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Practicing stall recovery, the fabled base to final turn with engine failure

Physics isn't a matter of opinion

I've only been flying 4 years but I do know Physics, having done a PhD in the subject and postdoctoral research beyond that. Even though I'm from the UK, I'm with the Americans on this one: there is absolutely no way that an aircraft flying in a uniform wind (ie no wind shear or gusts) can respond differently from one flying in a windless sky (neglecting tiny effects due to the rotation of the earth). In particular its airspeed will be the same function of attitude and power in both cases. All inertial frames of reference are equivalent - this is one of the two founding principles of Special Relativity so if you disagree then you'll need to take it up with Einstein!

I'd hate to think of someone stalling in an upwind turn because they were confident their airspeed was going to increase....
 
"there is absolutely no way that an aircraft flying in a uniform wind (ie no wind shear or gusts) can respond differently from one flying in a windless sky"

This is certainly true and furthermore, if there was any additional effect on an airplane's airspeed due to turning in a steady wind, the effect could be calculated and mathematically expressed.
 
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"there is absolutely no way that an aircraft flying in a uniform wind (ie no wind shear or gusts) can respond differently from one flying in a windless sky"

This is certainly true and furthermore, if there was any effect on an airplane's airspeed due to turning in a steady wind, the effect could be calculated and mathematically expressed.

If the airplanes are in steady, straight flight in a steady wind then this is true. But turning flight, as Mac says in his article, is the same in terms of the airplane as wind shear. And transition through the wind profile is like stepping on the moving sidewalk. The accelerations occur in this transition. And turning flight is another transition.

An IRU can calculate the effect just fine. Well, actually it doesn't calculate it, it measures it via precision accelerometers, because the wind does act on the airplane. If it could not detect the effect of wind then 2 airplanes flying at airspeed X for time T, one in a 100mph wind and the other with 0 wind would, according to the IRU, end up in the same place.

Think of the Draper B29. It flies across the continent, probably through 3 or 4 weather systems, encountering winds from all directions, perhaps some of them as high as 100mph or more. They would have a massive impact on the flightpath. If the Iru got them to the right place, then it had to sense those accelerations along with the accelerations due to lift and thrust and control inputs. If there were no accelerations due to wind, how could the iru keep the airplane on course? It would be impossible.

This is repeated 1000s of times a day in every iru equipped military and civil iru equipped airplane. It ain't a theory.
 
Go try it. From a power off 65-70KT approach, enter a full deflection slip with a flap setting of your choice - i.e. full. Now ease the stick back as if you had "creeping hand" syndrome. Pull it to the stop while keeping the full slip inputs. If you can produce a spin from this, you've produced something I've always failed at.

The explanation for this is pretty straightforward: In the slip, the HS is partially blanked by the fuselage, and in turbulent flow. In many (not all) airplanes, it's difficult or impossible to produce enough downforce with a blanked elevator to increase the angle of attack enough to stall.

It's good fun to try it (at a safe height) though. If you've internalized the idea that uncoordinated flight with the stick behind the critical angle of attack position will cause a spin, it's entertainingly eye-opening to discover a corner case where it doesn't happen.

Another surprising aspect of this: Once you're in a full-rudder-deflection slip with the stick all the way back, slowly back-off the rudder: You'll probably find that pitch rises as you gain elevator authority, and at some distance from full rudder deflection you'll get a pretty rapid departure into a spin.

- mark
 
Okay, it's settled. The basic laws of physics work everywhere except Canada.

(What is true is that everytime the wind or other things, like tire friction, change, the airplane accelerates until it is in equilibium with the air mass, and the INS measures those changes and keeps track of them. Once in equilibrium the INS does not measure any further changes if the airplane is flown straight and level. But from the past history it knows about the wind, and the INS keeps track of the true course over the ground.)
 
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Okay, it's settled. The basic laws of physics work everywhere except Canada.

(What is true is that everytime the wind or other things, like tire friction, change, the airplane accelerates until it is in equilibium with the air mass, and the INS measures those changes and keeps track of them. Once in equilibrium the INS does not measure any further changes if the airplane is flown straight and level. But from the past history it knows about the wind, and the INS keeps track of the true course over the ground.)

Yes that's pretty much it. Although it doesn't know where the acceleration comes from, whether it is wind, thrust, drag etc. It just senses the acceleration. Which proves that the wind produces an acceleration whenever it changes relative to the airplane in magnitude or direction (which includes the airplane turning). And last time I checked it works in Canada too.
 
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(pounding my head on the concrete!)
Yes, viewed from the ground, the wind accelerates an airplane. But viewed from a hot air balloon, it does not, because there is no wind! Having both of these points of view be correct, and produce the same observables, is exactly what is so hard for people to accept (100+ years ago most scientists did not accept it either). But today the concept is fundamental to modern physics. The calculation in the ground based reference frame is complicated. But in the balloon frame, it is simple. In that reference frame there are no effects on the airplane (no accelerations other than turning) and the turning effects are independent of direction (no wind!). It is a simple matter to translate the results back to the ground based reference frame. Either method will produce the same results. But the balloon frame has much simpler calculations, and easily shows that the effects on the airplane are independent of any wind.
The dangers of the downwind turn are due solely to wind shear, or pilots looking at the ground and trying to follow a ground track. It has nothing to do with aerodynamics with or against the wind.
 
If the airplanes are in steady, straight flight in a steady wind then this is true. But turning flight, as Mac says in his article, is the same in terms of the airplane as wind shear. And transition through the wind profile is like stepping on the moving sidewalk. The accelerations occur in this transition. And turning flight is another transition.

the moving sidewalk analogy is a good one, but I would suggest that Mac is using it wrong. Flying an airplane in a steady state wind is like being on the moving side walk. Run forward, run backward, run in circles, it won't make a difference to you as long as you're on the sidewalk. If you're walking in circles on a moving sidewalk you won't stumble when you transition from "upwind" to "downwind" because you and the sidewalk are moving together, just like an airplane in a moving airmass.

The stumble occurs when you step off the end and the sidewalk has suddenly stopped, which is analogous to wind shear, not turning from upwind to downwind. I don't think anyone would argue that your airspeed would change if you're 20 knot headwind suddenly disappeared. We have a name for this, it's called wind shear.
 

I imagine there must have been some fun conversations among the staff of Flying Magazine when Mac was editor. Peter Garrison has written more than once on the subject of downwind turns, going back as far as 1970:

https://books.google.com/books?id=BZ0thq_qwNQC&pg=PA58&lpg=PA58&dq=those+terrible+downwind+turns&source=bl&ots=UgiAnC10lL&sig=Oi1oDVbDOCTVClOsSxeFfgyMtdE&hl=en&sa=X&ved=0ahUKEwj2joXl-PfMAhUGOVIKHUmWDnkQ6AEIKjAE#v=onepage&q=those%20terrible%20downwind%20turns&f=false

Its pretty clear that Garrison and Mac do not see eye to eye on the subject.
 
I came across this thread while searching for another topic. For those that have not seen it, I was compelled to write this message and bring it to the top today. Hopefully, someone that needed to see this, saw it as a result.

The first post is really all you need to read / watch.

Fly safe.

Chad
 
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I watched it years ago and it is just as freaky now. I can see how easy it is to go around. Thanks for the reminder and I plan to bookmark it or download.
 
The first post is really all you need to read / watch.

Fly safe.

Chad

This is an excellent video and good reason why RVers should get some training in basic aerobatics and unusual recovery. Note the difference in recovery procedures. The instructor smoothly rolled through the skidding stall with nominal altitude loss whereas the pilot froze, stopped the roll half-way through, and put the plane in a nose low attitude. Yikes!

Go out and find a good aerobatic instructor and spend some time practicing unusual attitude and spin recovery procedures. Do it to the point where it is second nature. Have some fun and fly safe.
 
I went up to practice the "impossible turn" the other day. This was my first attempt and it wasn't very good. My best glide is ~90 KIAS and I let my speed build up in the turn. I was too focused on watching the AoA and not falling out of the sky. The AoA was in the red at first, but backed off as my speed built up. I applied back pressure to slow down but that only steepened my turn as in a spiral. Any critique by more experience pilots would be very welcome. (My new Virb Edit update defaulted to MPH rather than Knots. Sorry)

https://www.dropbox.com/s/ukkugp8p6aeex4a/2018-04-01 Impossible Turn 2.mp4?dl=0
 
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