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Cookup Peanut or dime Scale 2017.11. 23-2018.2.28 (Read 53418 times)
Reply #682 - Feb 20th, 2018 at 8:06am

New Builder   Offline
Senior Member
Amherstburg, Ontario, Canada

Posts: 699
****
 
Tom - Thanks for the encouragement and I'll definitely be back. I'm a bit short on patience these days but all will be well soon.
New Builder
Mike
 

Have no fear of perfection - you'll never reach it. (Salvador Dali 1904 - 1989)
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Reply #681 - Feb 19th, 2018 at 11:04am

Sky9pilot   Offline
Administrator
Stick & Tissue
Kelso, WA 98626 USA

Posts: 9936
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Mike...sorry to hear about the physical problem.  Take care of your eyes!!!  The models will be there when you're ready to return.  Hang in there buddy.  Our thoughts and prayers go with you for a full and safe recovery!
Tom
 

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Reply #680 - Feb 19th, 2018 at 8:00am

New Builder   Offline
Senior Member
Amherstburg, Ontario, Canada

Posts: 699
****
 
Mr. Mulligan
Gotta take a break from all this until my eye is completely recovered. I keep causing more work than progress. Be back soon.
New Builder
Mike
 

Have no fear of perfection - you'll never reach it. (Salvador Dali 1904 - 1989)
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Reply #679 - Feb 16th, 2018 at 9:07pm

MKelly   Offline
Senior Member
Helotes, TX

Posts: 551
****
 
pb_guy wrote on Feb 16th, 2018 at 8:47pm:
Mike, if those blades have no twist, then I would be aiming for 40 to 45°'s.
Anyone else have a suggestion?
ian


Ian, the blades have some twist carved into them following the template on the plan, about 3deg positive at the root, neutral at mid-span and about 8deg negative at 80% span.  The plan says to slot the hub to hold the root of the blade at 20deg positive.

Mike
 
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Reply #678 - Feb 16th, 2018 at 8:59pm

MKelly   Offline
Senior Member
Helotes, TX

Posts: 551
****
 
Most free flight props use a Pitch/Diameter (P/D) ratio between .9 and 1.6, with most plastic props between .9 and 1.1.  I'm using a P/D gauge sold by Retro-RC.  This is a new tool for me - I've been using plastic props but after my WestFAC experience last fall I think I need to learn more about props (and motors!) to get the most out of my models.  From what I've read, slower, draggy high-lift models (like the Waco) fly better at the lower end of the P/D range and faster, cleaner models fly better with higher P/D props, but that is second-hand knowledge for me at this point.

What the P/D gauge tells me is that my technique for aligning the blades to the hub needs some work - one blade is .6, the next one is 1.2, and the third blade measures .8 P/D!  I went back and measured the root angle of each blade using drafting triangles and printed paper triangles and found the roots were at 20deg, 30deg and ~25deg respectively (the plans call for 20deg root angle).

So, for the flight props I need to make a jig that will cut the slots accurately to 30deg, and a jig that will keep them that way during installation so that I end up with a P/D of 1.2.

And yes, Max is a new addition to our household, and a significant contribution to recent slow progress on the Skyrocket...

Mike
 
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Reply #677 - Feb 16th, 2018 at 8:47pm

pb_guy   Offline
Senior Member
So I'm just a kid at heart.
Youbou, BC, Vancouver Island

Posts: 1199
****
 
Mike, if those blades have no twist, then I would be aiming for 40 to 45°'s.
Anyone else have a suggestion?
ian
 
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Reply #676 - Feb 16th, 2018 at 6:14pm

LASTWOODSMAN   Offline
Senior Member
REAL PLANES HAD ROUND
ENGINES AND TWO WINGS
Windsor, Ontario, Canada

Posts: 1440
****
 
I like that bench test demonstration of your spinning prop motor run.  Once you measure the P pitch and D diameter of the prop, then what do you do with that measurement ?
     I see your new little black lab puppy ...  Wink
LWM
Richard
 

OH, I HAVE SLIPPED THE SURLY BONDS OF EARTH ... UP, UP THE LONG DELIRIOUS BURNING BLUE ... SUNWARD I'VE CLIMBED AND JOINED THE TUMBLING MIRTH OF SUN-SPLIT CLOUDS ...
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Reply #675 - Feb 16th, 2018 at 2:43pm

MKelly   Offline
Senior Member
Helotes, TX

Posts: 551
****
 
I carved some spare blades and assembled the prop on the mockup freewheeler for some bench tests.  The plan says to mount the blades with the hubs at a 20-degree angle, which I did.  This makes for a very low-pitch prop.  The bench test runs OK with 3x hook-peg loop of 3/32" rubber (10.5" loop) wound to 1000 turns, but doesn't move a lot of air.

Video here:  https://www.youtube.com/watch?v=HhMinBTyphE&feature=youtu.be

I think I'm going to measure the P/D of the prop and consider increasing the blade angle before assembling the flight props.  The flight props will be mounted on S-hook shafts.

Mike

 
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Reply #674 - Feb 14th, 2018 at 3:03pm

LASTWOODSMAN   Offline
Senior Member
REAL PLANES HAD ROUND
ENGINES AND TWO WINGS
Windsor, Ontario, Canada

Posts: 1440
****
 
     Well Mike I must say, well done.  When the plane runs out of rubber power, and the Clutch Dog slips away from the Drive Power Plate's Drive Pin, and the prop spins freely in the "relative wind"  of the glide, being disconnected from the rubber motor, the rubber motor can then not end up being would backwards from the slipstream, which would produce a tremendous drag, which would impede the glide phase of the flight.  I am eagerly awaiting the flight results ...
LWM
Richard
 

OH, I HAVE SLIPPED THE SURLY BONDS OF EARTH ... UP, UP THE LONG DELIRIOUS BURNING BLUE ... SUNWARD I'VE CLIMBED AND JOINED THE TUMBLING MIRTH OF SUN-SPLIT CLOUDS ...
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Reply #673 - Feb 14th, 2018 at 10:36am

MKelly   Offline
Senior Member
Helotes, TX

Posts: 551
****
 
Richard,

You've pretty much got it.  I used washers instead of the ball bearing race.  The two discs are the prop hub - no washers needed on either side of the hub.

Mike
 
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Reply #672 - Feb 14th, 2018 at 9:56am

LASTWOODSMAN   Offline
Senior Member
REAL PLANES HAD ROUND
ENGINES AND TWO WINGS
Windsor, Ontario, Canada

Posts: 1440
****
 
     Hi Mike - those are very good freewheeler pics   Smiley Smiley  of your "Skyrocket" plane in the Cookup Thread, showing your version of Mike Mulholland's freewheeler.   I see you are using a wooden (as opposed to a metal)
Power Drive Plate
with a little wooden
Drive Pin
that pushes on the
Clutch Dog
which spins the prop.   That little wooden
Power Drive Plate
has,  and is glued to,  a small
aluminum bushing sleeve
that extends forward a little from the front of the
Power Drive Plate
, and this
aluminum bushing sleeve
is in turn glued solidly to the prop shaft, so that the
Power Drive Plate
spins with the prop shaft.  The brass colored piece at the back of the Power Drive Plate, which sits between the plastic thrust button and the Power Drive Plate - is that two washers or an actual
Thrust Bearing (Ball Race)
with tiny ball bearings inside?
      Next question - sorry for so many questions - the two big laminated wooden circles discs - are they the "
noseblock
" or are they the "
center section
" of the prop to which the blades are glued ?    I see that these wooden discs have,  and are glued to,  an
aluminum bushing sleeve
which spins freely on the prop shaft, and this
bushing sleeve
extends out rearward past the rear of these laminated discs, and butts up against the slightly forward protruding
aluminum bushing
of the
Power Drive Plate
Are small washers needed here
as they spin against each other ?  That is where I thought there were washers in the first place.
      Have I got this right so far?  Sorry for so many questions.  It is a very neat little gizmo - I must learn how to solder ...
LWM
Richard
 

OH, I HAVE SLIPPED THE SURLY BONDS OF EARTH ... UP, UP THE LONG DELIRIOUS BURNING BLUE ... SUNWARD I'VE CLIMBED AND JOINED THE TUMBLING MIRTH OF SUN-SPLIT CLOUDS ...
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Reply #671 - Feb 13th, 2018 at 12:33pm

Sky9pilot   Offline
Administrator
Stick & Tissue
Kelso, WA 98626 USA

Posts: 9936
*****
 
Looks great and I think it'll work on my Walfisch Roland CII as well.  I redrew his illustration from HPA in CAD to see if it clarified the setup for me.  I was a bit confused about the nose block setup with the rear base for his Thrust bearing.  I see you solved that with the two brass washers on the brass tube.  I can see already my drawing is inaccurate because the clutch dog goes behind the prop shaft infront of the pin.  I revise it and repost.

Corrected drawing now! with the clutch dog showing proper location.  2/13/18 10:53 am

Tom
« Last Edit: Feb 13th, 2018 at 9:57pm by Sky9pilot »  

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Reply #670 - Feb 13th, 2018 at 9:27am

MKelly   Offline
Senior Member
Helotes, TX

Posts: 551
****
 
I built a mockup of Mike Mulholland's freewheeler to see if I could fit it in the Skyrocket and to see what it would weigh.  I think it's doable - my mockup weighed less than a gram and it'll fit with a small gap between the spinner and nacelle (which I'll need anyway for downthrust.  Here's a short video of it in action:

https://www.youtube.com/watch?v=DDy4ou68NRg

Note that before the spinner is installed the lever can be flipped over to make it lock in reverse rotation - you'll want to make sure you have it the desired way before installing your spinner!

Now to make two for the Skyrocket.

Mike
 
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Reply #669 - Feb 12th, 2018 at 8:15pm

Sky9pilot   Offline
Administrator
Stick & Tissue
Kelso, WA 98626 USA

Posts: 9936
*****
 
Neal...that's my plan to post in the current builds section. 
Thanks for the interest. Wink Cool
Tom
 

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Reply #668 - Feb 12th, 2018 at 7:35pm

Kerak   Offline
Senior Member
I Love YaBB 2.5 AE!
Roy, Utah

Posts: 1591
****
 
Hey Tom...why don't you post your Walfisch build here on this site for all to see...share with us?

Neal
 
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