Flight dynamics - stall management controversy...

[Avcomware 1]

Hi. Just a quick point on

[Guest]

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.

[Guest]

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. ;)

[Guest]

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.

[Damian Clark 948]

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

[LAdamson 240]

>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

[Guest]

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

[Guest]

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?

[Guest]

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

[Guest cbuff]

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

[Guest]

One exercise you might want to try with an instructor is something called a falling leaf. Its really neat, I did it in EMT (emergency maneuvers training) and what you do is stall the aircraft and keep it stalled while the dropping one wing and recovering and dropping the other wing and recovering. You alternate until its time to recover. Basically you're preventing the wing from dropping, thus preventing a spin. The reason why its called a falling leaf is because the airplane sorta looks like a falling leaf when performing this maneuver.