Sailplanes Aerobird Swift, and the "Death Spiral"

EyeStation

Well-Known Member
Beachy and I were out at our local field today and I brought the Aerobird Swift out of the closet and powered up that long antenna/ 8 AA cell transmitter. The wind was a nice 5-8 mph with gusts up to 12 mph.
I got the plane up with the servo horns out on their outer most holes. Seemed responsive, but the V wing elevator was a challenge to pull up on throw into the wind on takeoff.
So we adjusted the ailerons and V-Tail horns up two holes.
Beachy took it up and was having a blast, soaring and powered stunts, then an unexpected Death Spiral to the ground which he was unable to correct out of. Took the walk out and found the bird without a nose, but relatively unscathed. We wrote it off to the rate being on the Hi setting and Beachy not being in that situation before, and really felt helpless once the spiral started.
So, we lowered the rate to the Lo setting and I took it up for a flight. I was taking a more leisurely flight when I did an aileron turn out of the wind and watched the nose drop and plane start to spiral down.

What causes these uncontrollable spirals? Is there a way to pull out of one of these predicaments?

I do have to say, that Aerobird Swift is a tough little plane considering all this baby has seen and is still not done flying yet.
 

Chris O'Hara

Thermal Padawan
Not sure this is the right place for this thread, which might be the reason no one has responded. I would put this in the propeller plane section. As to getting out of a sticky situation like that, what exactly did you try? I have flown all types of planes and with enough altitude one can recover from pretty much everything. I have flown one of the older Aerobird planes by Horizon (years ago) and experienced something like what you described, where the plane turned hard and entered a spiral. I was not able to recover from it and the plane went into the ground. Because of the nature of the design, it cannot handle certain attitudes as well as a traditional high wing plane. Also, the fact that they are a bit under powered means that they stall easier when climbing, causing loss of control until airspeed speed is gained again

The moral of the story may be keep it high and give room for recovery. I can (reluctantly) tell you I know this all too well from experience. Hopefully that helped some.
 

pvolcko

Well-Known Member
My guesses.

It may be stalling (hard to know from the description you gave). In that case you need to fly the nose down and regain speed, then gently pull out to normal flight attitude again. Do not keep trying to fight it all the way down because it will not recover. You need to give in to the stall, regain forward airspeed over the wing, and then pull out gently.

When this happens, if it is tipping to one side or the other, then that indicates a "tip" stall where air over one wing gave out more than the other and it causes it to turn and fall, in a spiral. Again, hope it happens with enough altitude, fly into the stall. Gently apply ail to counter the spin. Then once airspeed is up and spin corrected, pull up.

If it flat spins... tough to recover sometimes, especially if it is tail heavy and the tail falls first. If possible recognize it quickly and apply elevator and ail to try to dive into and turn into the direction of the spin. Get the nose down, then correct spin with ail and pull out as before.
 

EyeStation

Well-Known Member
Thanks guys. And yes Pvolcko, I believe the tip stall best describes our incident. I think both of our responses at the time was to elevator up. But the V-Tail is not that commanding when in this position. I will have to remember the two points, regain air speed, and counter aileron.
 

pvolcko

Well-Known Member
Yeah, if you immediately elevator up it will tend to remain in the stall condition, always trying to pull out of it and not having enough airspeed to do so. Especially if it is spinning at the same time, the elevator only will probably only lead to a more violent spin and wing turbulence. Stable out the spin, let it dive a bit, and then elevator out.
 
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