OV10's version of Foam 72" (1800mm) OV-10A Bronco build

[Twowingtj]

Looking good Charlie! Good choice for gear. There are a lot of challenges with doing a scratch build. The end result can be very rewarding for sure.

[OV10]

Twowingtj Thanx Tony Had to go with the YAK gear because it is the closest looking to the Bronco gear profile and least expensive.
Speaking of challenges, one of the things I discovered during this build I believe is the reason the other pilots are commenting on seeing a "wagging" on the Flight Line Bronco due to a structural anomaly in the wing/boom connection rigidity.
When I was doing the fit up of the center wing/booms/fuselage I lifted the assembly by one of the booms at the rear and observed that there was torsion on the wing between the fuse/boom.
So I alternately lifted the booms and could observe a cross torsion which would tilt the vertical pitch of the prop drive lines at the leading edge of the wing
OK...….had to add another CF spar (that's 3 now) in the center wing with a new one at the leading edge cause the quarter round balsa leading edge was a 2 piece segment between the boom/fuse and not giving full span rigidity.
I assumed that the horizontal stab would tame this down a bit also but since I do have the FL Bronco to examine I did the same test on it.
To my surprise there is some torsion on the center wing between the fuselage/boom when lifted by the rear of the boom.
I am convinced that this is the reason for the "wag" when the airframe is subjected to really heavy maneuvers or winds and is countered real time with the gyros.
As has been commented by some others across the forum platforms that this seems to prevalent with all sizes of the Bronco model.
I will admit that I never saw any of this on my Uravitch 52" version.
It wouldn't surprise me if the full size showed some hints of this trait in hard maneuvers
So it wags in the air sometimes...…….it is still the best darn ground poundin airframe for rough terrain landings

[Grossman56]

Looks great CB!! You'll soon have the best of both worlds!!

Grossman56

[Pauly]

Very Nice. You'll be in the air in no time.