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Scratch Build 1400mm P-39

Hello FliteTest Forums, due to where I'm going to be living starting this summer, I can finally go to flite fest for the first time! And for it, I'll be building a 1400mm P-39 using dollar tree foam and balsa. The P-39 has always been one of my favorite WWII airplanes but there has never been a 1400mm EPO one on the market so I figured, why not build one? Right now I'm working on designing formers in SolidWorks and will hopefully laser cut parts in the following 2 weeks. As for construction techniques, I'm going to use the method that Ramy RC uses which is cutting up the foam into strips and planking it over the formers and then sanding them smooth to blend. Then I'll cover the foam with something like minwax and parchement paper. Also, if I have time, I'm planning on designing a 3D printed full scale cockpit for FPV purposes.

I'll probably end painting it in this scheme.
Made some formers yesterday for the full 3D model in SolidWorks. Drew them from the really great TopFlite kit plans. Next steps are the central support box, rudder, elevator, and making space for the full scale cockpit. Formers will be 1/8" plywood and will have weight saving cut outs once I finalize the fuselage supports.

I like your choice of plane. Question though, do you plan to mimic the p-39's unique engine placement by mounting an electric motor in the middle of the fuselage and then use a driveshaft to the front for prop drive?
Now that would be cool! Although I'd love to do that I'm planning on just putting the motor up front like normal.
Update on the CAD so far, I messed up. I did a bunch of work on parts last week but I did all that work in my school's CAD lab which has Solidworks 2018. My laptop has Solidworks 2017 so I can't open the files I did in the lab. I'm going to sort that out all next week and get all the assemblies up to the same version.


Well-known member
Ah college exams, I remember the days I was at college for engineering. I don't miss those days, glad I survived but I certainly don't miss the exams.

Good luck with your exams!
Well after a long run of nonstop exams and the problems I ran into with file compatibility, I've finally hit a nice little break. Today I made a bit of progress on the model. Tomorrow, I hope to finish the fuselage skeleton and move onto the control surfaces. Thank you all for being so patient.
After a very long hiatus it's time to start work on the P-39 again. I took a long break due to being super busy with school stuff but since I'm going on work rotation next semester, I'll finally have time to put the work in and finish it in time for this upcoming flite fest. However, I will be changing some things. Now that master series is a thing, I'm going to build this master series style from here on out. I'm simply amazed by what John Overstreet has done for building techniques this year and making building with dollar tree foam pretty much as good as depron in terms of scale and bending. We've come a long way since the first FT warbirds.
Made some progress on the P-39. Got most of the rear fuselage done as well as the vertical stab. Building it in its complete form and then turning parts into dwg's for lasercutting. I also plan to release the dwg's for free once I've refined and flown the plane along with the plans.

After a long hiatus of being too busy I've gotten back to work on the P-39. I've made the rest of the fuselage but still experimenting with the best lengths for each front piece to get the contours correct. CAD also can't simulate how foamboard works in real life so when I actually make a prototype, some stuff will probably change. I've also thrown a bit of wing in there just to visualize where I need to make cutouts (the hump below the bottom half of the wing is gonna go). More to come soon.

airacobra progress.png
Got more progress on the wing done, fillets to come next, those will be the hardest part for sure and then the canopy will be modeled. Once that's done, I'll prototype a belly lander for build purposes and then fly it when the weather here in the Midwest isn't garbage.