Gyro's in flat spin

[Bob]

Howdy all !
In a discussion on the ASRA site I ran accross what was a new thing to me , Gyros going into a flat spin.
I never hurd of that before , the fellers said that under certain curcumstances a gyro can and will gointo a flat spin.... alot of the gyros can just power out of it and a few cannot.

I would like to know more of this ability of the gyro.
anyone know of any instinces that this has occured ?
....
the consencis seamed to be a steep low power desent can initiate the spin in some cases.... rudder control is Minimal in most cases
and the spin quite fast.... applying power seamed the only way to gain control again as the gyro slowly widens the spin as it desends till if finally brakes free and flys away....
the lack of rudder control appairantly is due to the Horizonal stablizer being at or near the frame in most cases... and the rudder is then emersed in stalled air rendering it practially useless.... some have switched to the T tail configuration to help prevent this, where in theory the HS is above the rudder and the rudder has undisturbed air to deal with. sounds quite logical to me ...
Also in most cases the tail section is a Close coupled one, meaning very close to the prop giving the rudder a short moment arm to counter act the spin.
Is the T tail the only way to go ? Or could sadisfactory control be obtained with a HS on the frame ? or an HS in the prop wash just off the frame ?
This could no doubt be a serious problem if a person incountered a flat spin and didn't know what to do about it !
.... No doubt it could be a serious problem even if you DID know what to do ! ...

Any Ideas or comments ?

C ya !
Bob....

[pwendell]

http://www.rotaryforum.com/forum/showthread.php?t=5213&highlight=flat+spin

[Douglas Riley]

To summarize:

1. Gyros don't "flat spin" in the sense that FW planes do. FW flat spins are the result of the specific behavior of fixed wings, which we don't have.

2. A given gyro design may have insufficient vertical tail power to prevent some form of rotation in a vertical descent. Certainly the rudder gets less effective at low airspeeds and power settings on all gyros. The good and proven designs, however, retain enough rudder power to prevent loss of control, even at zero airspeed.

3. Application of power is probably the best way to recover from an unintentional vertical spin. It will enhance the airflow over the rudder and thereby increase its power.

4. There have been a few cases in which an experimental design locked itself into a spin and wouldn't readily come out. Large vertical surface area ahead of the CG is often to blame. A short, stubby vertical fin with a large HS under it could be blanketed in a vertical descent; a tall vertical is less likely to have this problem, as is a vertical whose HS is mounted partway up the vertical. The latter location is a better one for the HS, anyway, in most cases.

[Friendly]

Doug, would the winglets like on the Magni and Larry Martins Ultra Stabb for the RAF be effective against this??

[MichaelBurton]

The gyro spin flat or otherwise is just a spiraling descent. The problem is that in a true zero airspeed descent and a fast "spin" rate you will need power to arest the "spin". BTDT. As soon as power is added the gyro responds quickly. The other problem you could have is that the rudder may take a bit more force than normal to come back to center.

lol

[Doug Riley]

Mark -- It's hard to say in general if winglets will be a cure if the gyro has yaw problems. In a true vertical descent, they will be in air that's already been disturbed by the HS that is "upstream" of them and (presumably) stalled. In a fast spin, they may also be blanketed by the main rudder. I would expect that making the main rudder taller and/or moving the HS partway up the vertical fin would be more effective.

[OzyRuss]

[QUOTE=MichaelBurton]The gyro spin flat or otherwise is just a spiraling descent. The problem is that in a true zero airspeed descent and a fast "spin" rate you will need power to arest the "spin". BTDT. As soon as power is added the gyro responds quickly. The other problem you could have is that the rudder may take a bit more force than normal to come back to center.

lol

Sorry micheal, a spin is not the same as a spiral......when the gyro is literally spinning like a top, and reeeel fast also, you wish you were not there. the pilot that actually got caught here, I know. He was dead lucky he had about 2 thou to play with. He tried different ways to arrest, to regain control, the only thing that worked was a heap of power, lower nose. He shyte himself.
I said did you try to turn the spin into a spiral, and get out that way, yes he said, didn't work. What realy alarmed him was the suddenness of the spin, and the rotating speed, which he said was FAST.

I don't know the whys,etc, but his machine is real short coupled at the rear, and a bloody SMALL tail area, this includes the stabaliser, I feel this is possibly the problem.....????????

[C. Beaty]

Flying devices, from birds to blimps, that depend upon prop blast over the tail to maintain weathercock stability ought not be flown.

Has nothing to do with gyros in particular.

[mceagle]

Hear hear.

Any gyro should be able to maintain good yaw stability in all conditions, including engine out.

I think the original question relates to the case of an normally "yaw stable" machine that enters an unrecoverable flat spin - ie. it is rotating about its C of G. (usually the result of a powered nose high vertical descent gone wrong).
Two things worth noting here is that it didn't seem to happen with short coupled 'Bensen' style machines, and that it almost exclusivly happens to machines with larger diameter propellers and a horizontal stab under the rudder.
Presumably the larger prop with vertical airflow supplies the rotational force and the blanketed rudder hinders the correction.