"Spiral lock out"

Jean Claude

Junior Member
Joined
Jan 2, 2009
Messages
2,589
Location
Centre FRANCE
Aircraft
I piloted gliders C800, Bijave, C 310, airplanes Piper J3 , PA 28, Jodel D117, DR 220, Cessna 150, C
Total Flight Time
About 500 h (FW + ultra light)
Does anyone have a credible explanation of the phenomenon "sipral lock out"?
thank you.
 
An explanation would be good.
Wot do you call a sipral lock out?
 
Could it be cyclic lock?:eek: In external loads a long line could swing to a point. that the weight of the load could be byond the helicopters c/g and all the cyclic input won't do a thing:twitch: and if the load is not pickled , both could spiral down .crunch.:rant:
 
Spiral locks, Dreadlocks?

Spiral locks, Dreadlocks?

I thought J.C. was asking about how we made dem long spiral curls stay set in our Jamacian Rastifarian dreadlocks!
Can't tell ya' dat, J.C., dat's a big secret! :D:D
 
Spiral lock out: Vertical descent flat with rapid rotation in yaw. Sometimes, no way out before impact.This was told to me many drivers here. They do not smoke grass!
 
I've never heard of that. Although it's true that most gyros will start an uncontrollable rotation around the vertical axis in a true vertical power off descent, this is easy to recover from by adding some throttle and applying opposite rudder or letting the nose drop to pick up some vertical speed. In either case: as soon as the rudder becomes effective again, you will be able to stop the rotation.

-- Chris.
 
Oh, that.
And no, they werent smoken any grass, it happens.
But its not an over control limit thing, its more to do with misperception.

One mistake sum make wen in a virtical decent is to allow the machine to enter a tail slide.
Too much backstick, with or without power on, and the machine will slide backwards.
The control surfaces now see reversed airflow, which produce percieved reversed reactions to inputs.
Rite rudder will make the nose yaw left, and rite stick, while induceing a slight roll rite, makes the machine appear to turn left [ coz your spirling backwards]. These reversed reactions to inputs confuse the crap outa people, and sum panic.
The unaware wont know they are slipn backwards till they experiance the reversed reactions, coz yaw strings, if you have one, is in turbulance and wont be seen to be leaning out, and most wont 'feel' it coz it dont take much backward slide to induce reaversed reactions.

I call it PIS. [ pilot induced spiral] ;)
 
Depends on how deep into the sh1t you allow the machine get Chris.
Its still recoverable, but not till you realise your go'n backwards.
 
Chris - > .....nose drop to pick up some vertical speed.

Chris If you really meant vertical could you briefly elaborate on why that would work, because if you had said *horizontal* speed it would have been obvious.
 
Chris If you really meant vertical could you briefly elaborate on why that would work, because if you had said *horizontal* speed it would have been obvious.

'tschuldigung, Jürgen, I did indeed mean horizontal.

Birdy, yes, a slightly backs sliding situation can indeed be confusing. When I got into one for the first time I pushed the throttle forward, which gave enough flow over the rudder to get me out of it. At this point -- heart a-thumping -- I hadn't realized what happened. But careless as I was back then, I went up real high and tried it again. Played around suffienetly long to learn enough about it but never really got to like it. In an MT03, getting the screw going fast enough is sufficient to give you good control in the correct direction of the rudder peddals. But pushing the nose forward will always do the trick.

-- Chris.
 
Are you guys talking about "flat spin"?

No, it is a vertical descent in which one is slightly sliding backwards. When this happens, the rudder inputs are reversed -- just like the steering wheel is when you are reversing.

-- Chris.
 
Perhaps an explanation for spiral lockout: Centrifugal Force combat thrust motor. Forward flight impossible. Just a drift around the axis of the spiral. Rudder unable to stop the yaw created by the "P factor". A numerical example below:
Jean Claude
 
Jean

Jean

If the yaw is produced by P factor why couldn't you just throttle back and nose down until it corrected itself?
Ben S
 
Ben, Nose down produces less thrust forward, and less centrifugal force is necessary. So, just reduced the radius of the spiral.
Throttle back reduces the "P factor" but also reduces the effectiveness of the rudder. Spiral still locked.
 
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Aah, the real Death Spiral then!!

1800fpm has got to hurt on impact.
 
Stick in any direction will unlock the spiral. [ forward will decrease the radius, back will increase it, rite stick will slow rotation and left stick will have you fly out of it.
Power change will also change radius.
The only control that COULD be ineffective is rudder, if its too small.
 
Birdy, You're certainly right, there is always an inclination of the disk that allows you to exit but it can be very important and discourage many pilots.
In my opinion the usual position of the disk or the throttle does nothing change. Both give a thrust vector which rotate with the airframe. Reverse orientation too frequent prevent to reach a sufficient forward speed. Or it vanishes at every turn, or it is weak and lateral (see drawing).

The only way out is to slow the rate of yaw. But if the wind of the propeller blows above the rudder too small, what to do? Jean-Claude
 
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Historically there have been many instances of aircraft that were designed in such a way that they could not recover from a spin, others that had difficulty in a flat spin. Generally the designers attempt to create machines that will. The same applies to gyros.

In many cases with the number of modified gyros or perhaps one-off's that are out there, it is logical to assume that there are some, that will not recover from certain maneuvers or situations when unlucky enough to stumble upon them.
 
As far as i can figure, the only time you can be 'locked' into any situation is if every control mode is on its limit.
Not sure too many people have been there. ;)
 
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