Foamboard SAAB JAS-39 Gripen EDF (images, plans, build)

[Bayboos]

I can't say I did a proper experiment; but I did have cheater holes (by accident, more than anything else) on my Gripen before the first crash. I did not notice any significant difference after rebuilding it without the holes.

 

[cosmocop]

Good morning and happy holidays! I just wanted to chime in again and report that I'm now working on an 80mm version of this. I plan to run a 5000mah 6S. I just finished cutting out the parts. I ended up retiring my 70MM version early this year.

I plan on leaving the paper on both sides of the foamboard this time (except for maybe a couple of areas). I'm a little concerned with the how the single layer DTFB wings will hold up to the weight. I'd like to do an airfoil (fold over style or KF) and will probably run a carbon rod (or a couple) as well.

Has anyone made a larger version of this (80MM+)?

 

[cosmocop]

Good afternoon. I just wanted to report back on this and say I did just finish building an 80mm version of this and did a maiden flight this past weekend. It did great!

I used a Freewing 80mm inrunner (1900 KV) with a 5000 mah 6s lipo. The wing loading was a little higher than I would have liked but it had plenty of power. The sweet spot would probably be a 4000 mah as I only used 22% of the 5000 mah after 2:20.

I kept the paper on the foam this time but I still think it would have probably been a good idea to double up the foam on the vertical and wings. The wings had a carbon rod but no airfoil (outboard leading edge slats were glued down, however). Canards were activated and definitely helped the pitch authority. If I build another one I think I will make the elevons a little bigger also (maybe add 1/2").

Looked great in the air! Excellent design.