Tiger at Pimpama
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.....I think, if Angle of Attack instead of Pitch, was taught as the 'Primary' effect of the elevator,......
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27/09 what you say is correct. However at high airspeeds from level flight when you increase the back pressure the aircraft doesn't immediately stall does it? It climbs until you run out of airspeed, or completes a loop. Continue increasing back pressure and the aircraft will continue to increase its angle of attack to the relative airflow until it stalls. Where? Around 16 degreesd angle of attack.
A dynamic stall can occour from any airspeed or attitude, how? Increase the angle of attack beyond the stalling AoA. Again around 16 degrees to relative airflow, depending on the aircraft.
Point being, there is only one critical angle of attack for each aircraft configuration, and it does not vary with airspeed. What controls AoA? Stick position.
A dynamic stall can occour from any airspeed or attitude, how? Increase the angle of attack beyond the stalling AoA. Again around 16 degrees to relative airflow, depending on the aircraft.
Point being, there is only one critical angle of attack for each aircraft configuration, and it does not vary with airspeed. What controls AoA? Stick position.
How about we all agree that both arguments are two ends of the same thing? Just because I put my stick at one spot does not necessarily mean I am at the same AoA as the last time I put it there though it will likely get there eventually (Of course full back stick would probably be an indication that I'm likely to stall, I don't disagree there) and just because my airspeed is low does not necessarily mean I am definitely about to stall, IMHO it comes down to knowing your Aircraft and listening to it what it's telling you, simply using JUST your Airspeed OR Control Column/Yoke/Stick to tell you whether you're about to stall would be ignorant of the whole picture.
In the end a man has lost his life and another young man has had his permanently scarred, this particular willy measuring argument is really a moot point without know what has actually happened which I don't think anyone but Ryan will be able to tell us, if he hasn't suffered some kind of memory loss.
I have no problem with speculation, but what in the picture or evidence so far suggests that a stall was the cause anyway? I think we've already established from others that the Aircraft did infact come to rest in the position most of the photos show as opposed to inverted as some have heard so it seems to be a incorrect suggestion now anyway.
We do know there were blustery conditions, we do know the Tiger Moth can be a handful in such conditions, perhaps he just got plain ol' fashioned unlucky and mother nature took over. It happens as I'm sure quite a few of us on here have first hand knowledge of, sometimes you're just the poor bloke holding controls when it happens and from then on you're just along for the ride.
In the end a man has lost his life and another young man has had his permanently scarred, this particular willy measuring argument is really a moot point without know what has actually happened which I don't think anyone but Ryan will be able to tell us, if he hasn't suffered some kind of memory loss.
I have no problem with speculation, but what in the picture or evidence so far suggests that a stall was the cause anyway? I think we've already established from others that the Aircraft did infact come to rest in the position most of the photos show as opposed to inverted as some have heard so it seems to be a incorrect suggestion now anyway.
We do know there were blustery conditions, we do know the Tiger Moth can be a handful in such conditions, perhaps he just got plain ol' fashioned unlucky and mother nature took over. It happens as I'm sure quite a few of us on here have first hand knowledge of, sometimes you're just the poor bloke holding controls when it happens and from then on you're just along for the ride.
Myth Busting
Ladies and Gents,
I don't believe it is appropriate to engage in public discussions about this accident (or any other) before the facts are known. However, the "absolute" advice on stalling being given in this thread concerns me and needs rebuttal.
Stick position may be useful as a cue as to approaching stall – but no more than a cue. Just as IAS, airflow noise, ineffective (“sloppy”) controls, high nose attitude and all the other “cues” that are taught in basic stalling exercises are just cues that may assist - but are not always valid.
Sorry, but the stick position at stall will vary with C of G, acceleration and deceleration rates, flap position, thrust (power) and, in some aircraft, trim position.
In a pure aerobatic aircraft, where aeros are usually performed at a (more or less) fixed fuel load with a given pilot weight and no baggage / freight (fixed C of G), clean aircraft and a set trim position (not normal to trim into aerobatic manoeuvres) the “fixed stall stick position” may be valid. However, for many other cases experienced every day in GA (even a simple C172 with 1 POB versus 3 – 4 POB) the fixed stick position premise is not valid and, if taken as gospel, can be dangerously misleading.
It is just as incorrect to say that an aircraft will always stall at the same stick position as it is to say it will always stall at the same IAS. Both are true for any given set of variables. Change the variables and both are quite wrong.
Stick position is just a cue.
Fly Safe PJ
I don't believe it is appropriate to engage in public discussions about this accident (or any other) before the facts are known. However, the "absolute" advice on stalling being given in this thread concerns me and needs rebuttal.
Stick position may be useful as a cue as to approaching stall – but no more than a cue. Just as IAS, airflow noise, ineffective (“sloppy”) controls, high nose attitude and all the other “cues” that are taught in basic stalling exercises are just cues that may assist - but are not always valid.
Sorry, but the stick position at stall will vary with C of G, acceleration and deceleration rates, flap position, thrust (power) and, in some aircraft, trim position.
In a pure aerobatic aircraft, where aeros are usually performed at a (more or less) fixed fuel load with a given pilot weight and no baggage / freight (fixed C of G), clean aircraft and a set trim position (not normal to trim into aerobatic manoeuvres) the “fixed stall stick position” may be valid. However, for many other cases experienced every day in GA (even a simple C172 with 1 POB versus 3 – 4 POB) the fixed stick position premise is not valid and, if taken as gospel, can be dangerously misleading.
It is just as incorrect to say that an aircraft will always stall at the same stick position as it is to say it will always stall at the same IAS. Both are true for any given set of variables. Change the variables and both are quite wrong.
Stick position is just a cue.
Fly Safe PJ
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simple solution, go and practice stalling yourselves... (when was the last time you did that truthfully?) and try it a differing weights, load factors, CoG positions, and come back and tell us what you find..
as for Ryan, im sure he will tell us himself what happened via the investigation. at this point there are to many variables at the time of the incident to come up with a reasonably close assumption of what might have happened.
as for Ryan, im sure he will tell us himself what happened via the investigation. at this point there are to many variables at the time of the incident to come up with a reasonably close assumption of what might have happened.
simple solution, go and practice stalling yourselves... (when was the last time you did that truthfully?) and try it a differing weights, load factors, CoG positions, and come back and tell us what you find..
A mid-CG position of about 24.5% MAC is the first configuration. For reference, cruise at 140 kts, the stick position was 290 mm aft of the instrument panel. At full throttle the stall stick position was 320 mm aft of the instrument panel. At idle it was 360 mm.
For the next flight CG now at about 27.5% MAC. Stick position at 140 kts still at about 290 mm. Stall stick position is about 295 mm at idle.
(Incidentally, in an inverted stall the stick position was 215 mm at idle.)
For one particular Lancair 360 there was a difference in stick position at the stall of about 50 mm between 10 deg flap and 30 deg flap. Not a lot of difference at all in stick position between stall and a much higher speed at the same flap setting.
Try a S&L power off stall in a Decathlon then do a loop and see that the stall stick position is much further aft with full throttle at double that stall speed with more than 4 G. As Propjet88 says, it is a different matter in a more rigid airframe and control system such as the Pitts.
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stalling
Without going too over the top with aerodynamic theory, DJPTL is on the mark.
During a 'certification stall', maintenance of height is irrelevant as the procedure requires a loss of airspeed of one knot per second. You are looking for the 'g break' as there is no definitive definition of what a 'stall' actually is.
For civilian aircraft, the one g stall speed is essential for further performance calculations. A 'handling stall' as practiced by most flying schools, involves 'minimum height loss'.
These manoeuvres are two different beasts.
CG position, longitudinal static and longitudinal dynamic stability are significant factors.
It is not possible for example, to stall some Jabiru models two up with a significant fuel load.
For the DH 82, it is possible to be in level flight, unstalled, with zero IAS and full back stick. It won't stay there, but you can get it there.
Stick position? Muscle memory? Not very reliable indications.
In fact, as DJPTL alluded to, the difference in power on versus power off stick position is also reflected in the measurable (with the right instrumentation in complex aerodynamic configurations) difference in these speeds and the difference should not be more than .5 of a KIAS (from memory).
For all the clues that should be obvious to the pilot to indicate the approach of a stall, stick position sits 'well back' in the queue.
Excuse the pun.
During a 'certification stall', maintenance of height is irrelevant as the procedure requires a loss of airspeed of one knot per second. You are looking for the 'g break' as there is no definitive definition of what a 'stall' actually is.
For civilian aircraft, the one g stall speed is essential for further performance calculations. A 'handling stall' as practiced by most flying schools, involves 'minimum height loss'.
These manoeuvres are two different beasts.
CG position, longitudinal static and longitudinal dynamic stability are significant factors.
It is not possible for example, to stall some Jabiru models two up with a significant fuel load.
For the DH 82, it is possible to be in level flight, unstalled, with zero IAS and full back stick. It won't stay there, but you can get it there.
Stick position? Muscle memory? Not very reliable indications.
In fact, as DJPTL alluded to, the difference in power on versus power off stick position is also reflected in the measurable (with the right instrumentation in complex aerodynamic configurations) difference in these speeds and the difference should not be more than .5 of a KIAS (from memory).
For all the clues that should be obvious to the pilot to indicate the approach of a stall, stick position sits 'well back' in the queue.
Excuse the pun.
Last edited by actus reus; 31st Dec 2015 at 05:19. Reason: Bad wording
50 50:However at high airspeeds from level flight when you increase the back pressure the aircraft doesn't immediately stall does it?
50 50:It climbs until you run out of airspeed, or completes a loop.
Sad for the family of the pax. Ryan is likely to have a long recovery, physically and mentally. I wish him the best.
I wonder why he is doing this job in the first place, doesn't he want to fly buses? I'm surprised he's not already with Q'Link or similar.
I wonder why he is doing this job in the first place, doesn't he want to fly buses? I'm surprised he's not already with Q'Link or similar.
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If you attempt to snap roll an aircraft from high speeds two things will happen. It will snap......it may roll. Snap rolls are usually conducted at relatively low air speeds and can be negative snaps with a rapid forward movement of controls. However the application of full rudder prevents the aircraft looping.
High speed snap rolls in something like a decathlon will result in a compression fracture of the leading edge near the wing root. You can attempt to pass it off as hangar rash but nobody will believe you.
High speed snap rolls in something like a decathlon will result in a compression fracture of the leading edge near the wing root. You can attempt to pass it off as hangar rash but nobody will believe you.
However the application of full rudder prevents the aircraft looping
High speed snap rolls in something like a decathlon will result in a compression fracture of the leading edge near the wing root. You can attempt to pass it off as hangar rash but nobody will believe you.
Comment Issue No. 2 states 'the FAA has determined that wing damage incidents are the major cause of compression cracks and other spar damage in low horsepower and lightweight airplanes.. therefore a one-time inspection is acceptable...' but give no indication of in-flight causes in any of the affected fleet, nor a rationale for the differentiation.
Folks,
I am advised that this aircraft was in Limited Category, and therefor administered by Australian Warbirds Association Ltd, and the first fatal accident since AWAL assumed such responsibilities from CASA.
That, and the fact that, in Queensland, an aircraft is a vehicle for the purposes of the Queenland Criminal Code, will be additional complications for the somewhat limited experience PIC of the aircraft.
Tootle pip!!
I am advised that this aircraft was in Limited Category, and therefor administered by Australian Warbirds Association Ltd, and the first fatal accident since AWAL assumed such responsibilities from CASA.
That, and the fact that, in Queensland, an aircraft is a vehicle for the purposes of the Queenland Criminal Code, will be additional complications for the somewhat limited experience PIC of the aircraft.
Tootle pip!!
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I thought AWAL had responsibility for at least other DH82 fatal accident in Queensland, the one caused by the spar mounting bolt that that failed after it's thread cut rather than rolled?
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djpil, I am sure there is a very good reason you don't allow snap rolls in your own Decathlon. The one I am referring to was "Displayed" at very low level at YNRM in the not too distant past with the above mentioned result. No external markings would indicate no impact and a leading edge with the structural integrity of a soggy violet crumble indicates damage.
VNE220, a full rudder imput would certainly put the aircraft out of balance.
VNE220, a full rudder imput would certainly put the aircraft out of balance.
Nope!
Compression fractures are only applicable to wood structures i.e the wing spars. It was the trailing edge that failed not the leading edge. The trailing edge is a very light sheet metal V shaped strip. It failed because the wing rib had failed.
Compression fractures are only applicable to wood structures i.e the wing spars. It was the trailing edge that failed not the leading edge. The trailing edge is a very light sheet metal V shaped strip. It failed because the wing rib had failed.