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Very Hot Topic (More than 25 Replies) A New Challenge! XP-80 (Read 4711 times)
Kerak
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Re: A New Challenge!
Reply #10 - May 31st, 2018 at 9:28am
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Those old kit designs often utilized 1/16" sq for the leading and trailing wing edges...as well as for same in the empennage...and needless to say, they must have "known" the weight of the wood in their kits.  Huh  More often than not, especially for wing leading and trailing edges...I've hedged things by going at least with a fairly hard 1/16"x1/8"...or 3/32"sq on edge (leading edge)...for the very reasons you've described.

Even then, you're well-advised after wetting to pin the structure down while tissue dries.  Truth is...I'm holding my breath every time I deal with the process.  Smiley  Sometimes I even shrink a section at a time (hence the value of attaching the tissue to all available points)...in order to NOT put too much stress on a structure.  It's time-consuming, but I have had success in avoiding warps that way. Then of course...comes the same process all over again while doping.

Wing rib spacing is also a factor in relation to the size of wood used in the leading and trailing edges.  I suspect this is the issue with your XP-80 wing.

We've got some guys here on the site that can build the most delicate structures...and manage while covering to not turn them into potato chips...efforts to be admired!

My experience with pre-shrinking works well with delicate flat surfaces...but not with curved surfaces.  Try it with the empennage.

Neal
  
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alfakilo
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Re: A New Challenge!
Reply #9 - May 31st, 2018 at 8:07am
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I'm going to take your approach in covering this in small sections. The wing is giving me a little fight. I'm using Esake and I think it may be too "shrinky" for the wing leading and trailing edges. I used 1/16 for each and it seems the tissue is pulling those both in a little ending up in some ripple wrinkles.

I've never tried pre-shrinking. This may be the time for it.

Or use a different tissue. I bought some tissue from Michaels and tried it out. Seems fragile and doesn't shrink much. Maybe that would be a better choice here.

I usually cover the bottom of the wing first but not here. I needed the wing on the fuselage so that I could work out the job of marrying up the intake to the leading edge. Once that is done, then I'll cover the bottom.
  
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Kerak
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Re: A New Challenge!
Reply #8 - May 31st, 2018 at 7:54am
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Wow!  Your XP-80 is absolutely fantastic, Alf!  And the work you've done on those intakes is spot on!

Yeh, if you're into exact scale...then you'd want all those mods to the plan, but there's something (at least in my mind) to continuing the legacy of the Comet folk...just my feeling about the matter.

I've been wondering how you planned to deal with the canopy.  You can always "pull" one.  Canopies have always been my major challenge...and I too, have never gotten myself motivated enough to tackle the vacuum method.

XP-80 is looking fine!  Smiley

Neal
  
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alfakilo
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Re: A New Challenge!
Reply #7 - May 30th, 2018 at 10:38pm
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Thanks to Neal for leading me on to this model. I got hooked on kitbashing plastic models in the 60s and this seems a natural extension of that.

I'm not going whole hog on this. For example, the Comet plan has the wing on the bottom of the fuselage whereas it actually was slightly above that. Not going to go that far.

I still have my Jetex motors from the 50s. Somewhere in all these years I lost the augmenter tube. Some other time. Maybe.

Not too sure about the canopy. Maybe it's time to make a home-built vac-u-form rig!
  
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Sky9pilot
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Re: A New Challenge!
Reply #6 - May 30th, 2018 at 9:51pm
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Outstanding...gotta do one of these too....too many planes, not enough time!!! Smiley
  

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alfakilo
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Re: A New Challenge!
Reply #5 - May 30th, 2018 at 7:48pm
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Here's the fuselage with XP-80 intakes mostly done and now working on the wing fillets. My plan is to do them in 1/32 sheet rather than paper.

  

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1_p80_b.jpg
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Sky9pilot
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Re: A New Challenge!
Reply #4 - May 29th, 2018 at 10:46am
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You're making great progress on this early jet!  I love it!  I'd be tempted to try to make a clear prop and make a pusher out of her, with the way the exhaust extends beyond the empennage.
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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alfakilo
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Re: A New Challenge!
Reply #3 - May 29th, 2018 at 9:45am
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This is the Comet side view modified to show the shortened fuselage and the revised contour of the XP-80 intake. I have added a former between #2 and #3 that is positioned to match the rear of the intake lip (not shown).
  

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p-80_plan_revision_aa.jpg
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alfakilo
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Re: A New Challenge!
Reply #2 - May 28th, 2018 at 12:57pm
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Thanks much! That was a good read with some excellent info in that Kalmbach 3-view. The fuselage formers answered many of the questions I had regarding the intake geometry.

I don't think I've ever tried swing flying. Looks like a simple way to have some fun!
  
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Sky9pilot
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Re: A New Challenge!
Reply #1 - May 28th, 2018 at 11:49am
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Alfa...you might be interested in Al's post here: Click Here Lulu Bell
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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alfakilo
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A New Challenge! XP-80
May 28th, 2018 at 9:44am
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Earlier in the P-59 thread, I mentioned starting a XP-80 build using an old Comet plan. I think this topic is better located here rather than the flying model area.

My goal is to build the XP-80 Lulu Belle as it currently looks in the National Air and Space Museum. Here is a link for that:

https://airandspace.si.edu/collection-objects/lockheed-xp-80-lulu-belle

The basic problem is that the XP-80 is smaller than the production model in the Comet plan. It's about 2' shorter and that makes the front end look different than is shown in the plan. Fortunately, I found some very good info that shows how this change was done. Now, all I have to do is to figure out how to change the model.

I've already begun building up the fuselage and must now 'chop' out a small section to reduce the fuselage length. The attachment shows how.

Should be fun!
« Last Edit: Jun 9th, 2018 at 9:25pm by Sky9pilot »  

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p-80_fuse_change.jpg
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