Just took the ASF Spatial Disorientation seminar, which was very good. Got into a discussion about graveyard (JFK Jr.) spiral.
Got into a discussion with my friend about the different symptoms and resolution of a spin versus a spiral. My take is that on a spiral airspeed would be very fast, whereas on a spin it would likely be slow and the plane would be in a stall. I’d also think that with a spiral you would use ailerons to level the plane, whereas with a spin you would use rudder.
However, AOPA’s December “Never Again” (on web site) pilot talks about spin with what I would think to be spiral symptons. He used rudder to recover and lived to share his experience. Presumably, AOPA editors review these articles for correct input. Looked at Cirrus POH, and they talk about “spin/spiral,” and suggest using rudder.
This could well be one of the multitude of cases where I thought I knew it all and maybe didn’t.
In a spin, since both wings are stalled, I would expect the stall warning to sound. In either a spin or a spiral the first actions should be power to idle and neutralize the aileron. I never tired it but the rudder would probably reduce the turn rate in a spiral as well as a spin. According to the Cirrus POH the recovery for a spin is the parachute which should also work for a spiral.
Since an airplane continues to accelerate in a spiral wouldn’t there be a danger of substantially exceeding the max CAPS deployment speed of 130 kias? (quoting only my memory here, not the POH). I believe Art’s first two remedies (pull the power, level the wings) should do the job if you’re not too far beyond Vne.
Mike said:
Since an airplane continues to accelerate in a spiral wouldn’t there be a danger of substantially exceeding the max CAPS deployment speed of 130 kias?
I say:
Who cares about the 133kts. If I have had a catastrophic failure in the airframe and the speed was in excess of the 133kts. guess what? I’m pulling the chute!
Don’t think leveling the wings is an option you can count on in a spin, due to stall and pissible loss of aileron authority. Therefore, rudder is the recommended course of action in a spin.
However, in a spiral, ailerons would have authority, so presumable either rudder or ailerons could be used. Conventional wisdom is to use ailerons to level wings in a spiral, yet CD POH recommends rudder for “spiral/spin” as though they’re the same. That’s the part that I’m having trouble reconciling.
There is an excellent on the spiral on AvWeb.com. The gist of the article is “step on the sky”, that is, left spiral, right rudder. Due to differential wing lift, the wings are levelled with minimum of stress, and the plane will pull itself out of the dive due to increase lifting efficiency. I tried this intentionally in a VERY early spiral, well under Vne, and it really is quite impressive. The link for the article is http://www.avweb.com/articles/spiral/index.html
Perhaps it will help. It certainly answered many questions for me.
To me a spiral is just a fully developed spin that’s not flat. Others may have a different definition. Definition isn’t important because recovery is the same. The first thought should be full opposite rudder! Then pull the throttle and neutralize the ailerons.
These 3 steps can be accomplished so close to simultaneously that the order is not important but the thought process is. When that wing drops so rapidly the instinct is to correct with aileron but that only exacerbates the problem by adding drag to the very wing we want to lift. Precious seconds can be lost while the brain is doing a memory search to come up with the rudder solution. Push and hold the rudder. Make it sudden, push to the stop and hold it until the spinning stops.
Now you are in a straight dive. Recover to level and just let the excess speed bleed off.
The “step on the sky” is for upset. It doesn’t work so well for spins where all you may see is ground.
To me a spiral is just a fully developed spin that’s not flat.
Unfortunately that’s completely wrong - in a spiral dive, the aircraft is not stalled, and airspeed is increasing rapidly. In a spin, one wing is stalled (the other is not) and airspeed is relatively low and stable. Recovery in a spin requires that the stalled wing be unstalled, which invariably requires stopping the rotation and may require down elevator. Recovery from a spiral dive is accomplished only by levelling the wings, then pulling out of the (now wings-level) dive.
Many aircraft will recover from a spin if you just take your hands off the controls. A spiral dive always requires the pilot to make inputs to recover. That, and the increasing airspeed that leads to structural failure, are the reasons that the spiral dive is such a killer, even at altitude. Spins usually lead to accidents only at low altitudes.
Having said all that, just using rudder may be enough to level the wings in a spiral dive, but I wouldn’t rely solely on it.
This is why the FAA position is usually good only for reference, and provides no substitute for real world spin training and actually trying to use the ailerons in a spin to find just how bad a thing this is to do. Clyde has provided the classic, correct definition of a spin as being a condition in which one wing is stalled and the other is not. Trying to use the ailerons at all will only prolong or make recovery impossible. Most pilots untrained in spins will try to pick up the low, stalled wing with the ailerons making matters much worse. Keep in mind that stall is a function of angle of attack and when you pull the stick over to the high side towards the flying wing, the aileron on the stalled wing goes down. Draw a line from the trailing edge of the aileron to the leading edge of the wing to see your new chord line and the new, much higher angle of attack. Don’t expect the up aileron on the other wing to pull you out of it, it is just parked up in a layer of turbulent air and it’s effectiveness is minimal. So, if you want out of a spin, step hard on the rudder toward the outside of the rotation, nudge the stick forward to break the stall and center the rudder when the rotation stops, right away. If you hold it too long you will go into a secondary spin in the other direction because you will be in a low airspeed, high angle of attack condition when the rotation stops.
The FAA makes decent reference material for a lot of things, but if you want to learn about recovering from spins, get instruction in a plane certificated for it from a cool headed instructor. The entry to a spin can be quite disorienting and descriptions don’t do it justice to an inexperienced pilot. Trying to understand how to recover from one by reading about it just not going to work. Imagine if you had to land an airplane the first time just by reading about it.
Humble opinion…
Greg
This is why the FAA position is usually good only for reference, and provides no substitute for real world spin training and actually trying to use the ailerons in a spin to find just how bad a thing this is to do. Clyde has provided the classic, correct definition of a spin as being a condition in which one wing is stalled and the other is not.
I have 2 comments to this.
First of all I (and the FAA) have said about ailerons is that they should be neutralized. I have never read any spin recovery procedure that did not call for neutralizing the ailerons. Neutralizing the ailerons is not the same thing as trying to use them for recovery.
Please give me a reference for the the “classic definition” of a spin as one wing stalled and the other not.
Art,
Responding to your two comments, I read your comment regarding the ailerons still having effect as implying they should be used in a spin recovery. Gladly we agree that is not correct. In your previous post ‘way up there’ you did say that, apologies for misunderstanding your subsequent post.
If you are interested in definitions of spins, you could take a look at Aerobatics Today by Bob O’Dell. He gives an excellent description of exactly what happens in all common aerobatic manuvers, not just a blow by blow of how to perform them like most aerobatics books. His discussion of spins is particularly enlightening, as he provides a detailed description of diferences of angle of attack between the two wings and how this creates the state of autorotation. In order for autorotation to develop, one wing must be producing lift while the other one isn’t, or the plane doesn’t autorotate. You will find it on Page 72.
Another great description is contained in the book Sailplane Aerobatics by Les Horvath. On page 30, Les describes various spins, their causes, and the effects of aft CG, trim settings, and size of control surfaces of the aircraft. I think I have more books on the subject, but they are probably up in the attic. Hope this helps in your research.
Greg