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FT Delta flat spin

Foamforce

Active member
#1
I have a FT Delta, my second build, and it sometimes gets into a flat spin. Generally it happens if I’m giving it too much input, possibly during a high climb stall. I’ve seen it four times now.

Is it possible to recover from a flat spin? When it happened yesterday I was very high, so I was able to try more throttle, cut the throttle, elevator, and aileron. Nothing seemed to affect it. On the bright side, I found that if I just cut throttle and let it fall, it fell as softly as a kite and was completely undamaged.
 

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Merv

Legendary member
#2
...Is it possible to recover from a flat spin?...
Yes, flat spins a generally easy to recover from. Let the all control surfaces return to neutral, the nose will drop, the air speed increase and the spin will stop. Then slowly pull out of the dive. In rare cases, you will need to input opposite rudder to stop the spin.

If you don’t want to flat spin or you want to lessen the spin, move the CG forward and or reduced the throws until the plane flys the way you want it to.

Flat spins can be a lot of fun, once you learn to control them. If you want to increase the spin, move the CG aft and or increasing the throws. The idea is to find the sweet spot, where you can start and stop one at will.
 

Foamforce

Active member
#3
Thanks! I’ll try decreasing the throws and moving the CG forward. I thought the CG was correct, but when I set all the controls to neutral, the nose never came down (during the flat spin). This plane doesn’t have a rudder, so that option is out.

Thanks for the advice!
 

Foamforce

Active member
#5
In a proper flat spin, the nose will never fall, that's kinda the point. Cg shift and full power if there's no rudder.
I’ll give that a shot!

Also, I found out that my Delta is overweight by about 60% (384g vs 238g). Factors include using Ross board, having a slightly larger motor (2208/14), adding a gyro, and 1/8” landing gear. The CG still works by putting the battery in the back, but what side effects would this have? I figure it probably needs to fly faster to get enough lift, which might explain why I find it so twitchy. Would it have other effects?

Thanks!
 

Piotrsko

Master member
#6
If the CG is in the proper location, does not matter much where the battery is. However, having said that, a rear most battery can cause the center of mass to be behind the cg which could make things squirrelly at low speeds like you experience. Move the cg forward just a bit and see if that fixes anything.
Heavy planes just need to fly faster that light planes and sink amazingly quick in landing configuration