still need to fill the grain and finish sand.  Lots of planking on nose to complete and then sand and fill and finish sand.  But making progress.

Didn't stage any pictures today too lazy....so pardon the messy board.

Tom
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Title: Re: Any Twin Cookup
Post by staubkorb on Jun 29th, 2014 at 10:25am
NICE job on the nose lip shaping! Hand sanded or did you put the cowl on a turntable?

Title: Re: Any Twin Cookup
Post by terryman on Jun 29th, 2014 at 10:33am
Tom,

Tom the nose piece looks quite uniform in shape.  Are you hand holding while sanding or somehow jigging it to something like a drill chuck and sanding while spinning?

Terry

Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 29th, 2014 at 11:35am
Thanks guys...all hand sanded this time around.  Used 220 grit first and then a fingernail file for further sanding.  Still have to use 320 or 400 to finish sand.  Then seal and more 400. 

Tom

Title: Re: Any Twin Cookup
Post by bigrip74 on Jun 29th, 2014 at 11:37am
Tom: All I can say is WOW! Great job[smiley=thumbsup.gif]on the nose/cowl piece. Thanks for the tip and how to photos.

This will be the 3rd. try to post pics on my Maryland, I do not like Windows 7 and the features that use to be second nature are no longer available to a Neanderthal like me ;D

SO! here is the 4th. try to post pics after using an older (Vista) computer.

Fuselage pics:
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Title: Re: Any Twin Cookup
Post by bigrip74 on Jun 29th, 2014 at 11:39am
THE WING AND STAB:
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 29th, 2014 at 11:44am
Bob...looks great.  I have to say that's a very nice looking fuselage.  There's just something about a bones shot that really inspires.  You're tempting me to add the Maryland to my "To Do" list!  What's the length of this fuselage.  Awesome job.  As for the Windows 7 you'll get used to it after a bit.  Give yourself some time to adjust to the differences and where everything is found in the new program.

WoW Bob...you were posting while I was posting....you've been a busy boy!  Wings look great also!  Well done!

Tom

Title: Re: Any Twin Cookup
Post by bigrip74 on Jun 29th, 2014 at 12:15pm
Tom, I use HPA"s photo reducer to get the pics below 400kb, but on the Window 7 the process does act as with earlier versons. It gives an Esite to the photo description, not just the revised photo and S&T does not recognize the photo. So I go to my mothers old laptop to perform the photo conversion just as always with success.


Bob

Title: Re: Any Twin Cookup
Post by terryman on Jun 29th, 2014 at 1:13pm
Bob,

How's the new job?  It looks like you are finding a balance between working and building.

The wing ribs are something I don't think I have seen before.  Are the tops cut from sheet stock?  Looks strong, light and a nice curve for the air-foil.  What do you think of the method, do the parts fit together OK?

Terry

Title: Re: Any Twin Cookup
Post by bigrip74 on Jun 29th, 2014 at 3:05pm
Terry the ribs are in between cracked and what Tom is using for his build.

The bottom is from square stock and the top is cut from sheet then placed over the spars just like cracked ribs.

I've seen this method on plans and others builds before, but this is my first. Not sure what to think yet since I have not figured out the wing to fuse attachment.

The job is interesting and my build time is like yours imagine, an 1/8th of what I had before.

Bob

Title: Re: Any Twin Cookup
Post by Tom Akery on Jun 30th, 2014 at 2:29pm
A bit more progress...planking done.  Filled some cracks before any sanding with light weight spackle.  Moving along nicely.  Getting ready to build wings.  I like wings, easier to build and keep straight!!!   ;D ;)
Most of the fill will be sanded off in prep for sealing the grain.
Tom
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 1st, 2014 at 1:29am
Finished sanding and filling the nose planking.  Spent a long time scalloping the formers. Whew, the more the stringers the more the scalloping to do!  Filing with a rattail file and then finish sand the scallops with various shaped sanding blocks. 

Then built the horizontal stab panels using 3/32 leading and trailing edges and 1/16 ribs and spar.

Here's the latest pics... I'm starting to like this model.  Always have liked the shape and this looks to be a real fun and challenging model to get to fly. 

Weather here is starting to warm up and it seems that late afternoon early evening the winds are starting to calm down.  So I hope to get something into the air soon.
Tom
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Title: Re: Any Twin Cookup
Post by mitch j on Jul 1st, 2014 at 2:29am
G'day all;

A couple of fantastic builds there guys!! I haven't had much time to keep up with things lately (not much time for building either....),so its really good to see heaps of progress!

Bob, just try & keep this one away from heavy objects ok? And you've found another method of rib construction-very interesting!

Tom, the pin striping you asked about is just part of the tissue design. I just tried to be careful which bit I used. (You may be able to see the next lines at the top of the fuse behind the side windows!)

Keep up the good work guys!!
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 1st, 2014 at 1:14pm
Mitch...great job in choosing the tissue.  I've gotta keep my eyes out for some tissue like that.  Great idea and use of the tissue!  Well Done! [smiley=thumbsup.gif]

Tom

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 2nd, 2014 at 7:05pm
Got the vertical and horizontal stabs completed today.  Finish sanded them and added horizontal stab anchors on each side of the fuselage. Still have to work on the wing root area.  As usual for me, had to mock up the components.  Here's the pictures.
Tom
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 2nd, 2014 at 9:18pm
Surfing the net for Do335 info and found this site.  RCSCALEBUILDER.COM  it's a free site to join, and they build way too big and complicated models for my S&T builds.  There are some interesting construction techniques we can use...but more it's just inspiration!  Some of the guys are talking 120 inch span for a Do335.  That's more Bill Parker size models!!!!  Get better Bill!!!

You have to join before you can view the site posts.  Click Here

A couple of awesome Do335 Pfeil "Arrow's"!

Tom


Title: Re: Any Twin Cookup
Post by cdwebb on Jul 2nd, 2014 at 10:12pm
I haven't done much posting, but I've been keeping tabs on you guys. Ambitious and talented!

Bob, the Maryland is a beauty of a plane and I'm itching to see more of it come together. On the board it kinda reminds me of an A-26, another one I think is just a gorgeous airplane. I know you're short of time these days, but stay at it as much as you can. I lovin' it!

Mitch, the striped tissue trick is ingenious! That thing really looks GREAT!! You definitely have a talent for building and it shows on every build. Neat and clean every time!

The 335 is coming right along. So far, what I see is work, work and more work. Enough of it that I don't think I'd have ever attempted it, but you're making it look easy, Tom. How big did you say it is? It looks huge in the photos!

Very nice work all around, guys!! 8-)

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 2nd, 2014 at 11:04pm
CD...the wingspan of the Do335 Pfeil is 28 inches fuselage is also long at 19 inches less spinners.
She's a big one, but not as big as Bill Parker's birds.
It has been a lot of work, thanks for the complements!
Tom

Title: Re: Any Twin Cookup
Post by mitch j on Jul 6th, 2014 at 1:45am
G'day all;
Had a go at some of Toms "plastic container" props.  I used Toms pics & descriptions from his Moonbat build as a guide & I guess I'm fairly happy with the results. I did the hubs a bit different (drilled holes in a small block for the blade shafts), & I cut the blades from a 2kg yogurt tub (all I had on hand at the time),so there's not a lot of camber in the blades. I guess a smaller diameter container will give a "tighter" curve...if you know what I mean! I enjoyed this method of building the props so it probably wont be the last time I try it!
Anyway, heres a few pics minus rubber. I still want to get hold of some tiny washers for the prop bearing set up, so I haven't bent the hooks in the shafts yet.
Nearly time to start putting it all together-more pics soon!! 
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 6th, 2014 at 1:56am
Mitch did you remember to offset the blades on the cup 15 degrees to the left, tip from the hub?  The standard is 15 to 17 degrees from vertical with the narrow part of the cup down toward the hub of the blade.
Look pretty good. 

You might want to take a look at these threads in the prop section:
All You Need to Know About Can Formed Props: Click Here

Laribee "MIL" Minimum Induced Loss Propellers: Click Here

Koutny Scale Prop construction: Click Here
Mister Koutny uses the iron to get the curvature in the blades the yogurt cup supplies at the 15-17 degree offset.

If you've read these threads already, I apologize! ::) ;D ;)
Tom

Title: Re: Any Twin Cookup
Post by mitch j on Jul 6th, 2014 at 4:35pm
G'day Tom,
Yeah mate, I drew a vertical line straight up the side of the tub, drew a 15 deg. offset line & drew out my blade on that (the offset line went the other way for the other prop). I wasn't sure on blade shape so I just drew a template for 1/2 a blade & flipped it over for the other half. There is still some curve in the blades but the tub I used is 6 inches dia.-more like a small bucket really! These props were a bit of a "see if I can" type thing-the next one I try, I will maybe use a medium size soft drink bottle or a large plastic cup, & try a more "traditional" blade shape. All in all though, an interesting little project!!

Cheers mate!

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 6th, 2014 at 4:52pm
I tend to use the Laribee prop blade shape unless looking for a more scale appearance.  There are templates for various diameters of props.  I usually go for the 1.5 to 1.7 pitch shape in the length appropriate for the proper diameter (blade being radius of the prop arc less hub diameter).

Tom

Title: Re: Any Twin Cookup
Post by mitch j on Jul 6th, 2014 at 7:02pm
Great idea about using the Laribee props as templates-I must remember that! I assume that the darker lines are for a "standard" thinner or wider blade-with the wider blade generating more thrust-is this correct?

Thanks Tom-more good advice as usual!!

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 6th, 2014 at 7:50pm
Mitch... in the Laribee article page 48 column 3 discusses the shape of the blades and suggestions on what lines to follow.  I usually adjust my lines to allow clearance of the cowling. 

Another suggestion on these plastic blades, is to use a dowl or bamboo shaft and with a razor saw cut a slot for the blade to fit into, because some plastics refuse to adhere to any glue.  You may then drill small holes through the dowl/bamboo and pin with toothpics to hold the blades in the dowl/bamboo.

Sometimes you just have to experiment to see what works with the plastic.

Tom

Title: Re: Any Twin Cookup
Post by bigrip74 on Jul 6th, 2014 at 11:12pm
Mitch, I liked the props  before you painted them they were phsycodelic.

Bob

Title: Re: Any Twin Cookup
Post by mitch j on Jul 7th, 2014 at 2:15am
Thanks Tom-any more obvious & it would have bit me! Musta bin too busy lookin' at the pretty pictures!!

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 7th, 2014 at 5:04pm
As I do from time to time when I can't build (had the grandsons over for a couple of days) I decided to re-read some of the FAC (Flying Aces Club) newsletters.  I found an article by Don DeLoach, No Secrets "One Flier's Approach to Better Performance - Part 1" from the Sept/Oct 2012 issue.  Very interesting.  I decided to check out his approach with the Do335 B-8 Pfeil. 

Here's an excerpt: This is in regards to scale aircraft models.

Dispelling the Myths
"Set the CG at 25-35%.  We've all heard that one, but it is often a trap for mediocre performance in FF Scale.  There's a simple antidote to this: the Bill McCombs Tail Volume Coefficient/Starting C.G. formulae.

TVo = stab area/wing area x tail moment arm/wing average chord 
C.G. (%) = 16+[TVo x 36]

Bill was one of Don's early mentors and a Princeton-educated engineer for Vought Aircraft.  What is TVo? Put simply it is the measure of a horizontal tails effectiveness as a function of it's tail moment arm (length from wing L.E. to stab L.E.) and wing average chord.  TVo is hughely important, because it explains why a "Scale model with a 25% stab" is too vague.  A 25% stab on a P-51 mustang...or a Pilatus Porter? The two airplanes have vastly different moments that result in a very different tail effectiveness.  One may need a C.G. at 29% while the other needs to balance at 47%. The C.G. difference greatly affects flight trim and behavior.

The "magic" TVo number I have found (through much trial and error) for FF scale is 0.65.  When plugged into the McComb C.G. formula this results in a C.G. of 38%-- well aft of the clichéd "one-quarter to one-third" point.
With a 0.65 TVo almost any scale model can be made to fly well with not a lot of fuss (assuming good fundamentals like warp free well aligned surfaces, adequate dihedral, proper fin area and methodical trimming in calm weather).  With TVo less than 0.65 models become quite a bit harder to trim for competitive flight times. I've found. (written by Don Deloach)

Turns out my Do 335 Pfeil is right there.  TVo= 0.65  Wing area= 104 sq in   Avg. wing chord =3.72"  wingspan 28"  Tail Moment Arm = 10".  My C.G. is right on the same location as noted on the plan...   Aparently Don Srull did his homework in designing this baby! 

There is so much more in this article on Dihedral, Prop & Motor combination, etc.
On Decalage
Positive Incidence in the Wing or Negative in the Stab
This is a rabbit trail that just leads to confusion. I have models with 0 degrees of wing incidence that fly as good as models with 3 degrees  wing incidence. All that matters is the relative angles of the wing and stab -- known as decalage. In a typical FF scale model with TVo between 0.65-0.75 decalage is going to be about 2-3 degrees, but that's trivial because you're not ever going to actually measure it.  Just set the C.G. per the TVo, start your test glides, and tweak the stab or wing angle until you get a floating glide.  That's it. From this point you know you have a model with adequate pitch stability with C.G. in the right place that is safe to start power-trimming.  You should never need to trim anything but thrust angle from this point.
(Don DeLoach)  from same article.  I'll be giving this a try on my trimming of the Pfeil!

Tom
P.S. Math is not really my thing but with a couple of the wing area calculating sites and I was in business. Check out the National Free Flight Society (NFFS) Click Here

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 7th, 2014 at 8:31pm
With this wing being 28 inches the magnet board was too small.  So I pulled out the old pin board.  It's a 2 X 4 foot wooden board base with a 2 X 4 foot celotex ceiling tile.  Works great and I think I like it better than the magnet board.  There are pluses to both boards.

I was able to complete the wing panels and join them together.  Dihedral is set at 1.5 inches.

Here's the pics of the wing constructions so far.  I'll complete the wingtips with foam to keep things light.

Tom
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 7th, 2014 at 10:42pm
Once the wing dried I couldn't resist a mockup of the fuselage and wing... left the ventral fin off...
Tom
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 8th, 2014 at 12:09pm
Bob,
Found this three view of the Maryland while surfing the net. 
Airpages Click Here

Tom

Title: Re: Any Twin Cookup
Post by bigrip74 on Jul 8th, 2014 at 7:16pm
You guy's are really going to town. Love what you both are building, I have slowed down quite a bit with learning the job.

Tom: thanks for the 3 view it makes me think twice about the nose glass now.

Mitch: I cannot wait to see you fly your twin since it looks like you will finish first.

Bob

Title: Re: Any Twin Cookup
Post by mitch j on Jul 9th, 2014 at 4:07pm
Well the Doubletop is basically finished- justneed to find some tiny washers for the prop shafts & add rubber. Weighs 27 grams without rubber. This was a good fun build-I'm glad I went with the tricycle landing gear, I like how it sits!

Bob, the weather is pretty crappy here at the moment so I wont be doing any flying any time soon. In a few months when the weather picks up (hopefully!), I can get out & try. Besides this one & the Moonbat, I still haven't tried the rebuilt Hemiptere yet either!!

Ok...what next....? Too many choices!! I know, I'll do this one....no, maybe I'll do this one...or this one...or...or...
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 9th, 2014 at 7:09pm
Mitch...the DoubleTop looks fabulous!  I love the blue and white.  Easy to find in the tall grass and a great looker too.  Front view reminds me of the DHC Twin Otter.  You've out done yourself.

As for what to do next.  I completely understand.  Too many planes not enough time or money!!! ;D :D ;)

I got some more work done on the Pfeil "Arrow"...

After doing some reading and getting advice from some more experienced with the Do335 I decided to enlarge the horizontal stab a bit more than on the plans.  Re-sanded the cowling at the rear to better fit the fuselage and rigged the ventral fin to be a knock off with short very flexible thin wire.  I drilled the holes with a pin drill and hardened the holes with Cya making sure to clear the hole by running a wire down into the hole with the Cya keeping things moving all the time so it wouldn't set the wire.  Worked out well hardened the balsa leaving a nice hard tube for the wire. 

I also cut out the radar operator's (RIO/WSO's) cockpit and installed an instrument panel. From drawings looks like a gun sight on top of the panel (yet to be installed on the model)

As always couldn't resist another mockup.

Tom
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Title: Re: Any Twin Cookup
Post by mitch j on Jul 9th, 2014 at 7:29pm
Thanks Tom, I guess it was a fairly straight forward build & as usual, the camera is probably being a bit kind!
That bird of yours is really starting to look the goods mate! With the nose all shaped & the tail done you can really tell what it is now. I must remember the "CA hole strengthening" trick too-very handy for avoiding breakages!

With regard to "time & money", I think once we are set up with basic tools & stuff, rubber powered S&T scratch building is quite a cheap hobby really- a few sheets of balsa seems to go a long way!!

Cheers !!

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 9th, 2014 at 8:04pm

mitch j wrote on Jul 9th, 2014 at 7:29pm:
Thanks Tom,
With regard to "time & money", I think once we are set up with basic tools & stuff, rubber powered S&T scratch building is quite a cheap hobby really- a few sheets of balsa seems to go a long way!!
Cheers !!


I've done the plastic route, the RC Models with several radios and planes and S&T is definitely the better route.  I agree a few sheets of balsa and some tissue and your ready to go!...  Sky's the limit!

Tom 

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 10th, 2014 at 7:29pm
On to what I call the "fiddly bits"...
Landing gear & sockets, Nose/prop blocks, canopy plugs, instrument panel detailing, spinners etc.

Today it was nose block and landing gear.  The nose block shows the offset extension to the spinner.  It is moved up on the real aircraft to align with the prop shaft and allow a cooling radiator below it within the cowling.  I haven't noticed if this is the same on the FW 190-D9.

Still need to add the prop shaft bushing to complete block.  Still have a prop block for the rear prop to go.

On to the landing gear.  The main struts are fashioned from bamboo skewers approximately 1/8" diameter.  I used paper strips to show edges to the oleo strut sections.  Still need to paint so wheel axles are removable till detailing is complete.  Just found out the mover didn't move my plastic container that had my paints in them.  They are not allowed to pack liquids.  Wish they'd told me before I moved from Texas.  I knew I had one box missing.  So got to restock the paint supplies.   

I made paper tubes for sockets in the wing and nose.  The socket mounts of balsa blocks off the top end of the main gear strut sockets.  The nose gear socket is open at the top. A paper ring around the strut hold it from going further into the socket.

Here's some pictures of the gear and mockup... sorry like looking at the bones all mocked up! ::) :D ;D

Oooops I see I got the main gear twisted around.  The struts should be on the outside with the wheels on the inside.   ::) :-[ :'(

Tom
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 19th, 2014 at 8:00pm
Well my ship didn't come in but my rowboat did so I was able to replace some of my paints lost in the move, Allowing me to finish up the detailing of my landing gear.  And to make the ejection seat (one of the first in active service during WWII).  Also worked on a foam pilot, and got the base coat of paint applied.  Still lots of detailing with the paint to be done, right now his head looks like a black blob...

So here's a couple of pics of the "fiddly bits" done today...Landing gear struts painted, Ejection seat carved from foam and painted with headrest, and my foam pilot!

Tom
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 20th, 2014 at 5:52pm
Well got some more done on the Do335.  Pilot and RIO completed and made the mold for the Nose Spinner so I just had to put them all in their places.  Here's a few pictures...
Tom
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Title: Re: Any Twin Cookup
Post by mitch j on Jul 20th, 2014 at 8:03pm
Good stuff Tom!! Those pilots look cool!! Something else I need to try one day......!

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 21st, 2014 at 4:10pm
Making progress even though it doesn't look like much.  I made some progress on the wing saddle area, finished the molds for both front and rear spinners.  Just had to mockup again to see how things look.  Left out the pilots that I spent two days working on but that's ok. 

Here's a few pictures.

Tom
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Title: Re: Any Twin Cookup
Post by bigrip74 on Jul 22nd, 2014 at 7:02pm
Tom: I now see that the wing is a little different than usual, how strong is it?

BTW! [smiley=thumbsup.gif] Nice job on the fiddly stuff.

Bob

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 22nd, 2014 at 11:14pm
So far it seems as strong as my normal construction.  I'm expecting the tissue to firm it up as is usual when covering standard structures! 

Thanks Bob [smiley=thumbsup.gif]

Tom

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 25th, 2014 at 6:11pm
Well got some tissue applied today.  Decided to use black on the bottom and white Esaki on the top.  I have found with the tissue the wing is very strong and am pleased with it!

I'll apply the Krylon and then crank up the airbrush for color and the camo scheme. I did get some warping in the horizontal stab.  I'll respritz and pin to the board to see if that will cure the problem.

Tom
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Title: Re: Any Twin Cookup
Post by Fliegerhorst on Jul 26th, 2014 at 10:02am
May I join in on this cook up?

Looks like too much fun! I wonder if there are model plans for a Chance Vought Cutlass??  ::)

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 26th, 2014 at 10:47am
Fliegerhorst...Yes! and Yes [smiley=thumbsup.gif]

In the plans section, page two, post#25, you'll find the Chance Vought F7U Cutlass Click Here

Or there's the NoCal kit from Kittyfritters available from him check the NoCal builds section: Click Here

Kittyfritters has gotten this Cutlass flying very nicely. Be sure and read up on his design & build and view his videos. Great stuff! It can be flown inside or outside as well.  Either one would be a fun build. 

Tom

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 26th, 2014 at 3:46pm
Got some more "fiddly bits" done.  I made the ventral radiator scoop for the rear engine from pink foam with a balsa lip to protect it on possible hard landings.  I'll cover the foam with tissue to smooth out the foam for paint finish later.  I did paint one engine carb scoop with acrylic paint to see if this would seal the foam.  It does but leaves a bumpy surface.  So I'll have some sanding to do on that scoop.  I also made the radiator exhaust doors for the rear engine from two laminations of bond paper.  I found this technique on HPA and their EDF board.  You laminate the two layers over a shaped balsa form and microwave it for 10 sec.  Cooks the moisture out of the glue leaving a very nice firm part (whatever the shape) and holds the shape better than just plan paper. 

I got some wrinkles back from the moisture in glue as I mounted the engine carb scoops on the right side.  I didn't think there was that moisture in the glue?!

I also got the canopy plugs carved.  Just need to seal them and prep for vacuforming the canopies.  Can't find my vacuform box from the move. Bummer! May just have to plunge form them or make a new box like I believe it was Mitch did from the plastic container.

Here's some pictures of the progress.

Tom
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Title: Re: Any Twin Cookup
Post by Fliegerhorst on Jul 27th, 2014 at 11:09am
Wow Tom!

That ant eater is looking really good!

In doing a build, there are several things that I don't know---where do you guys get your wood? What kind of paper do you cover with? How do you transfer patterns to the wood? I tried using the copy paper-laquer thinner way on to bass wood for my B-36 but it didnt work well.

Also where do you get a Jetex engine nowadays??? I'd like to do the little Cutlass that has full bulkheads. :)

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 27th, 2014 at 11:36am
Fliegerhorst...

1. If you can find a good local hobby shop you can purchase the balsawood  there.  If not there are a couple of online hobby sources for balsawood.  Check the Supplies board for some good links. Click Here

2. The tissue paper is Esaki tissue made in Japan.  It's available from various sources.  Volare/Shorty's Basement, Easy Built and several others. They also offer "Domestic" tissue made here but is not always as strong and able to be applied wet.

3. The way I transfer the patterns to the balsa is use gluestick on the back of the paper pattern and apply it to the balsa sheet. (I understand there is a new gluestick for scrapbooking that is removable, I haven't tried it yet. I thing Target has it)  Then cut out the pattern leaving wood edge around the pattern and sand to edge of the paper.  Then peal off the paper and mark the balsa piece with it's proper notation! Important to remember to mark the balsa!

4. Jetex, to my knowledge, isn't manufactured anymore.  I've heard of some people finding them on Ebay but you aren't always sure what you're getting.  They are used or NOS that someone hasn't used yet (very rare to find).

5. When you say "full bulkheads" I'm not sure what you mean?  The Cutlass plan in the plan section "Jets" is designed for Jetex, but this isn't for internal jetex motor, Most jetex motors were placed in a recessed belly mount.  Similar to rapier powered models.  Do to the lack of these power sources most modelers are redesigning them for mini or micro EDF (Electric Ducted Fan) power sources.  Check out the EDF thread on the FJ4 Fury build.  I'm learning about this genre myself. Click Here
Hope this is helpful.
Tom

Title: Re: Any Twin Cookup
Post by terryman on Jul 27th, 2014 at 2:50pm
Tom,

Maybe you already said, but what sort of foam are you using and where do you get it?  How does it compare to shaping and finishing very light balsa?  You have seemed to settled on a preference here, I like what I see.

Terry

Title: Re: Any Twin Cookup
Post by bigrip74 on Jul 27th, 2014 at 6:37pm
Tom: the Do is really taking shape and the minute details are amazing. Cannot wait to see her fly.

I broke down and started building the nacelles and plan on building the left wing this coming weekend. I was tired of work interfering with my free time >:(

Bob

Title: Re: Any Twin Cookup
Post by mitch j on Jul 27th, 2014 at 6:42pm
Looking good Tom-up to your usual high standard!! Like terryman, I'm interested in the foam too. The laminated paper/microwave thing sounds interesting as well. Always something to learn!!

Fliegerhorst, where I live, the local toy store is the only place I can get balsa. Only a basic selection but I make do. (A 3 hour drive for anything else...not if i can avoid it!)
As far as transfering patterns, I cut them out to shape & trace them out lightly with a fine ballpoint pen. Some of the smaller, & skinnier/longer bits I pin down but usualy I just hold them down with my fingers. Then just cut out & sand till the line dissapears. Might not be the easiest way for you, but it works for me!

Bob, you gotta find time for your hobbies mate- it keeps us sane (i think!!)

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 27th, 2014 at 7:44pm
Thanks fellas for the kind words...

Bob...glad to hear you're back to building.  I look forward to this model coming together.  Looks awesome so far. 

Terry...the foam is 1/2" insulation foam that comes in 4X8 foot sheets. One sheet is more than a life time of supply.  Around $10 a sheet.  Not to bad.  I got mine at Lowes and had them cut it in half so I could stick it between the seats of the car in the back.  No truck!   It's a very close cell foam that shapes and sands easy.  It will dull a blade really quickly.  When the blade gets dull it starts to drag through the foam and doesn't cut cleanly but rips and tears the foam and that's really bad.  I use a razor knife with the breakable blades I get from the dollar store.  Usually comes with several blades and replacement blades pack of 5 or so usually hangs next to it for a buck!  When it starts to drag...toss it and put in another one.  It's really very light and often times lighter than a balsa part.  I try to hollow out all the parts before mounting them.  Keeps them even lighter.  You will need to cover the foam with something to seal it before any painting.  I as explained in the earlier post, cover with tissue and white glue.  This seals the foam and protects it from some paint that would eat it.  But be careful, some paint, even after the tissue covering will eat the foam if applied to heavily at once!

The foam is really good for complicated shapes....

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Jul 28th, 2014 at 11:53am
Just to keep the juices flowing and to give myself a "rest" from that blasted D.VII, I've started to cut wood for a twin or two.  Haven't quite decided which to actually start building, nor will it be an integral part of the cook-up.  It IS, however, directly related - being a twin, so I'll be posting my (slow) progress here.

I just have too many outside projects and personal issues to commit myself to any cook-ups.

The models coming together here are GREAT and I hope the weather starts to get sorted to see some of them take to the air in the "How's It Flying" board :)!

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 28th, 2014 at 12:22pm
Pete...great to have you aboard.  We look forward to your input!  What birds are you considering? Take your time and no pressure on this cookup for completion!

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Jul 28th, 2014 at 12:53pm
The A-26 "Invader" from the Comet plan, that I'm modifying (adding lightness) and /or the RUTANGO in 75% scale (Bill Brown plan).

I'm leaning more toward the 'Tango, since it is not a "scale" plane and the only curves are in the nose and rudders.  It's the same model that Don McLellan did at 13" span for the QB cook-up on SFA.  He has not been able to get it sorted yet, but I believe that the problem is directly due to Mr. Reynolds.  I'm hoping that a larger model (17") with its correspondingly larger canard will be easier to sort.

The A-26, as designed, uses solid bulkheads in the fuselage (= weight/mass).   I'm trying to rework the fuselage to a "box and fill-former" style.  I built the Comet kit back in 1990 to the completed "bones" state - even gluing it all together - and was surprised how seemingly light it was (didn't weigh it tho).  It didn't survive the next move  (ex decided to use it for kindling >:() and I vowed to build another.

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 28th, 2014 at 5:12pm
Both look like great choices.  I look forward to which ever plane you choose. 
Tom

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 28th, 2014 at 6:45pm
Got the Pfeil covered and wing mounted.  I used the section I cut out of the fuselage to close up the belly below the wing.  I secured the wing and then made the wing fillets out of bond/copy paper. I then leveled the fuselage and made a jig for mounting the horizontal stab panels.  Got the pilots mounted and the plug-in ventral fin.  Just need to seal the cowl, spinners, make the prop blades,vacuform canopies, then I'll be able to start painting.  Things are coming together pretty good so far. No major challenges so far.

Tom
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Title: Re: Any Twin Cookup
Post by bigrip74 on Jul 28th, 2014 at 8:46pm
Tom: the Do is coming along effortlessly in your hands [smiley=thumbsup.gif]. I really like the photos of how you applied the wing fillets.

Pete: the Comet A-26 was in my stash of 2 way back (1965) when I did not really know anything about building, but attempted it anyway with results we will not go into here ;). I will watch your build with interest.

Mitch: that twin of yours should be ready to fly now, got any pics?

Bob

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 28th, 2014 at 10:31pm
Thanks Bob...I meant to add that in applying the wing fillets...I start at the trailing edge cutting paper patterns till you get a fillet that you like. I then took the final pattern and traced it for the other side.  Don't forget that this is to be a mirror image of the first side. I used a bamboo skewer to roll the fillet on to pre-shape it.  I also spritzed it with isopropyl alcohol to make it more flexible.  Be careful it becomes fragile if too wet.  This allows me to get the compound curves needed for the wing/fuselage joint.  I then added the thin strip forward towards the leading edge, rolled and spritzed as above.  I then added a short piece to get the leading edge wrapped at the root. There needs to be a small slit on the fuselage edge of this last strip to make the sharp bend. 

I want to look into molding this piece in the future with laminated copy paper. Like the rear vent on this model.

Sorry if I got too long winded! :D ;)
Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Jul 30th, 2014 at 8:06pm
I've settled on the RUTANGO @ 75%.  The A-26 will take too long to get set up the way I want to build it - essentially a complete re-design of the fuselage...

Started with the rudders.  The plan is actually one of the ones that was not quite finished - no wood sizes specified or just how the canard was to be built (flat plate or cambered).  The rudders  are shown to be solid balsa, but I went with built-up ones (there are two of them).

One half of the canard is framed - flat bottomed and a CLG style airfoil on the upper surface - using the same layout that Don used on his.  You can get an idea of the layout HERE at reply #66.

Title: Re: Any Twin Cookup
Post by bigrip74 on Jul 30th, 2014 at 9:25pm
Pete, that is a neat looking airplane and one that would really look great in flight.

Bob

Title: Re: Any Twin Cookup
Post by staubkorb on Jul 31st, 2014 at 8:06am
75% RUTANGO

My confuser is giving me some headaches so any news or photos might be a bit delayed, but...

Some photos of what I've done...

The photo of the rudders ( there ARE two there) were built atop one another to get them as symmetrical as possible.  They'll get separated when I get ready for fitting to the airframe.  Some of the diagonals don't quite match up, but they are close enough for me - the weight and outline is what is most important.
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Title: Re: Any Twin Cookup
Post by mitch j on Jul 31st, 2014 at 10:51am
G'day fellas;
Tom, staubkorb, great looking builds guys (as usual!!) Good info on the wing fillets there Tom!
Bob, my Double Top has been ready to fly for a while now but, even though Australia (most of witch) has a reputation of being hot, dry, dusty etc, winter/spring in my neck of the woods is still crap for flying FF outdoors. Where I am, August/September is always windy......(which, by the way, is why I'm getting into kites.....well.....its still flying....!) Once summer gets here, I've got a few toys to try-the Moonbat, the Double Top, the Hemiptere, the Taube.....Wish me luck!!!

Cheers guys!!

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 31st, 2014 at 11:36am
Mitch...

You might want to check out the board on flying S&T Models as high speed kites... Click Here

This looks like great fun in those windy times of the year.  I'm seriously thinking about this for the area I've just moved to.

Tom

Title: Re: Any Twin Cookup
Post by bigrip74 on Jul 31st, 2014 at 7:31pm
MITCH:

I WISH YOU GREAT FLYING WEATHER FOR ALL OF THOSE WONDERFUL BUILDS. [smiley=thumbsup.gif]

Bob

Title: Re: Any Twin Cookup
Post by Tom Akery on Jul 31st, 2014 at 10:10pm
Pete...the RUTango looks great so far.  Really like the shape of the vertical stabs.  I was looking at Don's build on SFA but he didn't have props on it yet.  Is this a tractor or pusher configuration?  Guess I'll have to look up the plans on HPA.

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 1st, 2014 at 6:56am
The RUTANGO...

It's a tractor, Tom.  Don has a link to a flight test somewhere (I think), and towards the end of the thread he states:
Quote:
Lawn dart yes, or floaty going nowhere pancake special yes. 


I'm almost convinced that the canard at p'nut scale was/is just too small (Mr. Re #) and is also a simple flat plate (which SHOULD satisfy Mr. R).  There is also no CG indicated, meaning that it will be a "guess as you go" or an attempt at one of the CG calculators.


Title: Re: Any Twin Cookup
Post by Tom Akery on Aug 1st, 2014 at 10:00am
Pete...
I'd guess that at least the cg calculator would give a starting point to work from.  Very interesting design.  Just the unusual kind of plane that attracts my attention.  May have to add it to the "To Do" list! ;D :D ;)
Tom

Title: Re: Any Twin Cookup
Post by Tom Akery on Aug 2nd, 2014 at 1:14pm
Update on the Pfeil (Arrow)....
Got the canopies formed (gotta make a new vacuform box my original didn't survive the move). I tried a different process.  I used the clear plastic of the 2 liter soda bottles and cut off the bottom end and using wood dowels and clamps I held the form inside the bottle and used a heat gun to shrink the bottle around the mold. Took a couple tries but got the Pilot's canopy done and it turned out pretty well.  The smaller canopy for the RIO's station I used a smaller soda bottle 16 oz.  It turned out pretty well also. 
I'm using Aleene's tacky glue (available at Walmart) to attach the canopies.  You can see it white in the pictures, but it dries clear. 

I also completed the nose block using a KP adjustable nose block.  We'll give these a try to see how they work making adjustments at the field.  Found a "Clocking" article for these on the net to preset the nose block for 2 degrees down 2 degrees left to start.  We'll see how thing go from there.

I will mask off the canopies panels before painting so the panel lines will match the fuselage colors.

Tom

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Title: Re: Any Twin Cookup
Post by bigrip74 on Aug 2nd, 2014 at 8:11pm
Pete: I am enjoying your photos on the construction and use of that magnet board, you and Tom make it look so easy.

Tom: those canopies look so crisp and clear on your Pfeil . I was going to ask how you kept them clear before I reread the post. My canopies are a little milky (Pete had stated in the past that it may be due to the heat). I may need to try your method. Went to Hobby Town to obtain some wood (help me!) and other building supplies, spoke with an RCer who stated that there was a soccer field fairly close to my apt. that would be a good area to try my airplanes. WOW! I may have a place to go that is close and fly this stack of unflown a/c.

I also gave a couple of guys at work an airplane and may have hooked one into building a Guillows Lancer.

Bob

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 3rd, 2014 at 9:27am
Thanks Bob!  I'm still "new" at magnabuilding, so I still have a lot to learn.  Getting decent magnets here (!) is not that easy.  Seems that ferrite jobbies are no longer high-tech enough for the Euro locale.  I have to order the rectangular mags with the hole in the middle out of the States... the rest out of England.

I also still use/prefer a "standard" building board (MDF base with cork topping) for the majority of my FF builds.

If you have some FUTURE (or whatever they changed the name to), give the canopy a coat on the inside and out.  It might clear up the fogginess.  Canopy Glue of Aileen's Tacky will still glue it.

Title: Re: Any Twin Cookup
Post by Don McLellan on Aug 4th, 2014 at 10:21pm
Hi Peter,

When I built my Rutango, I found the sheet balsa rudders to be a little heavy; I had to add nose weight to get to the calculated c of g.  I think you are doing the right thing making lighter, stick rudders.

Don

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 5th, 2014 at 1:44pm
Fins separated and both canard halves built with the left one cambered.  Started gluing the nacelles together and I'll be leaving them as Bill designed (square... maybe ::)) rather than adding a bit of roundness to the top.

Don, did you log any of your component weights?
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Title: Re: Any Twin Cookup
Post by Tom Akery on Aug 5th, 2014 at 5:17pm
staubkorb...components looks great so far.  This is a really intriguing model.  I look forward to each step of the construction and especially to how you get her to fly.  I've got a canard (Starship) I've got to finish when I dig it out of the boxes from moving. 

Very nice craftsmanship! [smiley=thumbsup.gif]
Tom

Title: Re: Any Twin Cookup
Post by Don McLellan on Aug 5th, 2014 at 7:59pm
Hi Peter,

I built my Rutango for the Quick Build Challenge on SFA so didn't really have time to weigh anything.  Also, my scale weighs to the nearest gram, so .5 gram looks exactly like 1.4 grms on my scale (ie 1 gram).

I can tell you that I just weighed it and the all up weight with rubber, props and a little nose weight is 32 grms.  Quite porky for a peanut!!

Title: Re: Any Twin Cookup
Post by Tom Akery on Aug 5th, 2014 at 9:02pm
Hi Y'all,

Got the Pfeil (Arrow) painted today.  It was a new technique for me today.  I used craft acrylic paints.  Took a few tries on the foam board before I got the mixture right to spray correctly.  Just like learning how to airbrush all over again.  Been a while since I used the airbrush.  After I got the mixture right it was fun to paint.  I also learned to use the Krylon after the acrylic not before.  Tends to cause the water based paint to bead up instead of lay down and cover.  I'm going to use this  again.

Here's some pics of the painted plane.  Need to do the panel lines and markings next.

Tom
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Title: Re: Any Twin Cookup
Post by cdwebb on Aug 5th, 2014 at 9:38pm
Tom, what an eye catcher! Nice work with the airbrush. I know you've had this vision in your head for a while, but for me, at least, it was hard to envision the final product. Beautiful work that is really coming together!

I'm always amazed at what some color will do. It absolutely makes it come to life!!  [smiley=thumbsup.gif]

Title: Re: Any Twin Cookup
Post by Don McLellan on Aug 5th, 2014 at 10:23pm
Hi Tom,

Exceptionally nice work!!  Another beautiful model.

Don

Title: Re: Any Twin Cookup
Post by Tom Akery on Aug 5th, 2014 at 11:15pm
Thanks CD and Don for the kind comments.  I'm starting to like it and visualize it flying over head.

Tom

Title: Re: Any Twin Cookup
Post by bigrip74 on Aug 6th, 2014 at 7:09am
Tom: I take It that you used an airbrush on the camo and everyone else has already stated it is a really nice job  [smiley=thumbsup.gif]

Bob

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 6th, 2014 at 8:20am
Tom,
your "anteater" is really looking sharp" (anteater-ameisenbaer was another nick for the aircraft).  After I get my RUTANGO and D.VII done, I may have to dig the West Wings kit of the Do off the shelf!

Don,
The main wing area of the "full size" RUTANGO is 120 squares.  Peanut size works out to about 43 square inches, so the wing loading is a bit high.  Add a bit of span the the "duck" (maybe an inch) plus another degree of incidence

Title: Re: Any Twin Cookup
Post by Tom Akery on Aug 6th, 2014 at 9:21pm
Do 335 update...
The paint dried nicely and it was time for panel lines.  So spent the afternoon drawing panel lines on the top and bottom and sides of the plane.  I used a white gel pen for the bottom and it turned out ok but I'm not really thrilled with this pen.  I'm going to look for something better.

Here's the pics...
Tom
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Title: Re: Any Twin Cookup
Post by Tom Akery on Aug 7th, 2014 at 6:40pm
finished the marking today and added the exhaust flame dampeners and guns on the nose. Ooops bumped the radar antennae on left wing.  Here's the pictures...
Tom
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Title: Re: Any Twin Cookup
Post by mitch j on Aug 8th, 2014 at 6:43am
Wow Tom, thats turned out fantastic mate!! Between internet problems & just being too busy I haven't been keeping up with whats going on. My own building has come to a bit of a standstill too....Another fantastic build!!

Title: Re: Any Twin Cookup
Post by bigrip74 on Aug 10th, 2014 at 9:10pm
Tom: you have outdone yourself with this airplane. Cannot wait for those inflight photos.

Bob

Title: Re: Any Twin Cookup
Post by Tom Akery on Aug 10th, 2014 at 10:01pm
Well the only thing left to do is make the props. Not having a pusher prop of 10 inches I decided to make the MIL (Minimum Induced Loss) prop blades. Click Here  I laminated the blades from 1/16" sheet balsa using the "MIL" pattern using a 5" pattern. Edit 10/15/2014: Should have used 1/32 or 1/20 for the laminations Using the formula for the diameter of the bottle I arrived at 19 degrees.   You notice on the soda bottle, filled with water to keep it firm, I drew four vertical lines and using a protractor I marked off 19 degrees on each side of the vertical lines.  For the tractor blades they are tilted in line with the line on the left side of the vertical.  For the pusher prop tilted to the right!  don't forget to mark these blades when you remove them from the bottle  I then used white glue to laminate the blades.  I didn't wet the balsa there's enough moisture in the glue to aid in the bending of the balsa.  I brushed glue on the surface of both laminations that would meet together.  Be careful with this also, easy to put glue on the wrong side of one of the sheet blades to be laminated.  Once glued I place the blades on the bottle and aligned the blades with the proper angled lines and taped them to the bottle using masking tape. Top, Middle & Bottom of the blade.  Then moved on to the next blade.  Adding more tape as each lamination is added.  Once all the blades are mounted on the bottle, I taped all the balsa down so there wouldn't be and edges left away from the bottle's surface.  I then left it to set for 24 hours to cure.

Once cured, I sanded the edges sharpening them down to the glue and tapering them towards the middle of the blade(using the center line drawn from the pattern). 

Here's a few pictures showing my progress.

With these blades I can vary the pitch as I trim the bird for flight.  I'll be using the front(tractor) prop for initial trimming.  Then add the rear(pusher) prop later.

Additional modification:  I have also noticed that if you want a counter rotating prop as a pusher the leading edge of the blade needs to be below the angled line on the right side of the vertical on the bottle.  So I'm laminating up another set of blades for counter clockwise rotation (CCW).

Tom
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Title: Re: Any Twin Cookup
Post by Don McLellan on Aug 11th, 2014 at 12:41pm
Exceptionally nice 335 Tom.  Great detail work. 

I've used that style of blade before, and they seem to work for me.

I didn't build my Rutango for this CU, but am trying to get it to fly.  This very short flight is typical of what's happened so far.  I just can't get the nose to point a little up rather than down under power:  https://www.youtube.com/watch?v=TUBAIgqjj5E

I've tried trim tabs, gurney strips, moved the c of g a little etc but nothing has worked. 

So I've built a slightly larger span, lifting canard to see if it will hold the nose up a little better.
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Title: Re: Any Twin Cookup
Post by Tom Akery on Aug 11th, 2014 at 3:06pm
Don,
What a great looking plane.  Just weird enough for me! ;D :D ;) My kind of airplane! 
Does the name have any specific meaning/symbolism?

Looks like it wants to fly in the short video.  Was the downward path at the end due to the things you have mentioned, or was the winds ending?  Looked pretty good at launch and mid way through. To me.  I'm really interested in your trimming of this one.  I've got to finish my Starship and the canard setup is very similar.  Except the Starship is a pusher.

Tom

Title: Re: Any Twin Cookup
Post by Don McLellan on Aug 11th, 2014 at 3:23pm
Hi Tom,

I believe Bill's design was influenced by Burt Rutan's airplanes, so suspect that is how the name came about.

With all my test flights, the model flew into the ground; there were still lots of winds remaining.  As mentioned, I've tried trim tabs on the main wing and the canard, a gurney flap on the canard, changing the angle of the canard, moving the c of g reward/forward, all resulting in 'non-flights'.

Hopefully a larger, lifting canard will make for a slightly longer, more predictable flight.

Title: Re: Any Twin Cookup
Post by bigrip74 on Aug 11th, 2014 at 8:41pm
Don: nice build so far. Where is the CG on this airplane?

Bob

Title: Re: Any Twin Cookup
Post by Don McLellan on Aug 11th, 2014 at 10:28pm
Hi Bob,

I calculated the c of g to be just aft of the LE at the root of the wing: maybe 1/2" to 3/4" aft of the LE. 

As I mentioned to Peter (off line) I've misplaced the calculation (mostly because I was struggling to get this to fly and probably chucked it), but it was from an on-line calculator and I 'suspect' correct. 

Don
RuTango_14.jpg (110 KB | )

Title: Re: Any Twin Cookup
Post by Tom Akery on Aug 11th, 2014 at 10:39pm
Don...
This "rutango" is just outstanding.  I love this design and it's definitely moving up on my "To Do" list!  Please keep us informed on your trimming progress and make it easy for those of us who follow after you!!! [smiley=thumbsup.gif]

I won't be able to match your printed tissue, amazing by the way!, but we'll get something done.  I may just start one right away, as the Do335 is almost done!

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 12th, 2014 at 9:58am
Keep at it Don!  It looks like it is trying to fly.

Have you had a chance to try it with the new canard?  If you can get the thing gliding, it should do ok.  I'm still fairly convinced that the positive incidence of the main wing has something to do with the problem.  I'm going to try to make my main wing adjustable till the glide gets sorted, but the nacelles will pose the main problem as reducing the incidence at the center will droop them.  Adding incidence to the canard beyond a certain amount will make the whole plane look weird.

Attached are two shots of my canard "test bed".  There is no main wing incidence other than a bit of Phillips Entry (the wing does have an "airfoil" of sorts) - maybe an effective 0.5° with the canard set at about 4°.  CG is the black marking above the wing, and it glides VERY well.
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Title: Re: Any Twin Cookup
Post by staubkorb on Aug 12th, 2014 at 10:17am
I've gotten the wing outer panels built and will be starting the center section.  As previously stated, I'll be reducing the incidence from what is shown on the plan to about 1° (as opposed to the 3°).

Studying the plan a bit more, I might be able to accomplish the mod without having to do too much glue/re-gluing.  The fuselage sits within the forked LE of the center section, so I can use the cross-piece as a pivot.  The nacelles will still be a problem...

Have to think this thru...

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 14th, 2014 at 3:27pm
Main wing center section is finished except for sanding and forming the LE.  I'm now picking out the wood for the fuselage.  I can use lighter than "normal" wood for the main longerons since there is no tensioned rubber band to worry about.

I got "remembered" as to why I've only built ONE modern multi-engined aircraft (Comet A-26 INVADER) - one has to build (in these cases) THREE "fuselages" (I HATE building fuselages :P ;)) - tho there are LOADS of multis that I'd like to do.

Title: Re: Any Twin Cookup
Post by Tom Akery on Aug 14th, 2014 at 4:47pm
Sounds good Pete...how bout some pictures?

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 15th, 2014 at 6:57am
Your wish is my command ;) ;D!

As of last nite...
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Title: Re: Any Twin Cookup
Post by Tom Akery on Aug 15th, 2014 at 9:27am
Great looking set of bones so far. [smiley=thumbsup.gif]  This model just keeps gnawing at my thought processes.  Guess I'll have to move it up on the "To Do" list.

Tom

Title: Re: Any Twin Cookup
Post by bigrip74 on Aug 15th, 2014 at 7:57pm
Nice sub components, and they look so clean.

Bob

Title: Re: Any Twin Cookup
Post by Don McLellan on Aug 16th, 2014 at 12:16am
Very, very nice Pete.  Now just the fuse to build.

Don

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 16th, 2014 at 7:27am
Thanks guys!  The  camera hides a lot ;).

I've been playing with my canard chuck gliders to try and get a definite idea of the best compromise between the "power on" and glide speeds.

Canards have a very narrow "no trim change" bucket where they will climb under power and still have a decent glide and is even MORE apparent with this configuration due to the fully loaded "stabilizer".  Trimmed for a nice glide, they'll climb like gangbusters, or even loop, under power if the speed differential is too high.  Downthrust SHOULD take care of this tendency, but will probably need more than what might be considered "normal" so more care must be taken with the prop/rubber selection.

What I'll be looking for is a steady, relatively shallow climbout and a (hopefully) flat glide.

One side of the fuselage is framed.  I used 2mm square wood (0.3mm shy of 3/32nd inch) with a density of about 7.5# cut from a sheet of "B" grain.  Springiness was equal in both planes.  I would have preferred true "A" grain, but none to hand.  I've added a few small gussets to give a bit more gluing strength to the joints.

This being a BETA build, I'm NOT going to attempt any fancy covering other than the name and a reference to Bill.  I want to get the design finalized first with a possible full sized build to follow.

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 18th, 2014 at 6:15pm
Both sides are framed up but still have to add a gusset or three, then separate the units from each other.  I built the sides directly atop one another and was AGAIN painfully reminded how much I miss Sig and Midwest balsa with their accurate thicknesses.

Hope to add the x-members tomorrow.

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 21st, 2014 at 7:50am
Main fuselage is framed up with the exception of the rear turtledeck/wing fairing.  It didn't come out quite as square as I'd hoped but is still OK (lousy wood thickness tolerances and a Master Airscrew/KAVAN stripper that is nearing its end).  Stuck the bits together to get an idea of the proportions - it's big (comparatively speaking)!  The "full sized" one at 21.5" would be a serious storage problem for me unless I made it with a removable main wing (considering it for THIS one).

A detachable wing would work fairly easily with this design using a tongue-in-groove/magnet setup, tho the fins would be susceptible to damage.  The underfin would need to be "solid" unless I go with the landing gear (looks nice also).  I will be building in the gear hardpoints.

DSCF6079_FuseSide_rutango.jpg (159 KB | )
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DSCF6083_AddingXmembers.jpg (81 KB | )
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Title: Re: Any Twin Cookup
Post by Tom Akery on Aug 21st, 2014 at 10:34am
Looking good. I'm interested in your removable wing set up.  Please include pictures of this if you go this route.  This is really an intriguing model.  Guess I'll have to print up the plans and strip some wood. 
Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 21st, 2014 at 1:07pm
It definitively is an intriguing plan-form!  If you do decide to cut wood on one give me a shout beforehand - there are a couple of drawing errors that can really spoil your day and you might want to hold off long enough for me to get some flight testing done to get the setup into the ballpark.

I haven't been really paying too much attention to weight, so I threw the bones on the scale...

:o :-? :)

14.1 grams, with a LOT of wood to come off (leading edges, nose block + general sanding).  Still to build: front and rear turtle decks, nacelle plugs, landing gear, props.

I'm aiming for an AUW (minus rubber) of <30 grams, but it should still be OK up to about 35-38.

Time will tell ;)

Title: Re: Any Twin Cookup
Post by Colonel Manfred von Holstein on Aug 21st, 2014 at 3:20pm

staubkorb wrote on Aug 18th, 2014 at 6:15pm:
Both sides are framed up but still have to add a gusset or three, then separate the units from each other.  I built the sides directly atop one another and was AGAIN painfully reminded how much I miss Sig and Midwest balsa with their accurate thicknesses.

Hope to add the x-members tomorrow.


After coming to the realization that the majority of wood that I have been using was overweight I went out with a scale to buy some new stock.   SIG wood was by far the best available strength for weight that I found locally.  Is it not available anymore or just not available in Germany?

ps I don't believe that nonsense about the kindness of your camera. She's a real beauty!

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 23rd, 2014 at 4:59pm
Danke Oberst!

My magnets helped enormously.  They are perfectly rectangular with plan edges which keeps everything square.  I just have to learn to let the glue dry completely before removing them ::).

I'm almost at the covering stage, having shaped the leading edges of the main wing (still have a bit to do on the right tip TE) and the nose turtle deck.  The sanding removed almost a full gram, and the "new" bits have only added 0.2 grams so I'm under 14gm for the bones.

I'm going to throw a profile "fuselage" together to test my idea about the main wing incidence before risking the built-up fuselage - once I get the wings covered.  Essentially it'll consist of a few 1/4" sticks to get the flight surfaces in a similar relationship to each other.

Now I have to decide just how far to go with the decorations (printed tissue).

Title: Re: Any Twin Cookup
Post by Don McLellan on Aug 24th, 2014 at 1:14pm
Hi Peter,

Beautiful work!!

One thing I would suggest is to open up the slot at the front so you can make some trim adjustment to the canard if required.  (Just a thought).

Don

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 24th, 2014 at 4:12pm
Hey Don,
I already thought about that, and decided to make the main wing "adjustable".  I DID, however, make the canard carry-through out of 1/16th sheet so I can adjust it as well - if needed.

Title: Re: Any Twin Cookup
Post by Don McLellan on Aug 25th, 2014 at 11:58am
Hi Peter,

Grey moment for me:  I remember you mentioning that you're making the wing adjustable.

I finished covering my new, larger, lifting canard last night, so hope to give my Rutango a toss in the next couple of days and will report back.
RuTango_15.jpg (101 KB | )

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 25th, 2014 at 3:40pm
Looking good Don!  How much were you able to modify the incidence?

I spent a few hours going over the plan, measuring angles (Thank you Adobe XI) using the  base datum = fuselage position on the plan - not gear set.  The canard is at +5° and the wing sits the fuselage at +2.3° plus 1° effective incidence (chord line) - so there is only ~2 decalage!  WAY too little, as these birds need a bit MORE than what is considered "normal" (3°).

Raising the TE of the main wing 1/4 inch (on the full sized model, pivoting at the "fork former") drops the incidence to about 1° - airfoil bottom parallel to the datum.  For my model, this translates to raising the TE about 5/32nds, which is where I'm going to start.

Title: Re: Any Twin Cookup
Post by Don McLellan on Aug 25th, 2014 at 8:33pm
Hi Peter,

Those are almost exactly the same angles I came up with (from the drawing).

I didn't change the angle of the canard; just shoved it in the slot with a light dab of glue.  I did give it a couple of glide tosses this afternoon and found that I still needed trim tabs on the canard to get a slightly reasonable glide.  I think I'll give it a powered toss with the tabs in the next day or so.  Have to say it did glide much better once the tabs were added.

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 26th, 2014 at 7:26am
Don, before you do another powered flight try moving the CG BACK a smidge- maybe a 1/16th at a time.  I know it sounds counter-productive, but it just might help.  The decalage is highly dependent on the speed that the plane does the most of its flying and in your case, with "short" decalage, it's gonna need a higher speed to get the canard working - or a slightly rearward CG to slow things down.

The CG calc program for canards is, to me, a bit conservative.  I ran my "SHARK" thru it and it spat out a CG that doesn't work at all - unless I cranked the canard up to almost 8°.  Then again, I had to guesstimate the areas and take the moments off the model itself as the CAD files are in TCW (TurboCad propriety) format on my old confuser and I haven't tried to run a copy on DraftSight yet.

I've gotten my ersatz fuselage done and as soon as I get the flying surfaces covered (maybe today), they'll get rubber banded on for some tests.
DSCF6086.jpg (54 KB | )
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Title: Re: Any Twin Cookup
Post by Tom Akery on Aug 27th, 2014 at 11:45am
enjoying this dialogue fellas...following with great interest.
Tom

Title: Re: Any Twin Cookup
Post by Don McLellan on Aug 27th, 2014 at 11:36pm
Hi Pete,

Well, I think I'm still at square one with trying to trim:

http://youtu.be/UBvqhtHjgUU

I did not try adjusting the c of g, or altering the trim tabs; still a pancake special.  I'm beginning to suspect that the acceptable trim limits are quite small for what I have built, and I'm still somewhere 'out there'.

But have to say I am enjoying your build and am following with great interest:  please show me the way!

Don

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 28th, 2014 at 6:46am
I think you're close!

One:  it is windy and the buggar was flying till it started flying with the wind.
Two:  once the airspeed dropped, it did a typical "canard" mush.

The second launch might have been a bit too brisk and at a too high AoA.  The wind, and combined brisk toss/high AoA pitched the nose up creating a stall and resulting "mush".  It wasn't high enough to start flying again.

A tiny bit of nose weight might help.

Have to ask - how does it glide now - protected from wind influence?   Also, are you carrying any downthrust (I don't think it needs any at all) - other than what Bill drew into the plan (3°).  The props are only a miniscule distance forward of the balance point, so are not really contributing anything other than weight, and are also very close to the CG which usually negate any large thrust offsets.

How do you stooge the thing?!?

I've covered the canard and done the fine sanding on the wing center section on mine so far.  Have to do some sanding on the nacelles and attach the 1/64th ply prop block reinforcement and the peg hardpoints.

I want to be able to give the wing a test toss by the weekend...

Title: Re: Any Twin Cookup
Post by Don McLellan on Aug 28th, 2014 at 11:42am
Hi Pete,

My videographer (wife) is my stooge. 

After I put the trim tabs on the canard the glide was fine.  Prior it was a lawn dart.  And just for the record I made a last flight (not for public display) without the trim tabs, and it became a big time lawn dart, again.

Down thrust is approx 3 deg as per the drawing.  After looking at the video again and again and again....... I think I may reduce this to close to zero.

Looking forward to more progress on you Rutango.

Don

Title: Re: Any Twin Cookup
Post by Tom Akery on Aug 28th, 2014 at 5:05pm
Keep it up Gents....I'm looking forward to your solutions and my possible up coming build.  That is just an outstanding looking airplane...

I think you've almost got it solved Don! [smiley=thumbsup.gif]
Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Aug 29th, 2014 at 10:12am
I ran another CG calculator that allows oddball wing planforms, first with the "standard" setup (non-cranked wing) giving me the CG @ 0.25" behind the root LE - on my sized model.  The "cranked wing" calc worked out to 11/16ths" from the root LE.  I used a 10% static margin (right in the middle of the accepted limits).  Changing to an 8% static margin moves the CG back about 3/32nds"

Covering the center section now with white tissue.  The tips will probably get done in red.
CG-Calc1.jpg (195 KB | )
CG-Calc2.jpg (190 KB | )

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 3rd, 2014 at 3:14am
Covering underway - canard, main wing center section and the nacelles done but not yet shri-shra-shrunk (skunk?).  Prop plugs need to be drilled and shaped.  A bit of printed tissue for the nacelles and whatever other markings will be tissue-cals.
DSCF6089.jpg (97 KB | )

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 3rd, 2014 at 10:08am
The tips for the tip panels are getting the Hoerner treatment (Anti-Vortex attachments).  Ce$$na turned the tips downwards, other users turned then upwards - both ways work, but these gizmos were one of the forerunners to the tiplets now predominant on most airliners.  Turned upwards one gets an added benefit of increased effective span, and the natural curvature of the upper or "inside" surface of the tiplet forms almost the perfect airfoil to the attachment (if shaped properly ::)).  The turned down variant kills a lot of tip spill (and the resulting vortices), but I don't remember what other benefit they provide - other than being easier to fabricate.

Mine are basically carved from a length of 6mm square balsa (tiny for my mitts) and were a PITA to do.

Photos show the "before" and "after".  Still a bit of fine sanding to do before covering the tips, and I'm gonna give the model a registration!  Haven't decided whethe it will be a German (D) or Brit (G), but the peelot is gonna be Bill Brown if I can find a decent 3/4 profile photo of him.
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Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 3rd, 2014 at 10:39am
Looking Good Pete.  The tips are outstanding.  Gives me some ideas for a few models on the "To Do" list.  This is a very intriguing build.  Thanks for all the info and keep it coming.
Tom

Title: Re: Any Twin Cookup
Post by bigrip74 on Sep 3rd, 2014 at 8:51pm
You guys are killing me with these beautiful airplanes, NICE JOB PETE especially on those tips. [smiley=thumbsup.gif]

Bob

Title: Re: Any Twin Cookup
Post by Don McLellan on Sep 4th, 2014 at 10:32am
Very nice Pete!  I like the wing tips; great idea.

Don

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 4th, 2014 at 3:30pm
Ok fellas,  I've finished the Dauntless and am ready to start the Rutango!  I've printed up the plans and started cutting out the rib patterns for the wing. 

Don...you made a new lifting stab for your Rutango...some details please?  Wood size, ribs construction, increased span?

Pete...you mentioned some drawing errors...please enlighten me re: those. 

I'm looking forward to this build...
Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 4th, 2014 at 6:23pm
Are you going to build it full size?  If so, take the wood sizes directly from the plan (3/32nd for the main body) but watch out for the wing center-panel LE's - they taper from the root to the nacelles in height and the lines should be parallel in the plan view (they are not equally spaced and are bit different on each side).  The LE of the tip panels is DOUBLE tapered.  Use SOFT balsa for the main wing LE's  The spar notches on the right tip panel are too far to the rear and don't match the cutouts in the ribs.  Ribs/spars can be 1/16th, but 3/32nd might be better for the spars (main wing).  The sheet nacelle sides show as ~1/16th - if you have good stiff wood it should be ok as it is P-30 size.  Add gussets wherever you feel they might be needed, but try to keep the wing/nacelle unit as light as possible.  You may have noticed that I had to build up the TE area of the wing ribs - even at 75% they were too thin.  Bill apparently meant to use 1/16th for the trailing edges,but I think 3/32nd would be best.

Build up the fin/rudder assemblies (1/16th) unless you have some GOOD light but stiff "C" grain, but leave the sheet sub fin as-is - it prolly gets a bunch of abuse.  Build up the canard the way I did using the spar location as the high point and fudge a FLAT bottomed airfoil (I use a HLG glider style 'foil) and make it the height of the cutout in the fuselage, but don't forget the tissue thickness or you won't be able to slide the completed canard thru (or just make the slot a bit wider).

AGAIN, IF FULL SIZE: The canard MAY be fine as drawn - it's working in a better Reynolds area than those of the 13" (Don's) version.  Mine is also "stock".  I'll let you know if it works.

Draw a reference datum on your side view thru the nose center point using the edge of the printout as the base reference so that you can measure angles - if necessary - but hold off on the main body construction till I get some initial incidence data with my ersatz fuselage.  Should have some by late Saturday.

Make sure that all assemblies are as close to perfectly cut and as square as possible!  Everything on this model depends on accuracy.

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 4th, 2014 at 6:35pm
Thanks Pete...
I am going to build full size.  I just printed out the plan in tiles and taped them together.  I noticed the differences in the leading edge.  I'll wait on the fuselage till you get some more data completed.  I think that I'll build the canard per plans as suggested and follow your construction.  Thanks again. 

I was looking on SFA at pics of "tonight at escadrille HARFANG" and there appears to be a rutango in flight in one of the last photo's of reply #4027 Click Here

On second examination it's not a rutango but the British prototype Miles M.39 Libellula.

Make sure that all assemblies are as close to perfectly cut and as square as possible!  Everything on this model depends on accuracy.

No pressure on this build. LOL :o :D ;)

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 4th, 2014 at 6:50pm
;D That's the (model of) Scaled Composites "Voyager" (Rutan designed) round-the-World record holder (Burt Rutan and Jeanna Yeager at the controls).  I don't think I'd want to try that as a model ;).

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 4th, 2014 at 7:00pm
I went back and edited my post as you'll see.  I wouldn't try the voyager either.  But it sure looks good in flight.  Those guys are amazing!  Wish I had a club close by for the camaraderie.  But S&T will have to suffice! It does pretty good!!! [smiley=thumbsup.gif]

I think Bill plan bashed the Miles M39 Libelulla.  See the picture.  He use the twin vertical stabs on the wing instead of on the tips and swept them for a more modern look. But the layout is very similar.
Tom
300px-Miles_M_39b.jpg (13 KB | )

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 4th, 2014 at 7:11pm
HAH!  I didn't scroll down far enough...  You'll notice the high aspect ratio of the canard on the Libe - that is what is more important in canard design rather than simply "more area".  Tacking on more span is an easy mod if the plane doesn't want to play fairly.

The Miles is also on my primary build list...and here is a profile "scale" model tha can be built as a glider or rubber powered (single motor).
https://www.stickandtissue.com/cgi-bin/yabb2/YaBB.pl?action=downloadfile;file=Miles_M35_Libellula__plan_1960.pdf (282 KB | )

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 6th, 2014 at 8:22pm
Got the canard constructed after doing some household chores....pictures coming later.  Found this quote:
All modern aircraft have four dimensions: span, length, height and politics.   TSR.2 got the first three right - Sir Sydney Camm

How true...also true of the Northrup YB49...
Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 7th, 2014 at 12:35am
Had similar "issues" yesterday also, Tom.  House meeting in the AM and away the rest of the day.  REALLY ticked me off as it was a totally beautiful and nearly windless day - ALL day!  Would have preferred to go flying :(.

Anyhoo, all flying surfaces covered and the prelim shrink done.  Gonna try to get a coat of banana oil on so I can give the setup a toss in the PM (after the Formula 1 race ;)).  I glued everything together before shrinking and no warps developed (light steam shrink method).  The nacelles, resting flat on the board, were attached with the LE of the wing panels shimmed up 1/16".  This will give a bit of incidence, but I believe that the nearly 5° in the canard might be a titch too much, so it may work out in the long run.  Still trying to decide whether to carve a couple of props (contra rotating) or do what Don dood - 'course, I could yogurt a few... ::)

Don mentioned that his was gliding reasonably well with the tabs he had attached.  I'm almost convinced that all he needs is to take out most of the downthrust - the plane is powering into the ground.

DSCF6098.jpg (91 KB | )

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 7th, 2014 at 10:38am
Race is over ::), 75% Rutango has taken air [smiley=2vrolijk_08.gif] on the stick "fuselage" [smiley=thumbsup.gif].  WITHOUT fins! :o!

OK, these were only test tosses in the backyard, but were more than promising.  Without fins, there was a noticeable lack of directional stability, but does display the float that I'm after [smiley=thumbsup.gif].  I discovered that my "stick" is about a quarter inch longer than the real fuselage, moving the main wing back by that amount.  This changed the calculated CG (measured as a value from th canard LE) causing a dive.  After compensating for the error, the rest of the tosses were fine.

I got all of the test glides on video, which will be posted as soon as I get them loaded into the confuser.

The CG?  So far, right on the front spar location of the main panel.

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 7th, 2014 at 3:00pm
http://youtu.be/wWnKh951O4s

Title: Re: Any Twin Cookup
Post by bigrip74 on Sep 7th, 2014 at 10:09pm
Pete, nice video of your Rutango's toss. Cant wait to see the powered photos.

bob

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 7th, 2014 at 11:16pm
Outstanding work Pete...I'll progress on my construction of the main wing and wait to see what your fuselage is going to do.  I'll also re-read the posts to make sure I'm getting everything!  Congratulations again on the test glides... [smiley=thumbsup.gif] [smiley=2vrolijk_08.gif] [smiley=vrolijk_1.gif]
Tom

Title: Re: Any Twin Cookup
Post by Don McLellan on Sep 9th, 2014 at 1:17am
Hi Peter,

Very nice glide!  I think your Rutango will be an exceptionally well behaved flyer.

Don

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 9th, 2014 at 6:34am
Thanks guys!  The glides were a bit "tense" since I was sharing my "field" with the house 5 year old (he quickly destroyed the EPP glider I gave to him earlier this "summer") and a few of the other denizens ;).

I almost created extra work by wanting to use small Peck bushings, but found that I had no more 1/32" wire.  Metric stuff won't fit - 0.8mm is just a tad too thick and the next available size smaller (0.06mm) has way too much slop - so I'll have to fabricate bearings from brass tubing or tin/alu plate.  I'll give the first powered tests on the stick fuselage.

Running into another BIG supply problem.  I got my last tin of banana oil from SAM's and the bottom is getting very close to the top - not sure if I have enough to seal the complete plane.  The problem stems from the fact that my tin was sent "erroneously" - they refuse to accept my re-order.  I THINK that Flighthook carries it, but I somehow lost the pdf I had of their stock with my confuser upgrade, and the website is still not quite there.  I'd LOVE to make a trip to England, but not just to pick up some dope (the painting stuff - for the snoopers ;) :P).  The new mailing restrictions (and costs!) are getting to be a real pain in the arse >:(.

Don, have you tried another flight with reduced downthrust (with tabs)?

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 9th, 2014 at 9:33am
Happy correction to the last msg.  A couple of nice lengths of 1/32nd wire were found in one of my old kit boxes (rc).  I forgot (almost) that after coming to Germany, that I "converted" most of my Imperial/SAE fixings to metric.  I will, however, need to order some 0.032 ID brass tubing for prop bushes - not needed just now.

Title: Re: Any Twin Cookup
Post by Don McLellan on Sep 9th, 2014 at 7:51pm
Hi Peter,

No haven't re-tried my Rutango, but think I have convinced my 'stooge' to go flying tomorrow.  I've taken most of the down thrust out of the props, and reduced the size of the canard trim tabs. 

The glide looks somewhat promising, but I've been down that road the odd time before.................

Will report back.

Don

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 9th, 2014 at 11:34pm
Don...when you say tabs, what exactly are you referring to?  Are they gurney flap/strips or something else? Any pics?... I'm anxiously  awaiting news on your next test flights! [smiley=thumbsup.gif]

I've completed the wing construction.  I still have to do some finish sanding.  Tomorrow I'll work on the nacelles. 

Pete...have you nailed down the incidence completely yet?  I'm liking the glide tests!

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 10th, 2014 at 5:21am
Tom, I'm pretty confident that it's "in the realm" and will add a spacer to the built-up fuselage to match.  I'm going to be out most of today, but when I get back (if early enough ;)) I'll work out the measurement for the full-sized model.

Differences in tolerances (measuring/cutting/fit) will still require individual fine tuning, but one thing to keep in mind is to make sure that you leave enough clearance (fuselage width) for the center panel LE fork to just slip over the fuselage when both are covered.

Don, good luck with the next test and treat your "stooge" well ;).

I'm still up in the air about whether to use opposite rotating props or not :-/...  Blanks have been laid out for laminations (not fan style).

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 10th, 2014 at 10:23am
Making some progress on the wing now.  Canard finished and dihedral added as per plan 3/4 inch at each tip.  Got the outer wing panels done and sanded and just completed the central wing panel.  Here's the bones pics...
Tom
rutango_wing_and_canard1.jpg (121 KB | )
rutango_wing_and_canard2.jpg (180 KB | )

Title: Re: Any Twin Cookup
Post by Don McLellan on Sep 10th, 2014 at 12:13pm
You don't fool around do you Tom??  Great progress!!

Will you add wing tips similar to Pete's Rutango?

Don

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 10th, 2014 at 2:10pm
Don...yes, I'm hoping to duplicate Pete's wingtips as well.  Still looking at the nacelles and fuselage. I've got some pretty stiff 1/16 that I think will work well there. 

Any luck with the next series of test flights Don?

Hope to complete the nacelles today and then start on the fuselage.

Tom

Title: Re: Any Twin Cookup
Post by Don McLellan on Sep 10th, 2014 at 4:25pm
Well, had the Rutango out again this afternoon and it once again 'lawn darted'.

The only 'flight' broke the front former on the port nacelle.
RuTango_16.jpg (92 KB | )

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 10th, 2014 at 6:50pm
Bummer Don!!!!

Looks like a fairly easy repair, especially for someone of your craftsmanship level!  Hope you get her back in the air soon.

The canard on your Rutango is that the stock/as per plan incidence?  I guess the blue showing at the trailing edge is the tab?

Hope you can get her sorted out and no more lawn darts!
Tom

Title: Re: Any Twin Cookup
Post by Don McLellan on Sep 10th, 2014 at 7:18pm
Hi Tom,

Yes, it is close to the incidence as per the plan.  I did, however, make the span of the canard about 130% larger compared to the plan.  And the trim tabs made are made from blue painter's tape.

Don

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 10th, 2014 at 7:25pm
Thanks Don...
Looks like Pete's stick mockup uses a bit more incidence on the canard.  I'm also thinking of using my tips to curve down instead of up!

Don't know for sure what that will do as opposed to Pete's curved up but thought I'd give it a try.

Tom

Title: Re: Any Twin Cookup
Post by Don McLellan on Sep 10th, 2014 at 11:18pm
Hi Tom,

Also I think Pete has the wing at 0 deg (or so).  The plan is something like 3 deg up at the LE.

My wing is up 3 deg at the LE, and I think that is a problem.

Don

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 11th, 2014 at 12:06am
I'm going to wait on the fuselage construction till I get some insight as to the canard incidence and the decalage for both wings! 

Got one nacelle constructed and used the machine squares to keep the nacelles square!  I'll need to set the incidence on the sides of the nacelle to make sure that the wing is consistent on each side of the nacelle.

Here's the pics of one nacelle...
Tom
Nacelle_build_1.jpg (151 KB | )

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 11th, 2014 at 1:29pm
Don is correct about the main wing incidence.  I used the bottom edge of the paper from the print-out as the datum, moving it up to intersect the top longeron where the forward "fork" former sits.  The canard is set up as shown on the plan.  For strength, make that former solid

You can either run the top longerons straight back, as per plan, and simply add a spacer or splice in a new flat one, adjusting the uprights (would result in a stronger wing mount, but would make adjustments more difficult).

Attaching the wing panels to the nacelles:  I raised the LE's about 1/16" at the bottom of the airfoil (where the rib meets the LE).  This results in a tiny bit of downthrust and probably isn't needed, but it prevents the nacelles from appearing to point "up".  I also "built in" the dihedral in the tip panels by blocking the tip rib up before gluing the nacelle rib - using a square to keep the nacelle rib vertical.

Cover (grain chordwise) before assembly using white glue wherever the tissue might creep, but DO NOT shrink.  Shrink AFTER the panels are attached to the nacelles - helps keep everything straight.

I've just glued up my prop blocks (5") - THREE of them-  I'll make one "backwards" for opposite rotation but will have a spare "normal" one in case the contra setup doesn't work.  Getting them from block to blank is the only part of prop carving that I hate - especially in sizes under 8".  It's too easy to screw up the cut.

Don:  Don't gie up!  Add a Gurney flap (1/16 sq by about 1.5 inches long) to the upper TE of the outside wing panels (might have to adjust the CG).

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 11th, 2014 at 8:43pm
Made some more progress on the Rutango...
Got the wingtip panels done with a kinda "Robertson's STOL wing tip" set up. 

Here's the mockup and pictures of the wingtip details.
Tom
Mockup_of_nacelles_and_wings2.jpg (170 KB | )
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Title: Re: Any Twin Cookup
Post by Don McLellan on Sep 11th, 2014 at 11:32pm
Your Rutango is progressing by leaps and bounds Tom.  I do like the wing tips!

For my Rutango Peter, adding tabs to the canard had the biggest influence:  on the glide that is. 

I tried gurney flaps on both the canard and the wing tips, and as mentioned, the canard flaps had the biggest influence.

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 12th, 2014 at 6:36am
Ce$$na spamcan style tips!  They should work fine.  I also see that you added diagonals to the nacelles - good idea as you'll be using a much stronger motor.  I thought about adding them also, but I'll likely not need to go with much more than a single loop of 2/32nd or 1/8th.  I did, however, inlay 1/32nd sheeting into the front lower bay for peace of mind ;).  Don't forget to face the prop plug opening with thin ply.

Don:-
The net incidence, per plan, is only ~2°.  I doubt that 1.5 to 2° can effectively be added with tabs without looking really funky.  You vid, where it seemed to want to fly, shows that you're nearly "there".

Try adding the tabs to the main outers again, or make up small ailerons - full length of the outer panels - out of Post It or whatever (you want it flexible), to give you ailerons about an eighth of an inch wide.  Reflex them UP about 1/16th and try again.  At the small scale your working at, you need all the angles to trick Mr. Reynolds.

I have a canard slope soarer (40" span, rc) that was designed with a slightly reflexed airfoil that flies beautifully, but nowhere near as fast as I would like.  The airfoil is a CJ-3309. which is flat bottomed with reflex, some Phillips entry.  Well... I wanted more speed so I built another with a semi-symmetrical 'foil with the same thickness (IIRC, 9%) and about the same amount of TE "kick" (raised the ailevators about 1/8th).  The canard on this model is fairly small, fixed and close coupled.  Didn't want to fly, but I could force it to stay in the air (rc - lots of elevator control).  Moving the CG just made the "stall" come sooner.  Added Gurney flaps to the canard which helped a bit but the real help was cranking up the ailevators another 1/8th (removed the Gurneys from the canard).  Got a greater speed range at cost of a slightly higher stall speed (brisk walking speed for an 18 yr. old ;)).

Difficult to assess a situation without being "hands-on" :-/...

Just a thought...

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 12th, 2014 at 4:07pm
Prop blanks marked and rough cut.
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Title: Re: Any Twin Cookup
Post by staubkorb on Sep 12th, 2014 at 4:11pm
Faces (pilots view of prop) cut.
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Title: Re: Any Twin Cookup
Post by staubkorb on Sep 12th, 2014 at 4:22pm
All that's left to do is thin down the hub, glue in a bushing, dope, fine sand and maybe cover/paint.  They weigh 0.58gm apiece.  Heavy props add nothing but weight to this model as they are very close to the CG and add mass in the roll axis.
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Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 12th, 2014 at 6:01pm
Pete...
The props look great.  Nice job.  I was looking at your blanks and was wondering if you cut the tips with a saw or just how you shaped the tapered tips. 

I was thinking of yogurt cup blades for mine, with aluminum tube hubs.

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 13th, 2014 at 4:44am
My prop blocks were laminated from 2 layers of soft (5.5 #/foot²) 4mm and a layer of 2.5mm medium (for the thin trailing edge.  I did the rough cutting on my ancient 571-5 Dremel Moto-Shop, but the tapered tips on these small thingies was done with a razor plane and careful sanding to a 4.8mm thickness.  The face taper (the 2.5mm layer) was taken down to the seam - the back side, down to about 1mm from the seam.

The face taper is a bit shallower that the back side.

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 13th, 2014 at 12:38pm
Thanks Pete for the explanation, I can see how the razor plane would be quite helpful on that. 
Tom

Title: Re: Any Twin Cookup
Post by Don McLellan on Sep 13th, 2014 at 4:31pm
Nice looking props Pete. 

Title: Re: Any Twin Cookup
Post by bigrip74 on Sep 14th, 2014 at 6:20pm
PETE:
NICE VIDEO
NICE WING TIPS
NICE PROPS
REALLY NICE SURFACE ON THE AIRPLANE

Great job Pete, I would like to aspire to be able to produce a clean build as so many here.
Bob

Title: Re: Any Twin Cookup
Post by bigrip74 on Sep 14th, 2014 at 7:08pm
I used another laptop that has Vista and was able to reduce the photos enough to post.

Proof that I did work a little on the Martin Maryland:

the first two are of the nacelle construction and the last is the left engine nacelle sitting in the correct position on the wing. Now to build the right wing and then possibly attaching everything together, but my main problem is deciding whether to cover before or after the wings are attached.

Decisions  :P

Bob
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Title: Re: Any Twin Cookup
Post by Colonel Manfred von Holstein on Sep 14th, 2014 at 8:36pm
Pete,

You carve a nice looking prop. I'm probably missing the obvious here but how do those ogee shaped balsa templates get used?

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 15th, 2014 at 1:52am
Bob...I'd think covering first would be a much easier task than assembled together.  But I don't know just what you had in mind for sure, when you say together!

Great to see the progress on the Maryland.  I'm still thinking about the Marauder...so we'll see.  The Rutango is progressing and I've completed one side of the fuselage with "0"degrees set on the wing saddle area.  So we'll see how that works out when I get all the components together.  I also finished the built up vertical stabs completed.  This also showed me that the center section of the wing needed solid formers between the root ribs for a bit stiffer wing.  Thinking of a detachable wing for this model for storage.  Running out of room to hang models in my limited space in the new place here in WA.

Pictures tomorrow...had the grandkids this weekend and wound up doing tie-dye "T"-shirts and no modeling. 

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 15th, 2014 at 6:49am

Colonel Manfred von Holstein wrote on Sep 14th, 2014 at 8:36pm:
Pete,

You carve a nice looking prop. I'm probably missing the obvious here but how do those ogee shaped balsa templates get used?

I had to go back a few messages to get what you meant ;).  Those parts are the sub-fins.  Once the fin/rudder assemblies are attached to the nacelles, the "rudder" portion hangs below the lower surface of the nacelle.  I wasn't able to measure the weight difference between the ones shown ans a built up one I made - so I went for the easy ones :).

Title: Re: Any Twin Cookup
Post by Colonel Manfred von Holstein on Sep 15th, 2014 at 11:24am
Okay. There are quite a few ways to layout and carve props.  Since those fins were in all the prop pics, I thought I was seeing something new but couldn't figure out how you used them.

Love what you're doing with this twin.  Carry on.

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 17th, 2014 at 7:28pm
Was able to work on the fuselage for the Rutango and got most of it done. Still have the nose block to laminate for the fuselage. 

Got the vertical stabs done and now I assembled the components in a mockup of the Rutango.  Here's the latest pictures.  I got lazy and didn't mark the center of the top fuselage formers for the stringer and I see that it's a bit off center and crooked.  Being a sport model I'll live with it. I need to remind myself to quit when getting tired and not try to get one more thing done!

Tom
mockup_of_wing_and_fuselage_components_1_001.jpg (62 KB | )
wing_nacelles___vertical_stabs_conponents.jpg (89 KB | )
mockup_of_wing_and_fuselage_components_3.jpg (49 KB | )
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Title: Re: Any Twin Cookup
Post by staubkorb on Sep 18th, 2014 at 9:07am
Looking GREAT, Tom!  Don't forget the supports for the vertical rear pegs!  Raising the TE about 1/4" from the stock position for your model should suffice for starters.  Are U gonna put the landing gear on it?

I've completed the tongue-in-groove mount for the wing on mine and will use two pairs of 3mm sq magnets to latch the TE.  I'm really having second thoughts about the removable wing though...

In a cartwheel landing, the wing "fork" will tear off the top of the fuselage.  There isn't that much of a transport benefit - the box will STILL be quite large what with wing sweep and the nacelles.  I'll probably go ahead and permanently glue the wing on once the decalage is set.

Winding the model wiil still pose a problem.. How does one wind (stretch) with that canard in the way - there is only about 3/4" clearance (on mine) :-/?  Winding with the wing OFF is an option...  I still have to figure out a stooge for this pup - don't have a resident one ;).

The removable wing would still be viable IF the inset is eliminated - that is, the fuselage/wing break is made at the fork point instead of the inner former.  That's the way I'll doit if I build another.

Photos to follow...

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 18th, 2014 at 11:02am
Thanks Pete... I was wondering about the motor anchor because I didn't see anything on the plan and noticed on Don's his vertical setup.  I was wondering about that very same winding problem.  I might be able to get my lovely wife to play "stooge" for me as Don does!  That would simplify things a bit. 

I did build the fuselage straight (Parallel to the datum line) from the fork former back to the trailing edge of the fuselage so the wing sit at zero incidence with the nacelles at about  1/16 down angle in relationship with the wing.

I was thinking of the magnets and a bamboo peg to anchor the leading edge to the former .  If built again I'd go with your suggestion to build the leading edge with a fuselage fairing and anchor there at leading edge.   

I'll show fuselage construction by itself later today.

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 18th, 2014 at 12:48pm
;) The gears are already churning for an e version at 2X for (GASP! CHOKE! ::) :D) rc :o...

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 18th, 2014 at 3:09pm
That would be killer!!! :D :o ;)

Tom

Title: Re: Any Twin Cookup
Post by Don McLellan on Sep 18th, 2014 at 6:55pm
Hi Tom,

More very good progress on you Rutango.  It looks great.

One thing you might want to consider is sheeting in the the first bay, on the bottom of the nacelles.  That is where mine broke (actually a couple of times) when is lawn darted in.  I think the prop catches the ground and transfers the impact load to the bottom of the nacelle. 

Don

Title: Re: Any Twin Cookup
Post by bigrip74 on Sep 18th, 2014 at 8:38pm
GREAT WORK [smiley=thumbsup.gif] PETE:  cannot wait to see this one finished and flying.

Bob

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 19th, 2014 at 9:17pm
Upon the insight gleaned from Pete's experimentation I modified the fuselage wing saddle area to be parallel to the datum line from the plans.  I set the saddle at zero incidence so the main wing will be at zero incidence as apposed to the canard at around 3 degrees positive incidence.

I have two pictures showing my modifications one with lines showing change and one without the lines to see the bones more clearly.

Tom
modified_main_wing_line_on_fuselage_1.jpg (131 KB | )
modified_main_wing_line_on_fuselage_2.jpg (112 KB | )

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 20th, 2014 at 7:33am
Photos of the prop clutches (Nason type freewheel), and the tongue-and-groove wing mount.  The wing mount looks, and IS, cobbled up as I did the thing as I went along - essentially "in the air".  I canted the "groove former" forward a bit to give me some wiggle room in the event that more or less incidence might be required.

For some reason, a couple of the photos are a bit out of focus - probably bumped the tripod or didn't get my hands off the camera fast enough after pressing the release (about 0.5 seconds from "press" till the auto focus kicks in).
DSCF6108_clutches.jpg (100 KB | )
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Title: Re: Any Twin Cookup
Post by staubkorb on Sep 20th, 2014 at 7:47am
One thing I came to realize  ::), is that the canard cannot be simply slid into the slot like the profile planes.  The fuselage and canard are compound shapes requiring that the slot be at least 3/16ths wide (and mine is a TIGHT fit already).  Easy to remedy by cutting the carry-through down the middle with a compound line that automatically realigns when rejoined.  A cross-brace or two in the fuselage, flush with the slot bottom will keep the unit on an even keel.

The fuselage with top deck and the wing "slotted" in place:...


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Title: Re: Any Twin Cookup
Post by staubkorb on Sep 23rd, 2014 at 3:40pm
Nason clutches glued on the props (hope I got them on the right way!), and finishing up the prop plugs (nose plugs).  Glueing (epoxy) a 3mm tube without gumming up the works was not that easy.  As soon as the dope (banana oil) dries on the plugs, I'll mount the props.

Since I use "O" rings on small motors, I won't be incorporating a winding hook on the prop shaft - it'll be tricky enough winding over the canard without a prop in the way.  I hope to get a few test "flights" with the skeleton fuselage within the next day or two.

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 23rd, 2014 at 9:02pm
Keep us posted on your progress with the bones fuselage glides ...Pete!

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 25th, 2014 at 5:10am
Prop assemblies are complete and work the right ways (I think - things get complicated when one unit has to work "bassackwards").  If the wind dies down by this evening, I should get a test or three with the stick fuselage.  Rubber motors will be a ~10" loop of 3/32nd Tan SS per side - hook-to-peg is 7".

I'm still undecided about a landing gear...  The model looks cool with the wheels, but weight and drag are BIG un-incentives.  A plug-in system is an alternative, but adds even more weight by means of the needed supporting structure.

I'm up to 23 grams with the fuselage still to cover.  Landing gear will add at least 2 grams and the covering/doping another 3-5 grams.  Any other decorations will up the tally :-/.  Going by the RoT of 0.5gm/inch², I'm still well within the "limit", especially if one counts the area of the canard which is a load carrying surface.

Let me get the beast flying first...

Very low participation on the various Forums.  I guess most are/were at Geneseo (GGG) or finally have some flying weather?

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 25th, 2014 at 10:26am
Pete...
(Very low participation on the various Forums.  I guess most are/were at Geneseo (GGG) or finally have some flying weather?)

I think you've nailed the low participation situation. 

I'm not able to work on the models with some house maintenance issues  and my visiting 86 year old Mother visiting from So. Carolina.  So building will have to take a back seat for a bit.

You're making great progress on the 75% Rutango.  I really appreciate your experimenting which allows me to build with your insights incorporated into my build.

Tom

Title: Re: Any Twin Cookup
Post by JimM on Sep 25th, 2014 at 7:57pm
>I guess most are/were at Geneseo (GGG)

Well, some were. I can send report/photos; anyone interested pls contact me at [email protected]

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 25th, 2014 at 8:59pm
Jim,

Feel free to post some pics and videos on the Events board.... We'd love to see them!
Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 27th, 2014 at 11:29am
Latest glide test today, with the fins attached (I actually got them on straight!) and the corresponding CG adjustment resulted in a LOOONG floating glide from shoulder height and a hint of left turn.  It nearly flew into the grill, but the turn "saved" it, landing only inches from the wall.   A bit later, a few glides with the prop units in place (and re-balancing - the props fully countered the weight of the fins :)) were very satisfactory and showed how critical the CG is (vid of the glide with props in place will be uploaded later).

I have some short motors made up and may try to get to the field later this evening for some power tests.  Weather conditions are nice, so it will be a toss-up whether to "fly" (Cloud Tramp, Senator, 4SSS) or "test"... ::).
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Title: Re: Any Twin Cookup
Post by bigrip74 on Sep 27th, 2014 at 12:35pm
Pete, I cant wait to see the video :D

Bob

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 27th, 2014 at 2:00pm
Ta-Daaa!

http://youtu.be/XBIonGrjBtI

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 27th, 2014 at 10:47pm
OUTSTANDING PETE.... great looking glide and very promising for powered flight.  I hope to put tissue on next week.

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 28th, 2014 at 7:01am
Today looks like a good day to fly, but upcoming construction to the house has put a twist to things (literally!).  Scaffolding was erected yesterday in the front while I was playing in the back, and the jerks did a bang-up job of twisting my satellite dish out of shape - they had assured us that there would be "kein Problem", but that we may have to temporarily relocate the dishes (Farraday cage effect).  Well, dish kaputt - has a permanent set - and a buddy is coming by later to try and re-form and relocate the thing to where it will at least do SOME good.  Insurance from the scaffolding company will buy me a new dish (they BETTER!).

The downside is that I'll probably be missing a beautiful day (NO wind at the moment) at the field >:(, and the small upside is that I'll be able to watch "Falling Skies" and "Sons of Anarchy" in the evening ::).

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 28th, 2014 at 1:40pm
The challenges of everyday life!!!  Good luck with the solutions! [smiley=thumbsup.gif]
Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 28th, 2014 at 5:01pm
Sat. dish is re-located and sorta straightened.  Had to set it up about 3° off "normal", thanks to the new shape >:( - but at least it works.  Missed out on a fantastic opportunity at the field >:( >:( :'(.

Now I can get back to the important stuff ::)

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 29th, 2014 at 9:37am
Tom,
if you haven't covered the wing yet, add gussets behind the "fork" former - especially if you opt for  removable wing.

I didn't... >:(

Title: Re: Any Twin Cookup
Post by Don McLellan on Sep 29th, 2014 at 11:00am
Nice looking glide Pete.  It will be a great flyer.

Don

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 30th, 2014 at 10:11am
Thanks Don.  I've got the 3/32 motors in and am just waiting to see what the weather is going to do.  Forecast is for showers and calm.  Breeze <2ms at the moment (good) but towering cumulus all around and humid.  Any wet is not good when one is on foot with cardboard boxes and tissue covered airplanes.  I won't be taking heavier motors today, but WILL be taking a Cloud Tramp, the 4 SSS and a glider (gotta get some FLYIN' in!).

I've bent up the main LG out of 0.8mm wire and wii bend the nose leg this evening.  I probably will not ever fly the model with the gear plugged in (added weight will be about 1.5 - 2 grams including the fuselage reinforcement) as the model  weighs just a hair under 30 grams already (stick "fuselage").  The projected weight with the "real" fuz should be about the same (AuW with uncovered fuselage is 23 grams).

We'll see...

Title: Re: Any Twin Cookup
Post by Tom Akery on Sep 30th, 2014 at 10:32am
Found this picture of Bill's own Rutango on an old SFA thread about the third post down... Click Here
When you click on the link a box will come up to print page, click cancel and the page will come up!
A nice silver and red scheme. Bill has a lot of interesting creations!

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Sep 30th, 2014 at 2:46pm
Thanks for posting that link, Tom.  I was aware of the CU (I built the Bug-Ami for it), but no one knew if the plane had flown.  It DOES appear to have the wing TE raised higher than what is shown on the plan - the LE appears to bisect the top longeron rather than having the lower camber running parallel to it.

I made it to the field late this PM.  Dead calm and humid (it was humid all day).  I unfortunately left the house without checking my hygrometer...

By the time I got to the field and the motors wound (only 70 turns by hand), prop pins in place, the wing strapped onto the skeleton fuselage and the balance re-checked (H'mmm, a bit nose down - off with a bit of nose weight...), the covering was wrinkled.  By the time I got to my release point (20 meters away) the covering looked like a piece of laundry fresh out of the washing machine >:(.

Keep the above sequence in mind...

The good news, the RUTANGO flys... trouble is, the humidity added about a gram to the main wing.  The PROP PINS are short lengths of music wire (go back to my prep sequence) and are ahead of the CG.  What's that spell?

Yeah, it was a bit tail heavy at launch but not dangerously so.  70 hand turns on new motors is also not ideal, but the short, about 7 seconds, flight was still "OK".  No diving tendencies or other untoward antics and the "burst" maintained a positive attitude.  Slight left turn evident.  I put the plane back in the box.  I DID catch a bit on video.

The props seem to work OK.  Thrust appears equal and 3/32nd rubber appears to be the right size for this airframe.  More turns are definitely needed.  Downthrust was/is that which is designed into the nacelle sides (about 2.5°).

One thing is evident.  The nacelles, in larger variants of this model, will seriously benefit by the addition of diagonals between the cross pieces - at least back to the wing LE.  My nacelles were already twisting on 70 turns - no doubt compounded by the soggy tissue.  Banana oil (3 coats) is on all surfaces.  Would more be helpful or should I go for a coat of normal dope?

Got two flights in with the "Cloud Tramp" and the "4 SSS" that were not worth writing home about.  The humidity had softened up all the wood to the point that I could have rolled the stabs and rudders into tubes (they are DOPED).

When I got home, I looked at my hygrometer - 95%.

Title: Re: Any Twin Cookup
Post by staubkorb on Oct 1st, 2014 at 9:04am
I'll try to do things properly today.  Re-checked the balance with rubber, props (MINUS prop stoppers ;)).  Needed about half a gram more to the nose than before I "corrected" the balance yesterday - a fair indication that the rubber bias is not too bad (about 40/60 - forward/behind CG).

I might be able to get out today IF my appointment doesn't take too long.  It's not quite as humid as it was yesterday (that can change dramatically by late PM) and the breeze, tho there IS one, is "straight down the runway".  Will try with at least 100 turns (and someone to video the attempt - I only caught where the plane "settled in" yesterday).

Title: Re: Any Twin Cookup
Post by staubkorb on Oct 1st, 2014 at 1:18pm
Follow ups to my Rutango experience will be in the "How's it Flying" board.

Title: Re: Any Twin Cookup
Post by Tom Akery on Oct 1st, 2014 at 8:27pm
Pete...in your build of the wing, did you build any washout in the wingtip panels?  I was wondering about the +1/16 incidence in the attachment of the wingtip to the nacelles.  Would the wingtip mounted aligned with the bottom of the nacelle equal washout when the center section was mounted and the nacelle attached to the wing center section at the -1/16 incidence giving the nacelle the downthrust you specified earlier.

So... any need for washout on the wingtip panels?  Or just mount the wing to the nacelles at the +1/16 incidence (both the center panel and the outer panels)?

Just thought I'd ask this... ::) :o :D ;)

Tom

p.s. starting on covering tomorrow.

Title: Re: Any Twin Cookup
Post by staubkorb on Oct 2nd, 2014 at 12:42am
That 1/16th incidence was "left in" to counter what I feel is a bit TOO much incidence in the canard (something like a skosh over 5° referenced to the datum).  As I already had the fuselage framed up and all square, I didn't want to start butchering things up.  The trailing edges of the tip panels AND the TE of the center section are FLUSH with the rear bottom of the nacelles and the leading edges are blocked up 1.5mm at the rear edge of the LE (sounds trickier than it actually is).  Using 1/16th should pose no problems (it's a bit more than 1.5mm - closer to 1.6).  Just make sure that they are equal.  The wing itself is at 0° to the datum (airfoil bottom)!  The "incidence" is really only there to kill the illusion that the nacelles are pointing "up".  Shape your LE as carefully as possible - the center lines on the rib templates are there for a reason.

I did shrink in a bit of washout in the tips - 1.5mm at the tip rib.

Got the plug in main gear "box"' built into the fuselage last night.  Discovered that precisely that point is likely the best holding spot for launch (make sure you beef up the area where you choose to hold for launch).  I've found that the fuselage will benefit GREATLY thru thorough gusseting - I've knocked out quite a few uprights AND x-members in spite of double/triple gluing.  The fuselage, even tho it does not have to cope with rubber torque/compression, still takes a beating (Maxout and other fliers adept at handling F1d planes won't need this tip ;)).  Nose gear is next, then covering and "glassing" the 'pit.

Title: Re: Any Twin Cookup
Post by staubkorb on Oct 6th, 2014 at 9:22am
I've added receptacles for removable LG to the "3D" fuselage and made up the gear legs.  Wheels will be balsa.  The wire bending turned out quite well, considering the compound bends.  I also added the two magnets (3mm x 1mm square) at the rear end for wing retention.  Two additional will go in the center section TE.

Title: Re: Any Twin Cookup
Post by staubkorb on Oct 7th, 2014 at 10:25am
Some photos.

First one is at the field for the maiden 70 turn motorized test.
Photos 2-4 shows the results of a rainy and windy day.
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Title: Re: Any Twin Cookup
Post by staubkorb on Oct 7th, 2014 at 10:41am
Totally disassembles for transport.  Might even help to reduce damage from "unusual attitude" arrivals.  the canard is split in the middle with an offset cut, and 3mm x 1mm edge-on magnets plus "scabs" hold the halves together and in alignment.

Main wheels are laminated with the nose wheel still to be cut (the legs were somewhat of a pain to bend accurately).  Glassing the cabin, covering the bottom nose section and some final trim deco will have her ready for final set-up.
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Title: Re: Any Twin Cookup
Post by Tom Akery on Oct 7th, 2014 at 11:59am
Pete... your engineering is stunning!  Well done.  What a great looking model.  I'm definitely going to have to steal some of your ideas!!!! [smiley=thumbsup.gif] I've been layed up for a bit with a bum knee from working in the backyard...

Hope to get back to building soon.

This is a great looking model.  Love it!

Tom

Title: Re: Any Twin Cookup
Post by Don McLellan on Oct 8th, 2014 at 8:20pm
Excellent work Peter!  Agree with Tom, going to steal some of those ideas.

Hope your knee is getting better Tom.

Don

Title: Re: Any Twin Cookup
Post by Tom Akery on Oct 8th, 2014 at 8:50pm
Thanks Don...on the mend!  Should be back to it soon!
Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Oct 14th, 2014 at 12:08pm
OK, I'm back ;)!  Got involved with a few other matters...

Bum knees are a bummer!  Makes EVERYTHING a bit more difficult...

Thanks for the kudo's!  Been working out a twin stooge for this pup that I should be able to use on any twin with vertical posts - somewhat adjustable for the size planes I THINK I will build to (we all know how that will end ::)).  At this time, I don't really plan on building any twin with a >32 to 36" span, so I'll be making the anchors with enough adjustment for the nacelle span.

Painting up the wheels and have cut out a cellophane (actually more of a vinyl) windscreen.  I laid a sheet of the stuff (wrapping from a birthday card) around the fuz and traced the outline with a sharpie pen.  Soon as I feel that my hands won't shake the fuselage apart, it'll get glued on.

Weather was nice today except for the wind.  It was a bit more than what I prefer for testing, and a walk by the field yesterday met with a freshly mowed and very soggy view.  The rc'ers were out in force.

Hopefully tomorrow (if the stooge gets finished)...

Title: Re: Any Twin Cookup
Post by Tom Akery on Oct 14th, 2014 at 9:08pm
Glad to hear your back.  Knee is better did some experimentation today with tissue and EZE Dope to see how it will work on the Rutango.  But could only sit for a few minutes till I had to straighten out the knee again. So this looks like I'm going to be doing a "Work a little" "Move a little"  till I can sit for a bit longer. 
Your scheme on the Rutango is very nice!  I especially like the registration letters! [smiley=thumbsup.gif] ;D ;) 8-)
Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Oct 15th, 2014 at 6:35am
Good to hear that the knee is improving.  My biggest pain is my back and bill collectors :D!

Do make a comprehensive series of tests with that EZE Hope.  I'm still trying to keep an open mind about the stuff, but so far, the seeming majority agrees that it is cra* - including Monz.  Hopefully, it will turn out to be a simple matter of experience with it - my first year of working with aircraft dope was a disaster.

Spray it if you can...

I was kinda wondering if anyone would catch the registration thing.  You're the first ;)!

It's beautiful atm but a bit blustery.  Trying to get the stooge built to the point that I can use it this afternoon ( I REALLY do need a small milling machine, the Dremel Workstation just doesn't cut it).

Title: Re: Any Twin Cookup
Post by Tom Akery on Oct 18th, 2014 at 9:43pm
Got some tissue on the Rutango today.  Still need to cover the prop blocks and vertical stabs & shrink the tissue.  I don't plan on adding landing gear.  Still plan on adding some trim tissue.  A little white for a Red, White & Blue look.  Prop blocks needs to be finished also then decide about the props to carve or not to carve?.  Then to figure out the winding stooge...how's yours coming along, Pete?

Here's the pics...
Tom
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Title: Re: Any Twin Cookup
Post by staubkorb on Oct 19th, 2014 at 7:22am
Nice vibrant colors, Tom!  Domestic?  I can't get bright schemes like that with the materials I have to hand without going to full acrylic.

I think the "stooge" issue is one of the reasons that more multi-motored models remain a rarity - especially odd configured ones.  The idea I had for a general purpose twin stooge didn't pan out for this particular model, but may work for more "normal" configs.  I've cobbled a semi rigid one together where the pin arms reach over the nacelles (twin pins) without fouling the fins.  The removed wing slips into the unit, pins inserted and then wound - both nacelles are fixed in the unit.

As noted, my wing is removable fore storage/transport and winding.  My thoughts are that there is less stress and damage potential for the rest of the airframe - namely the foreplane.  The main body is also rather bulky wihch would require deeper standoffs than what I have used.

Pics forthcoming when the epoxy is cured and the stooge is tested.

Weather has taken a turn for the better, so I was out at the field yesterday for some more testing - or so I had hoped...

Leaving the house with a couple of gliders (for testing the drift) and the Rutango/skeleton fuz, my olfactory sense was assaulted by the seasonal freshly FERTILIZED fields syndrome (natural , organic cr*p used here).  A cataglider was "offered" in hopes that off-field excursions would be the exception - it wasn't >:(.  Said cataglider is now part of the natural fertilizer, having landed squarely into a clump of muck.  I'll have to wait for the next good rain/dry spell, or a totally calm day before any FF flights can be made. >:( >:(

Title: Re: Any Twin Cookup
Post by Tom Akery on Oct 19th, 2014 at 12:15pm
Pete...it is domestic and applied dry except for the wingtips.  All those curves needed it to be wet.  I had to be very careful.

I look forward to your stooge info and pics.

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Oct 19th, 2014 at 4:24pm
The color saturation is much nicer than what is obtained with Esaki.  As you're not going to incorporate landing gear (I prolly won't fly with mine on), I hope you sheeted the first couple of bays on the bottom.

I've completed the provisional stooge.  The upper arms provide the primary retention and are long enough to reach the rubber posts.  The slots in the base - slotted and slightly oversize to compensate for misalignment and ease of pin insertion - provide lower fixation.  Stooge retaining pins will be semi-permanently tied to each post with string.  Not yet photographed are the foam rubber strips that are glued to the base for airframe/wing protection.

The upper arms swing out of the way, once the retaining pins are pulled, to alleviate wing removal (or just slide the wing forward - which could be problematic).  One just has to remember to insert the prop retaining pins when the props are attached...
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Title: Re: Any Twin Cookup
Post by Don McLellan on Oct 19th, 2014 at 10:03pm
Hi Tom,

That is an exceptionally bright, well done Rutango! 

Looking forward to the pics of it completed.

Hi Peter,

Can you post a pic or two of your model in your stooge.  My stooge (read wifey) really, really wants to get out of the stooging game.

Don

Title: Re: Any Twin Cookup
Post by Tom Akery on Oct 19th, 2014 at 11:20pm
Thanks Don and Pete....

Pete, I'm with Don, I'd like to see the wing in the stooge. Would help me understand a bit better the arrangement.

Where do you locate the prop retaining pins?  Do you have them tied together  so they can be pulled simultaneously when ready to launch?

My wife hasn't been too receptive to the stooge chores, might be related to the name!!! :D ;D ;)

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Oct 20th, 2014 at 6:53am
You guys are really very lucky to HAVE a "people" stooge, even tho they might (don't) particularly like the job  ;) ;D (after all, it's work and the only satisfaction they have is the "thank you" and maybe a dinner plus seeing YOU enjoy yourselves).  The oikes here (to coin a Monz description ;D) aren't afraid to grab one of my models :o, but are terrified to stooge one :-?.

Photos of the wing-in-stooge:

I have to increase the thickness of the base, as I clamp my stooge to a table at the field and the fins hang about 1.5mm below.
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Title: Re: Any Twin Cookup
Post by staubkorb on Oct 20th, 2014 at 6:57am
Here are a couple of shots of the prop stoppers and pull lanyard.  I position the lanyard so that it is over the canard when ready to launch - the thrust-lines are above the canard, which could cause a pull from below to foul/damage the foreplane.

Also, a shot showing the fuselage on the wheels.
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Title: Re: Any Twin Cookup
Post by Tom Akery on Oct 20th, 2014 at 9:29am
Thanks Pete...really clarifies my understanding of the setup. 

Very ingenious arrangement.

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Oct 20th, 2014 at 12:44pm
[smiley=thumbsup.gif]Are you gonna use a detachable wing?  If not, then a two-tier setup will have to be made with the trough in the middle deep and wide enough to clear the fuselage.

Title: Re: Any Twin Cookup
Post by Tom Akery on Oct 20th, 2014 at 5:13pm
Yes...I'm planning on using the detachable wing.  But I can see the difficulties with the leading edge of the wing cupping the fuselage.  I'm contemplating using a peg in the wing and socket in the bulkhead on the fuselage.  It definitely would have been better with the bulkhead moved to wing leading edge.  Should have done that before covering....


I've just finished the first coat of Ezedope/water 50/50 solution brushed on.  Actually came out very nice.  I'm going to add another thin coat after a day of drying.  Been raining up here in the No. West and I want to give it appropriate time to dry!

Tom

Title: Re: Any Twin Cookup
Post by Tom Akery on Oct 24th, 2014 at 10:17am
2nd coat of EzeDope was applied and I'm not real satisfied with the results.  The tissue has tightened up nicely and there are almost no wrinkles in the application of the tissue.  I like that! But the finish has left little white "hair like strands" 1/16 or so in length.  I'll try to get a close up picture to show you.  From a distance it looks ok, but close up not so good.  I did apply it with a brush instead of and airbrush.  So I'll give the airbrush a try on the next model with a 70/30 water/EzeDope mixture as suggested by Sciggs on HPA, to see if that works better.  So much for EzeDope! 

I've also decided against a knockoff wing arrangement.  I just can't see that happening without major damage to the fuselage with the existing wing-fuselage joint!

Kinda lost my building mojo, so I've got to finish the props, prop blocks and windshield/side windows of cockpit to complete the Rutango.  I do like the lines of the model very much.  If this one flies there may be another Rutango in my building future with several modifications to the wing joint!
Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Oct 24th, 2014 at 12:57pm
You might want to reconsider the fixed wing, if not for the somewhat easier transport, but for the winding ease.  Just provide for a positive "wing lock".

I got a first glide test ith the "3D" fuselage late this afternoon in the back yard.  The incidence was a bit off n the main wing, but there was no damage done.  A sliver of a razor blade between the magnets seemed to do the trick, as the resulting re-glide went clear across the yard (props and rubber on board).  The landing was very smooth and wings level.  I'll have to wait till tomorrow to get a flight at the field.

The plane is about two gramms lighter with the 3D fuz than with the stick thingy.


Title: Re: Any Twin Cookup
Post by Tom Akery on Oct 24th, 2014 at 9:37pm
Sounds great Pete.  I guess some sort of locking setup would work as well and as you say facilitate winding and carrying!  Thanks for the input.

Here's the pics of the EzeDope on the wing(red) and the stab (blue)... It may be due to my application, but looks like it doesn't completely dissolve in the dilution of 50/50 water/EzeDope.  Or I applied it too heavy and the drying cause a bit of depositing on the thicker sections of the application.  Going to try the airbrush before I give up on it.  I do like the hardness and tightness of the tissue using this though the white flecks is a bit of a problem.
Tom
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Title: Re: Any Twin Cookup
Post by staubkorb on Oct 25th, 2014 at 5:24am
Not sure what you meant by "it doesn't completely dissolve in the dilution...".  Sis you add pigment to the EZE (the red looks pretty opaque)?  The stuff DOES tighten the tissue up nicely and seems to be a lot more moisture resistant, but I 'm still not quite convinced whether it provides the torsional stiffness that a REAL dope finish provides.

Have you tried painting over the stuff yet?

It was pouring this AM and there is no hot water (AGAIN no prior notification about construction in house).  Got turned off as I was in the shower >:( >:(.   Wind forecast is also not that favorable, tho atm it's calm (and soggy).

Title: Re: Any Twin Cookup
Post by Tom Akery on Oct 25th, 2014 at 10:49am
Hate it when that happens...losing the the hot water in the shower! Weather is changing here in WA as well.
Had a major rain storm got 1 inch in 1 hour.  Really wild for a CA boy!

I'm going to try to spray a light coat of EzeDope with the Airbrush to see if this clears thing up!.  Got the vertical stabs covered and the prop blocks covered.  Still have the propshafts and props to add.  On this one I have room for 6 inch props.  So probably going the lazy root and use two Peck 6" grey props.

Tom

Title: Re: Any Twin Cookup
Post by staubkorb on Oct 27th, 2014 at 1:06am
I got the glazing on the fuselage, plus a bit of trim in the form of an anti-glare panel and side accents.  I used a cellophane-like plastic about twice as thick as cigarette wrap, glued on with glue-stick and fixed with canopy glue.  I'll probably add more detailing after I get the final flight trim done.  I'm also considering putting a coat of EzeDope on the plane (but I'll wait for Tom to play "airbrush guinea-pig" ;D).  I gotta find a way to beat the humidity here.

Essentially, this build is complete.

Title: Re: Any Twin Cookup
Post by staubkorb on Oct 28th, 2014 at 8:23am
FINISHED except for a trim stripe or two.  One bit of striping (either paint or tissue) will go around the cabin - the cutting guide marks didn't wash off.  I guess the OHP marker I used worked "permanent" on the plastic used.  No additional ballast was needed to maintain the CG and there is no noticeable shift with or without the landing gear.  The gear will be used onl for indoor flying - the wheels roll SO smoothly that I had trouble keeping the model stationary for the photos!

A pleasant surprise was the final weight of 26.7 grams (w/o rubber and with landing gear) - 29.8gm with the short motors - where my goal was for under 30.  This will allow me to do a bit more "moisture proofing".

Follow-up flight testing with the full fuselage might be possible tomorrow
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Title: Re: Any Twin Cookup
Post by Tom Akery on Oct 28th, 2014 at 10:05am
Great looking Rutango, Pete...

I was thinking of trim lines as well.  Some white to the red and blue!

Looking forward to your next trim flights.
Tom

Title: Re: Any Twin Cookup
Post by Don McLellan on Oct 29th, 2014 at 11:30am
Beautiful Pete! 

Title: Re: Any Twin Cookup
Post by Tom Akery on Oct 29th, 2014 at 10:08pm
Got some more done on the Rutango today.

Props and propblocks finished
Vertical Stabs doped and attached
Cockpit glazing in place

I used the EzeDope straight with a brush on the vertical stabs.  It went on much better.  Water soluble it is but the water tends to make the EzeDope bubble. 

I used Aleene's Tacky Glue to attach the glazing on the side windows and windshield. 

I decided that with this sport model the yellow props only added to the bright color scheme!

Still have to make the wing attachment setup...giving this some more thought.

Here's the pictures

Tom
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Title: Re: Any Twin Cookup
Post by Don McLellan on Nov 2nd, 2014 at 12:29am
Hi Tom,

As usual, very nice work!

And as mentioned before, you'll be able to pick this one out against any colored sky.

Don

Title: Re: Any Twin Cookup
Post by Tom Akery on Nov 2nd, 2014 at 1:16am
thanks Don,

I'm kinda growing fonder of the scheme each day. Just have some trim to add and finish the wing attachment and I'll be set.
Tom

Title: Re: Any Twin Cookup
Post by Tom Akery on Nov 9th, 2014 at 12:12am
You know how you think you've completed a model and you done everything you'd plan to do...then you take some pictures of the plane to post and you see a glaring missing element!

TAAA DAAAA....I've just done it!  Can you see it?

Here's the pictures,  I still have to build a stooge for this beauty!(I kinda like it)

Tom
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Title: Re: Any Twin Cookup
Post by pb_guy on Nov 9th, 2014 at 9:54am
Nice trim. really goes well with the props.
ian

Title: Re: Any Twin Cookup
Post by Don McLellan on Nov 10th, 2014 at 8:20pm
Looks great Tom!!  But I was thinking you're still missing the Superman decal......

Don

Title: Re: Any Twin Cookup
Post by Colonel Manfred von Holstein on Nov 10th, 2014 at 11:37pm
That's a very vibrant and eye catching  color scheme!  [smiley=thumbup.gif] [smiley=thumbup.gif]

Title: Re: Any Twin Cookup
Post by Tom Akery on Nov 14th, 2014 at 1:58pm
Don,

These pictures are just for you!!!LOL ;)

Tom
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Title: Re: Any Twin Cookup
Post by bigrip74 on Nov 15th, 2014 at 9:45am
Tom, I love the Super Man motif. [smiley=thumbsup.gif]

Bob

Title: Re: Any Twin Cookup
Post by staubkorb on Nov 18th, 2014 at 7:07am
[smiley=tekst-toppie.gif]
What's the final weight (w/o rubber), Tom?

Title: Re: Any Twin Cookup
Post by Tom Akery on Nov 18th, 2014 at 11:20am
Pete,

In the moves over the last year, the one box that got lost had my assortment of aluminum and brass tubes, scale, and several tools.  So I don't have a scale to weigh the model yet.  I hope to replace the scale soon...Harbor Freight Tools has one that goes to 0.1 gram registration for about $10.00. 

I hope to have a weight for you soon.

Tom

Title: Re: Any Twin Cookup
Post by Tom Akery on Jan 7th, 2015 at 2:23pm
Just came across this link to a great looking twin designed by Mike Stuart and he's made it available for free download.  Beech Super King Air 200.  Beech Super King Air 200 plan

Mike has made a great model that is really tugging at my build strings!  Such a great looking twin that has such great promise.  Thanks Mike for your inspiration, generosity and sharing such a great plan.

Sky9pilot
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Title: Re: Any Twin Cookup
Post by Tom Akery on Jan 10th, 2015 at 3:23pm
Bob,
Had to share this with you as some inspiration for the Havoc!!!!
Tom
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Title: Re: Any Twin Cookup
Post by bigrip74 on Jan 10th, 2015 at 3:54pm
Tom that is a nice pic, do you have one for the Martin Maryland?

Title: Re: Any Twin Cookup
Post by Tom Akery on Jan 11th, 2015 at 12:05am
Bob,
Not for the Maryland...learned how to make a simple one...here it is!
Sky9pilot

p.s. I see I've a lot to learn still!
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