Misconceptions with stall/spin
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Misconceptions with stall/spin
How many of you teach your students only to use the rudders in a stall? Or not to use Ailerons in a Stall?
I've had quite a few students that haven't been mine tell me that their instructors told them "just use the rudders to keep the plane level with the horizon". I dont' think many of them noticed that the ball in the inclonometer was fully deflected!! with a Spin situation.
There are also a few misconceptions about using ailerons in a stall. You can use them as long as you keep the plane co-ordinated...so basically very small imputs and corrections.
Back to basics..two things needed for a spin....a stall and unco-ordinated flight. Once you stay co-ordinated you could be at 90 degrees bank...you will not spin.
Any suggestions?
I've had quite a few students that haven't been mine tell me that their instructors told them "just use the rudders to keep the plane level with the horizon". I dont' think many of them noticed that the ball in the inclonometer was fully deflected!! with a Spin situation.
There are also a few misconceptions about using ailerons in a stall. You can use them as long as you keep the plane co-ordinated...so basically very small imputs and corrections.
Back to basics..two things needed for a spin....a stall and unco-ordinated flight. Once you stay co-ordinated you could be at 90 degrees bank...you will not spin.
Any suggestions?
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Aproaching the stall you are right and in most modern aircraft you will be ok using rudder/aileron in the stall, but teaching SHOULD be - approaching the stall keep the aircraft in balance with rudder and control roll with aileron - IN the stall, Ailerons central and PREVENT FURTHER WING DROP with rudder (you DO NOT roll the wings level UNTIL you have recovered from the stall). To say you will not spin if you stay coordinated is NOT correct, MOST modern machines won't but I have ended up in a spin from a barrel roll with the ball inthe center in one machine at over 90kts ( 1G stall 42kts),putting the aileron in to stop the roll causing the inboard wing to stall!
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Using the rudder to prevent further yaw works in all aircraft. Using the ailerons might work in some. Try using the ailerons in a Tomahawk. When you get a wing drop in a stall you are in the beginning of a spin. If you use spin recovery technique it works every time. In a c 152 the ailerons work in the correct sense throughout a stall, but the POH still advises "place ailerons in neutral and use full opposite rudder...............Cochise, what aircraft do you fly?
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Indeed. misconceptions.....
Spin = Stall + Yaw
It does not matter HOW the yaw got there.....Is it possible to spin from coordinated flight in a stall - of course it is - all you need is a wing drop - dont forget air (due to its nature) does not produce an identical symmetrical flow across both wings - it is chaotic across both wings - especially in the stall...
Yes I teach people to not use ailerons - why is explained. Why they can be used in slow flight prior to the stall is covered in ex 10a - if the student doesnt understand that by 10b then 10a wasnt done properly. Using ailerons causes increases in AoA. Therefore it doesnt matter *how* big the deflection is, what matters is the AoA..therefore even a small use of ailerons on some aircraft can cause either a deeper stall - and likely wing drop - thus causing yaw (secondary affect of roll...) or you may be flying an aircraft with adverse aileron yaw - which at slow speeds will lead to larger inputs of rudder...
As for rudders - I teach - rudder to STOP yaw. Not to pick the wing up....
Just my thoughts - albeit a little chaotic
Let us not forget that that the purpose of teaching is not to cover ALL situations on ALL aircraft types. But to equip people with the necessary skills and knowledge they need to safely fly on the wide variety of types.
Each individual should obviously make themselves fully aware of the stall/spin characteristics of the aircraft they actually fly...it is our job as instructors to make sure that they understand that.
Spin = Stall + Yaw
It does not matter HOW the yaw got there.....Is it possible to spin from coordinated flight in a stall - of course it is - all you need is a wing drop - dont forget air (due to its nature) does not produce an identical symmetrical flow across both wings - it is chaotic across both wings - especially in the stall...
Yes I teach people to not use ailerons - why is explained. Why they can be used in slow flight prior to the stall is covered in ex 10a - if the student doesnt understand that by 10b then 10a wasnt done properly. Using ailerons causes increases in AoA. Therefore it doesnt matter *how* big the deflection is, what matters is the AoA..therefore even a small use of ailerons on some aircraft can cause either a deeper stall - and likely wing drop - thus causing yaw (secondary affect of roll...) or you may be flying an aircraft with adverse aileron yaw - which at slow speeds will lead to larger inputs of rudder...
As for rudders - I teach - rudder to STOP yaw. Not to pick the wing up....
Just my thoughts - albeit a little chaotic
Let us not forget that that the purpose of teaching is not to cover ALL situations on ALL aircraft types. But to equip people with the necessary skills and knowledge they need to safely fly on the wide variety of types.
Each individual should obviously make themselves fully aware of the stall/spin characteristics of the aircraft they actually fly...it is our job as instructors to make sure that they understand that.
Moderator
I had an instructor who came to work for me, and had been taught to teach "full opposite rudder" in a wing drop fair enough in a fully developed spin, but my theory is that if you have a wing drop, the use of rudder is not as important as reducing the angle of attack and recovering from the stall. It's only us that like to have wings level, the aeroplane doesn't know or care where the horizon is. So I teach, lower the nose by putting the hand in the middle of the control column to avoid the temptation to use aileron, then when speed is coming back, level the wings with aileron and regain balance with rudder.
fair enough in a fully developed spin, but my theory is that if you have a wing drop, the use of rudder is not as important as reducing the angle of attack and recovering from the stall. It's only us that like to have wings level, the aeroplane doesn't know or care where the horizon is. So I teach, lower the nose by putting the hand in the middle of the control column to avoid the temptation to use aileron, then when speed is coming back, level the wings with aileron and regain balance with rudder.
I taught stall recoveries as:
Centralise aileron
Rudder to stop *further* yaw (NOT raise the wing NOR prevent further wing drop)
Reduce AoA eg to ~ glide attitude
Add power
Level the wings after regaining normal flight
Recover from the dive if necessary.
If yaw can't be stopped then to use spin recovery ie power off & ailerons neutral
full opp. rudder
continue pitch ND until stall exit
neutral rudder after rotation stops, then
standard spiral dive recovery.
Centralise aileron
Rudder to stop *further* yaw (NOT raise the wing NOR prevent further wing drop)
Reduce AoA eg to ~ glide attitude
Add power
Level the wings after regaining normal flight
Recover from the dive if necessary.
If yaw can't be stopped then to use spin recovery ie power off & ailerons neutral
full opp. rudder
continue pitch ND until stall exit
neutral rudder after rotation stops, then
standard spiral dive recovery.
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I suppose it has alot to do with the Aircraft you teach in. Today I had a student nearly spin me at less than 2000'...I was not impressed but I"m glad it nearly happend because it brought the problem to my attention.
I don't teach them to use the ailerons in the recovery...I mean before the stall....even before the buffet.
As I said every aircraft is different, the 172 is harder to spin as is the 152 (A good thing me thinks!!)
I did my spin/upset/aerobatic training in the Zlin...Czec made...very nice and it has the trait that you won't spin if you're co-ordinated. I could understand in heavy updrafts the relative wind may change and cause the AOA on each wing to change resulting in a spin. I've always stuck to the concept that a spin needs 2 things
1)Stall
2)unco-ordinated flight
if you don't have both you won't spin. But that's not to say that you're rudder trim tab could be off and your Turn co-ordinated not calibrated properly then I agree...you will spin, but as far as the theory goes I tend to stick close to that.
There is one major thing I've learned with aviation though..............As soon as you say never it'll bite you in the A$$!!
cheers fellas
I don't teach them to use the ailerons in the recovery...I mean before the stall....even before the buffet.
As I said every aircraft is different, the 172 is harder to spin as is the 152 (A good thing me thinks!!)
I did my spin/upset/aerobatic training in the Zlin...Czec made...very nice and it has the trait that you won't spin if you're co-ordinated. I could understand in heavy updrafts the relative wind may change and cause the AOA on each wing to change resulting in a spin. I've always stuck to the concept that a spin needs 2 things
1)Stall
2)unco-ordinated flight
if you don't have both you won't spin. But that's not to say that you're rudder trim tab could be off and your Turn co-ordinated not calibrated properly then I agree...you will spin, but as far as the theory goes I tend to stick close to that.
There is one major thing I've learned with aviation though..............As soon as you say never it'll bite you in the A$$!!
cheers fellas
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Hmm, so even if you tried you couldn't spin the plane from a climbing or descending turn? Theoretically, you have yaw, and uneven a of a between the 2 wings, which should result in a wing drop, possibly stall if the conditions are right. Then again, a c 172 should theoretically stall with full rudder and control column full back, but we've all had those days when we just can't get a good spin in that one direction!!!
damn self-recovering airplanes!!
CFI: I don't know about you, but during a stall is one of the times when I would strongly advice against letting go of the control column to scratch your nose, tune a radio, or shift your hand position on the yoke!! Just my opinion, but shouldn't the student be trained to keep their hand where it is, and simply learn to resist the gut reaction to roll level with aileron. Training them to move the hand to the center of the yoke seems like it's teaching the wrong reaction. Besides, in many stalls, the recovery happens so fast that lifting the low wing can be initiated within seconds, and I kind of like to have aileron control when my airspeed begins to pick up.
And just a quick question to anyone listening: ever experiment with using opposite aileron to lift the stalled wing? or opp. aileron in a fully developed spin??
damn self-recovering airplanes!!
CFI: I don't know about you, but during a stall is one of the times when I would strongly advice against letting go of the control column to scratch your nose, tune a radio, or shift your hand position on the yoke!! Just my opinion, but shouldn't the student be trained to keep their hand where it is, and simply learn to resist the gut reaction to roll level with aileron. Training them to move the hand to the center of the yoke seems like it's teaching the wrong reaction. Besides, in many stalls, the recovery happens so fast that lifting the low wing can be initiated within seconds, and I kind of like to have aileron control when my airspeed begins to pick up.
And just a quick question to anyone listening: ever experiment with using opposite aileron to lift the stalled wing? or opp. aileron in a fully developed spin??
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You're absolutely right that they should keep their hands where they we're entering the stall, I was talking about before entering the stall.
As for your question about using the aileron in a spin, when your wings are stalled you have that mushy sensation in the control colum..no? That's because they are no longer as effective. Remember in a spin one wing is more stalled than the other so by adding opposite aileron all you are doing is increasing the AOA on the "more" stalled wing. Hence worsening the situation.
I teach that students can use small amounts of aileron correction before they reach the pitch up phase of the stall, once they get there I just get them to make sure the plane is kept co-ordinated during the phase where they keep maintaining the pitch while they're increasing the back pressure.
An important thing to remember in the recovery is that when you've added full power you're going to receive a hell of alot of Torque thus you'll need quite a bit of right rudder correction (for a right hand prop)
As for your question about using the aileron in a spin, when your wings are stalled you have that mushy sensation in the control colum..no? That's because they are no longer as effective. Remember in a spin one wing is more stalled than the other so by adding opposite aileron all you are doing is increasing the AOA on the "more" stalled wing. Hence worsening the situation.
I teach that students can use small amounts of aileron correction before they reach the pitch up phase of the stall, once they get there I just get them to make sure the plane is kept co-ordinated during the phase where they keep maintaining the pitch while they're increasing the back pressure.
An important thing to remember in the recovery is that when you've added full power you're going to receive a hell of alot of Torque thus you'll need quite a bit of right rudder correction (for a right hand prop)
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OOPS, what I meant to ask was if anyone has experimented with aileron INTO the spin to aid in recovery. It could be an interesting sensation. Use this in stalls when you get a wing drop, turn the control column towards the falling wing and see if it helps bring the wing back up, or arrest its descent. It should work in theory.
I haven't experimented with this yet, but it's on the agenda for the next flight.
I haven't experimented with this yet, but it's on the agenda for the next flight.
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I have found that teaching the stude to use rudder at the stall to 'limit further wingdrop' can actually lead to 'EXCESSIVE AND OVER ENTHUSIASTIC' opposite rudder.......leading to SPIN!
I simply teach the stude to lower the nose gently to unstall (OK, stick to centre then forward), full power to accelerate, then when the a/c is flying again to use ailerons and rudder in normal fashion.
Why make it such a black art? Keep it simple I say
JWF
I simply teach the stude to lower the nose gently to unstall (OK, stick to centre then forward), full power to accelerate, then when the a/c is flying again to use ailerons and rudder in normal fashion.
Why make it such a black art? Keep it simple I say
JWF
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bcpilot -
The Cessnas & Piper trainers I have flown seem to be quite tolerant of aileron use right down to power off 1g stalling speeds, I assume at least partly because of the washout in the wings (causing the wing root to reach critical AoA first, leaving the aileron bit unstalled.) Also differential ailerons help... So left aileron will always cause left roll, and right aileron right roll provided power is below cruise settings. At least that is the case in my experience.
The Robin 2160, with no washout or differential aileron gearing, does allow a nice demonstration of aileron stall at high AoA, but even full aileron use in the stall just arrests further roll and enhances buffet. It does not seem to cause adverse roll much, provided of course one is reasonably in balance.
Never tried pro-spin aileron. I think you would just enter a spiral dive with possibility of aileron roll.
Most controllable aircraft I ever flew was the two-wing (fore & aft not one above the other) Eagle 150. Stick fully aft and the aircraft descends nicely, slightly nose-high, with full aileron authority!
cheers,
O8
The Cessnas & Piper trainers I have flown seem to be quite tolerant of aileron use right down to power off 1g stalling speeds, I assume at least partly because of the washout in the wings (causing the wing root to reach critical AoA first, leaving the aileron bit unstalled.) Also differential ailerons help... So left aileron will always cause left roll, and right aileron right roll provided power is below cruise settings. At least that is the case in my experience.
The Robin 2160, with no washout or differential aileron gearing, does allow a nice demonstration of aileron stall at high AoA, but even full aileron use in the stall just arrests further roll and enhances buffet. It does not seem to cause adverse roll much, provided of course one is reasonably in balance.
Never tried pro-spin aileron. I think you would just enter a spiral dive with possibility of aileron roll.
Most controllable aircraft I ever flew was the two-wing (fore & aft not one above the other) Eagle 150. Stick fully aft and the aircraft descends nicely, slightly nose-high, with full aileron authority!
cheers,
O8
