Grumman AA1 yankee spin recovery?

Spinning an AA1 is a Very BAD IDEA...Here's why:

AA1 was originally a very innovative kit built aircraft (a la RV series) designed by Jim Bede as the BD-1.

One innovatinve component was the wing spar - an aluminum tube extending out to the end of the wing.

The ends of the tube are capped off and sealed creating a fuel tank.

In a spin, guess where the fuel goes?  ... centrfugal force forces the fuel  out to the end of the wing which

   a.  creates a counterweight that aggaravates the spin and worse...

   b.  could starve the engine for fuel so you would not have any power to stop the spin.

Another factor is that the AA! is very short coupled and the rudder may not be very effective to counter the spin as it accelerates .

Tell your friend that the AA1 is placarded "Spins Prohibited" for a very good reason (or two)

D

I flew a AA1 Yankee back in the early 70's when the issue of spin recovery first came up.  As I recall the problem was that the spin would flatten out rapidly and the only way out was to recover was to add power.  The problem was that the AA1's fuel is in the tubular main spar and if the spin flattened out the fuel would be forced out by centrifugal force interrupting fuel flow to the engine.  I also remember NASA doing some spin test in the Yankee.  They mounted a drag chute on the tail for flat spin recovery.  I don't know if they had to use it.

I owned a Yankee for 8 years. 

When I first bought it, it had a placard that said "No Spins".

That was good enough for me..

Perhaps that's one reason that I'm still here.

If a light aircraft is not readily recoverable from a spin, why did the FAA ever permit it to fly...much less be sold?

Some info on NASA's GA spin program is here.

NASA video showing deployment of the spin chute on the Grumman is here.

FAA AC-67C notes:

"Since airplanes certificated in the normal category have not been tested for more than a one turn or 3-second spin, their performance characteristics beyond these limits are unknown. This is the reason they are placarded against intentional spins. ....

The pilot of an airplane placarded against intentional spins should assume that the airplane may become uncontrollable in a spin."

More info in Rich Stowell's book "Stall/Spin Awareness".

I use to fly an AA-1 on fire patrol out VSF in Vermont. In  1975 there was a lot if talk about this and curiosity was said to kill

the Cat in my case along with a friend sought out the truth. We were bored with boring holes in the sky looking for smoke. After a short discussion as to the whys and why nots of putting such placard on a training aircraft. ( In a instant I wish we had discussed it ;longer.) I kicked into a spin entry and was in an heartbeat over on our backs entering the first turn looking at the upper wing skin wrinkling at the rib bond and went  quickly to recovery including a healthy blast of prop thrust long before she would have starved from un-ported fuel pickup. lesson learned. Not without test pilot's pay and a fast opening parachute.

Tim Stinson          

many people recommend heeding the NO SPINS placard, here's why:

http://oea.larc.nasa.gov/PAIS/Concept2Reality/spin_technology.html

"Langley’s chief test pilot, James Patton during flight test program.
Note symbols denoting successful operations of spin-recovery parachute system."

NEVER !!  There was a sobering video back in the 70s, taken from the cockpit of a test Grumman American (later Gulfstream) AA series aircraft. After one turn, the spin went flat and the engine failed due to the reasons cited above. A drogue chute was deployed but it took an unusual number of turns before the airplane destabilized enough to effect a recovery. I'm probing the foggy corners of my brain now but, as best I can recall, the test pilot was quite emphatic about staying away from conditions that might precipitate a spin in these airplanes.