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Flight dynamics - stall management controversy...

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Hi,A couple of days ago, a few pilots and flight instructors got into an informal debate at the local FBO (LLMG)...Some argued that upon entering a stall, you shouldn't touch the ailerons until fully recovered, the other group stated that since the wing roots generally stall first you'd still have enough aileron authority without risking aggravating the stall into a spin...Now...I am a bit confused about this topic...I know that the wing roots stall first but was always told during my training to refrain from touching the ailerons during a stall...I'd like to hear your opinions on that...Twister

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My opinion as an expert 172 pilot (3.7 hours :) ) is that you would want to stall with your wings as level as possible, hopefully avoiding a spin.Although, if you use the ailerons to try and level out, you would effectively be increasing the angle of attack of the low wing, possibly increasing the chance of a spin.It seems to me that you're darned if you do, and darned if you don't. :(

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One other thing to bear in mind is the effect of adverse yaw. If you try to use ailerons to raise a dropped wing appraoaching the stall, you'll see the nose start to slice quite dramatically to the side because of adverse yaw, making the task of holding heading through recovery that much harder.Paul

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Depending upon the scenario, I would probably be more interested in recovering from the stall than leveling the wings. In most light trainers, as soon as you relieve back pressure then you're flying again and can safely add aileron input. We do this all the time in the training environment (and while landing); it's called "slow flight". Modern trainers (most Pipers/Cessnas made since the '70's) can be flown with the stall horn screaming at you can still use full control inputs without inducing a spin. Typically, these aircraft just mush along in a stall anyway (assuming power off). To induce a spin in a 152/172 you really need to accelerate the stall with an abrupt (and somewhat prolonged) pitch up before the occurrence of stall at the root. You then need to hold full aft yoke for the aircraft to remain in the spin. Older aircraft with a more symmetrical leading edge do not have the same docile stall characteristics. This is also true for many modern high performance light aircraft. Bottom line: know your airplane and train, train, train.To answer your original question, if the aircraft is still in a stall and (for whatever reason) you need to make bank correction then the rudder is the instrument of choice.

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In some newer airplanes, i.e. the Katana, (and some older ones), the ailerons remain fully functional throughout a stall. In others, aileron input will be completely ineffective, i.e. C152, C172, and will do nothing to lift a dropped wing (which is what puts you into a spin, not using the aileron). Using the rudder to lift a dropped wing works no matter what, so it would seem that using the rudder is the safest thing to do if you want to avoid a spin. Of course, if you want to get into a spin, using the other rudder pedal will come in handy. :)

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Hi, Everyone. This is an important subject and I hope I can help. There is no ABSOLUTE answer to this for all and every aircraft. There are some that behave very differently. The General rule, at least in the way that I teach it, for most of the GA aircraft is:1-Level the wings with the rudder, we have a easy way to remember, Step on the High wing.2-The best thing to do is try to NEUTRALIZE (key word) the Ailerons as soon as possible (at the same time), or after the wings level.3-Lower the nose, just below Horizon.4-Allow the airspeed to build up, if level attitude verified, add power Slowly and as needed.5-Clean the airplane. 6-Climb back to your original Altitude, make sure no secondary stall occurs. All these can / should be done in about 200 Feet, or less.There are other situations and complications that can occur, if you are accelerated, spin etc. but these are the basic/ recommended steps. The most common problems are tendency to Bank to the opposite side, using the ailerons, and secondary / elevator stalls. In the slow / landing, configuration some individuals do not have sufficient strength to manipulate the controls. In real life there is a very heavy force needed to keep a level attitude, the airplane tends to pitch up very quickly, when you add power and trimmed for landing, this produces a secondary stall.I hope this helps.Note: These are the Basic steps, if your Instructor has another procedure you should listen and try to understand, why it different and do what he says until and if you find otherwise, bring it up and discuss it. TV

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I was taught,(when stalling at high angles of roll,like going too steep into a base turn with not enough speed..ie a base leg stall) check forward the yoke and get the plane to a safe speed,then start to sort out the roll with your rudder,then lastly ailerons.Practised it alot..seems to work fine,never gone into a spin.This is because a simple fact of life:To spin you must stall!!! (same as if you want a baby,you need a wumman!!),and if you`ve checked the yoke forward and gained airspeed..your out of danger very quickly.more speed=no stall=no spin.However,i`m a 87.5 hour PPL..and I know there are some VERY experianced pilots on this forum..so I will see what they have to say when I come back later.Interesting one though...

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The "base to final graveyard roll" is a classic accident scenario. A typical setup would be a strong left crosswind (assuming left pattern). When on base, the pilot senses he needs to increase his rate of turn due to higher than expected groundspeed. Because he is flying 1.3 Vs, he is reluctant to increase the bank angle so he cheats by applying excessive left rudder. The gusty wind suddenly changes direction close to the ground resulting in a high sink rate. Aft yoke is applied to arrest the sink, but because the turn is uncoordinated, the left wing drops and he's on his back at 200 ft.

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Hi again,Let me first thank everybody in this thread for their valuable input.According to your replies, I'm quite confident that the way I was taught is probably correct (applying rudder to correct a wing drop during a stall).To refine this issue ( and in order to be completely honest with the old-timers who raised that matter at my FBO), their point was that as soon as you relax the pressure on the yoke, the nose drops below the horizon, airspeed goes up and you're not stalled anymore...therefore (that's the argument)you can safely use your ailerons to raise a dropping wing.The instructors' theory was that no matter what, until you haven't gone back to "straight and level" with adequate speed - you shouldn't touch the ailerons...By the way - this reminds me that we need aircraft that can correctly stall and spin in FS2K2 - Rob Young's Cessna stalled in a very realistic fashion (in Fly!)... I wonder what Peter Sidoli and Geoff Applegate have to say on that topic...Take care - this forum is great Twister

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For fun, ask them next if power controls altitude or airspeed :-lol.The key thing is that your knowledge of aerodynamics has grown as a result of the debate.

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Well, everyone does have there own opinion on this and I guess I'll throw mine out there as well!When I trained for my Private, my instructor always said that if a wing drops in a stall, correct it with rudder input only. Well, when I went for my checkride the examiner during the oral portion asked how to correct for a wing drop in a stall. I said with rudder only. Well, I thought she was going to send me home right there with the look she had on her face. She asked who taught me that and of course I blamed my instructor:-) She then asked if you were to intentionally spin the aircraft, how would you do it? I told her at the stall I would apply full rudder in the direction of the spin. She kinda looked at me like, "yeah, so why would you only correct with rudder if the wing dropped?!" I got her point and we discussed how a wing drop should be corrected with COORDINATED airleron and rudder. The argument she made was that if someone tries to correct with rudder only, they will tend to overcorrect and cause a spin because a spin occurs when an aircraft is uncoordinated. The outside part of the wing is still flying and will work when correcting the wingdrop. I have read many sides to this but it is the way I always taught my students. I have also experimented with it and coordinated rudder and ailerons worked great in the the Cessna. I always demonstrate the "falling leaf" for students when training stalls. You can sit there and hold the aircraft in a power-off stall and even though you are descending, I can sit there and rock the wings back and forth using rudder and aileron. Not once did I ever come close to putting the aircraft in a spin. Now if I sat there and used rudder only, I probably could have spun it. This subject will probably always be debated though!

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>The instructors' theory was that no matter what, until you >haven't gone back to "straight and level" with adequate >speed - you shouldn't touch the ailerons... >As it's been touched on twice in the reply's, ALL aircraft are not the same. Some have varying amounts of aileron effectiveness through stalls. So it's not really as case of "no matter what"!! There are all kinds of devices and designs to change the flow of air seperation from the airfoil. As far as basic instruction is concerned, I'd go with the "rudder" method for raising a wing.And BTW--- If you havn't........... then pic up Rob Young's (RealAir Simulations) Marchetti SF260 for FS2002. Then you can have your simulated stalls and spins for FS2k2. And as I remember from one of Rob's previous postings, the real SF260 does have ailerons that remain somewhat effective in a stall.L.Adamson

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Did I miss something here???This is so simple!!There are two conditions that MUST be met in order for an aircraft to spin.1.) The aircraft MUST be stalled2.) The aircraft MUST be uncoordinated (ball to one side of the inclinometer)If either of the two conditions are not met, then you can not spin (maybe a spiral, but no spin)So, rudder is used to keep the aircraft coordinated (ball centered), who cares if the wings are level or not (this is why the PTS (Practical Test Standards) require Turning stalls).Remember, the only time an aircraft can stall is when the wing exceeds it critical angle of attack. Who cares in what attitude!Boy, the ground lesson could go on, but I am not on the clock here Good luck,JJV

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Hmmmm....This issue seems to be more complex that I thought initially...Let's see if we can sort it out...1. Aircraft of different types behave differently in a stall situation. Some retain more aileron authority than others.2. Apparently, when the nose has dropped and airspeed rises, you can safely use the ailerons without risking an inadvertent spin (provided you relaxed the yoke first).3. When approaching a stall (or during one), a dropping wing can be raised by either the use of rudder (step on the high wing)or by using coordinated input on the ailerons and rudder. Using the ailerons alone is NOT recommended.4. A pilot's instinctive reflex is to raise the wing with the ailerons...perhaps not so when the stall is knowingly initiated and therefore anticipated...but in real life...that's too bad and it causes great concern...5. Advanced wing warping systems should be implemented - let's get rid of the damn rudder once and for all...LOL 6. Emergency Maneuvers Training (look at http://www.richstowell.com/emt.htm ) should be mandatory for ALL pilots every two years.Any suggestions or ideas ?Twister

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I was wondering when someone would chime in with the main point -- there are NO definite rules governing which to use, aileron or rudder, the point is that the wing must be unstalled, and the controls/airplane must be coordinated. The point to be made is that ENTERING the spin is caused by being un-coordinated, and the common error among many of us is to habitually underuse the rudder. So the comment to use rudder to raise a wing would more correctly be to USE enough rudder NOT to drop a wing. Interestingly, the Katana wants to drop a wing in the stall, unlike a Warrior or Cessna. My experience in a T-6 was that the wing dropped like a rock, pretty violent, and that's seen in many warbirds like the Mustang. Try flying a tail-dragger, and you'll understand what a rudder is for. Because the center of gravity is AFT of the wing and mains (unlike the tricycle gear with center of gravity Fore of the mains), it's an interesting machine that wants to turn around and go backwards on the landing/rollout, and fighting the fish-tail is all about rudder. Using rudder to initiate or lead turns or wing-leveling is asking for trouble -- the point is coordination, and anything you need to do to achieve it.

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I'm with you on (1) but I don't think you can apply (2) carte blanche to all situations. Earlier the scenario was described where aileron input could induce the spin due to excessive AOA at the tip. You, in theory, could be completely coordinated while rolling into a right turn which (because of the control inputs) could result in a spin to the left - left wing stalls due to excessive AOA. As the left wing begins to drop, the pilot intuitively applies full right aileron deepening the left wing stall and bam, you were coordinated but now you're spinning. This would be highly unlikely in a Cessna due to their extremely forgiving design, however in many types it would not be that implausible.I believe your reasoning behind (2) is; for a spin to occur, one wing must be (and remain) stalled while the other remains flying (or less stalled - if there is such a thing). You are correct that when in a coordinated turn both wings are producing approximately the same lift and are operating at (about) the same angle of attack which makes a spin less likely to happen. Your capitalization of MUST brings out the debater in me. ;)

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The CG is indeed aft of the mains in a tail skidder, but is NEVER aft of the wings (MAC?) in any fixed wing aircraft that does not have a canard. Stability requires that the nose always be heavier than the tail (from the perspective of the main wing). Or more specifically, Center of Lift must be rearward of Center of Gravity.I do agree with your "habitual undersuse [of] the rudder" statement.Out of curiosity, I pulled both a 172N and a 152 POH off the shelf to see what Cessna has to say. Both show spin recovery procedures as:1. Verify that throttle is in idle position and ailerons are neutral.2. Apply and hold full rudder opposite to the direction of rotation.3. Just after the rudder reaches the stop, move the control wheel briskly forward far enough to break the stall.4. Hold these control inputs until rotation stops.5. As rotation stops, neutralize rudder, and make a smooth recovery from the resulting dive.The emphasis is by Cessna, not me.I guess the original post was regarding wing levelling in a stall, not a spin but the same technique could be argued for both.Interestingly, the 172N suggests that for "more consistent and positive entries" aileron input in the direction of the desired spin should be applied. This is the opposite of what I would have guessed.

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First of all, in reality, if you accidentally enter a stall close to the ground (not paying much attention apparently), you will probably panic and automatically apply aileron correction to keep wings level (as you also JAM the throttle forward). Most pilots know to apply appropriate rudder as well so this should be an automatic reaction and you keep the aircraft in coordinated flight. This isn't so bad. Lots can be said about "you should do this" but the fact is during a situation like this it will all be automatic and based on your recent training and your subsequent default reaction.However, if you fail to keep coordination with the rudder at any time, and especially during an entry to a stall condition (and when jamming the throttle creating your left turning tendancies), your ailerons will work against you, not for you. Adverse yaw could put you into a spin.If you are in/approaching a SPIN situation and the aircraft is leaving coordinated flight then I agree you should not touch the ailerons at all - at this point it's a SPIN recovery hopefully before it even gets started. If ailerons are used at this point then the outcome will most certainly be an aggrivated entry into the spin (direction opposite of the aileron input).I've done about 2 hours of various VFR, IMC and IMC partial panel spin training in the C172 and I tend to go out and have fun with accelerated and deep stalls in almost every new type of aircraft I fly (I don't recommend trying this stuff in a Mooney :( - it can scare the heck out of you and doesn't seem to like to recover from a spin once started). The idea behind that, besides pure fun and getting to know the airplane, is to have recently delt with controlling the aircaft in challenging stall configurations and experiencing how it feels when it is approaching the dangerous side of the envelope. So hopefully you identify/correct and never get into the danger zone and avoid the situation all together, but if you do, your reaction is honed.-Damian[table border=0" cellspacing="30" cellpadding="0][tr][td align = "left"]Damian ClarkHiFi Simulation SoftwareDeveloper of ActiveSkyThe next-generation weather environment simulation for FS2002!http://hifi.avsim.net/activesky[/td][td]http://hifi.avsim.net/activesky/images/wxresmallbanner.jpg][/td][/tr][/table://http://hifi.avsim.net/activesky/ima...][/tr][/table

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>Interestingly, the 172N suggests that for "more consistent >and positive entries" aileron input in the direction of the >desired spin should be applied. This is the opposite of >what I would have guessed. Although it's been nearly ten years, I could swear this is what we were doing many times in the Pitt's S2B during aerobatic practice. The idea was for quck and consistant spin entry in either direction, as desired.L.Adamson

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Many interesting points have been raised in this thread and most are very valid. I was taught (and teach + examine) that any wing drop at the point of stall is 'arrested ' with opposite rudder ... not leveled, this is a very important point. Over use of the rudder can be as bad as Aileron use.I have been lucky enough to gain many thousands of hours on various aircraft from T6 harvards to modern composite types. Throughout all of my flying I have always found this part of the flight envelope the most interesting and at times the most demanding.The stall, as many have said is never straight forward, never textbook, imagine all the variables, CofG, aileron rigging ( I once was unlucky enough to do a post maint test flight on a twin cessna that had the ailerons rigged wrong, believe me cessna twins can bite!), aircraft balance, power setting etc etc. The only thing for sure is that when the airflow can no longer follow a natural flow from leading edge to trailing edge and becomes detached the aerofoil will suffer loss of lift. I will stick with the following;Stall is caused by Angle of Attack .... reduce it ... stick forwardIf one wing suffered loss of lift first (wing drop) use opposite rudder to stop this wing dropping more.When airspeed is sufficient ( different types need more or less) the rudder can be removed and Ailerons used to level wings.The Aircraft should 'Always' be recovered to a climbing attitude.Power should be added to stabalise at normal climb speed and angle.As I said many good points have been raised here. I hope this helps but please remember that every type of aircraft must have it's individual handbook checked to find out the approved recovery for that Aircraft. Placards in cockpits should be read and adhered to.RegardsJohn

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But, going back to theory rather than practice, shouldn't banking into the desired direction of spin lower the angle of incidence at that tip and raise it at the oposite tip?

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NoAirflow is Relative ... If the wing was to go down then for a small moment in time the Relative Airflow is from underneath the wing ... i.e Very high angle of attackA yak 52 stalls at 110-108Kph clean, power off, 1GHowever if you start a decent at say 160 KPH and slowly reduce speed in 10Kph amounts then it will stall at indicated 130 Kph, clean, power off, 1G Reason... The Aircraft has a very high rate of descent and the relative airflow is from below the leading edge ... high angle of attack .... stall

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When I completed flight training at a Piper training center back in 1985, the rule was to smoothly but quickly use coordinated input(all control surfaces as required) in order to achieve reduced AOA and wing level.This was especially important in the "Traumahawk" I trained in.Sarnac

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