Thanks everyone some very interesting responses here.
Don't worry - I wont be doing any practicals by my selvsy for quite some time.

I WOULD like to experience this however so I can appreciate it for what it is. Maybe I'm trying to walk before I can run; but I certainly don't want to find out what it's like when turning off base, onto finals:eek:

Did my annual spin check in the Puchacz glider last weekend. The guy in the back wanted a spin to the right; so, told me to put on a few degrees of right bank and slowly bring the stick all the way back. It seems I cheated by keeping the yaw string straight as the Puch spun left.

Perhaps we should have tried a bit of left bank to get a right hand spin -- or a bit of skid.

Of course the classic spin turning final is a shallow banked turn from a tailwind on base "helped" by a bit of rudder. A well banked turn goes a long way to avoid that.

Trust me, nobody here wants to find that out right there and then.:ok:

I don't know if your club/school offers "unusual attitude" training. Mine does. It starts in the morning with a thorough briefing about stall/spin awareness and execution, and then each participant does a 45-minute flight in an aerobatics airplane (R2160 in our case), loaded within aerobatics limits, to experience precisely these things. As this day is taught by normal qualified instructors, you can already attend while training for your PPL (although you'd have to be quite at the end of the course to get meaningful value out of it) and the hours count towards your PPL experience requirements. (As far as I'm concerned, they should even count double...:)) So check around to see if something like that is offered where you are training.

Alternatively, places like Ultimate High offer Advanced PPL training which includes stall/spin awareness and such.

Final Turn
 

An old ditty around Aero Clubs used to be :

" I watched him spin, I watched him burn, he held off bank in a gliding turn."

Tmb

To the original question from goggles on target. A picture is worth a thousand words, and it's difficult to describe/explain, Hopefully this makes sense:

The angle of both wingtips in space is the same.
The wingtips climb at the same rate, if they were not, you would be rolling.
The inner wingtip moving slower than the outer - otherwise you would not be turning.

As the inner wingtip is slower, takes longer to move a given distance, so will climb more in that given distance than the outer would in the same distance - it is rising at a steeper angle. So, it's angle to the relative airflow is less.

As to experiencing this - I recently did a skills test (converting my license from another contracting state), and was required to demonstrate a stall and recovery off a climbing turn, so I suspect it may well be an exercise somewhere in your training. You'll most likely sit there in a ridiculous attitude waiting for the stall and wondering how on earth anyone manages to do this accidentally.

@bookworm - I know what you mean, and I'm going to have to experiment, but I'm pretty (very) sure i'm not skidding turns! and to 172 driver, I have to say my experience in the 172 is the opposite, perhaps down to rigging differences and / or perception.

And to spinning - glider spinning is a rather different, and more gentlemanly game - the wing drop you get from a C150 is quite violent I'd agree, however, a spin it is not. Provided you're not too shocked (you will be unless it's something you've seen a bit), it can be stopped very rapidly with standard stall recovery and minimal altitude loss - you just fly the wing out of the stall and the problem goes away; it takes quite a while to turn into a spin proper. If however you should start trying to pick up the wing with aileron, and persist in holding the stick back, they you truly are in trouble, ditto if you happen to wait until you're upside down before doing anything about it. Personally I subscribe to the glider stall recovery of getting the nose down pronto, I don't like this powered idea of keeping a relatively flat attitude and hauling it out with power.

That's true enough for a climbing turn, Mark -- it's the "staircase" that was used as an analogy earlier -- but here's the passage Goggles quoted from Pratt (I don't have the book so I can't verify it)

The claim is that the outer wing has a higher AoA than the inner wing in a level turn. I don't believe that it's true.

Ah, yes.. RTFQ. Doh!

Goggles on Target

Suggest you google: See How It Flies--J.S.Denker
Read Sections 8 & 9 for the answer to your question.

If you're not aware of this internet resource it is an online book written by a flight instructor who also happens to be a Physicist.It is the finest account of the fundamentals of flight that I have read (and I've read quite a few.)Aimed specifically at us (amateurs at the light end of aviation) so nothing on mach effects/jet turbines etc. Since I have only a rudimentary grasp of mathematics, physics and aerodynamics I am not in a position to be critical of the text but practising Aerodynamic Engineers that have posted on these forums in the past have recommended it.

Read and understand why a statement like:
" dihedral provided some stability in roll. The wing which - as a result of a disturbance around the roll axis - becomes more horizontal is going to produce more lift, and thus counter the roll"

is wrong.

This text coupled with Stick and Rudder by Langewieschie should be required reading in any flight training.

TIM

• BackPacker - Thanks, I'll look into some advanced SSA when I have a few more hours in my log book, I think it will be invaluable.
• BookWorm - Thank you, You got it :D You indeed, RTFQ:}
• RansS9 - That's an awesome resource, thanks.

So the quote from PPL1 could read:
“When turning there is an increased tendency for the wing to drop at the stall, but not in the way you might expect. In a balanced level turn, the higher (outer) wing has a higher angle of attack than the lower wing because the pilot has to deflect the ailerons against the turn due to the faster (higher wing) producing more lift than the inner. Therefore the higher wing will reach the critical angle of attack first and stall, actually rolling the aircraft out of the turn.”????

If this level turn is balanced it would indicate that some power & trim had been applied to maintain this balance. If the turn is balanced the aircraft must be travelling at a constant airspeed. Therefore although the outer wing is describing a greater diameter than the inner wing, the two wings are balanced by nose up trim & power+. How can the a/c stall in such a balanced condition? & why would the outer (faster) wing stall first in the unlikely event that the laws of physics have been broken?
I have set my Emeraude up in a balanced level turn & taken the hand off the stick to take photographs, it takes a bit of care to get it balanced well enough & ensure it is going to stay there, but not a problem. I must try it one day to see how long it will stay balanced before it falls over!

I've been required to demonstrate a stall and recovery off a descending turn, the spin-in-from-final-turn scenario, and I was left wondering how on earth anyone manages to do this accidentally.

But I know that they do, and that they die.

What this has done to me is make me very careful when I misjudge the wind on base leg and overshoot - I try to recognise the scenario and positively think to myself "shall I chop the power and tighten the turn, or shall I do something more sensible?".

Oh dear, is power really needed for a balanced turn ? That's me screwed in my glider then ;-(. Being serious, constant speed can be achieved by attitude and not just throttle. Furthermore a wing stalls when the critical AoA has been reached and this is expresssed as AoA relative to airflow not necessarily direction of travel. Also a wing is 'stalled' when the drag it generates exceeds the lift it's generating. So, it's entirely possible for a wing that's travelling physically faster (but with a higher AoA) to be generating an excess of drag over lift than the 'slower' wing. Throw in the square rule for lift and drag and you'll see that any situation where drag > lift is further exacerbated by speed!

Stalling in a turn is no different than stalling with the wings level; recover the same, fly the same; it's the same airplane. It hasn't become a different airplane.

You shouldn't need stick into the turn our agaist the turn. In fact, in most light general aviation airplanes, a standard demonstration to the student should be a hands-off steep turn in which the instructor puts the airplane in a 45 degree bank, trims it for pitch, then lets the airplane fly around the turn hands-off.

That said, the aircraft, loading, degree of bank, and center of gravity do play a roll, and not all aircraft respond the same, or are flown quite the same.

For most light production airplanes, a stall in a turn is a non-event, every bit as much as it is straight and level.

Keep the inclinometer ball in the center with your feet, and fly the airplane, Whether it spins or not is entirely up to you. So far as the 150 and 172 previously mentioned...one has to work to make them spin. They don't bit agressively out of a simple turn unless the pilot isn't coming close to doing his job.

No, throttle isn't needed in a balanced turn, but it is in a level balanced turn. A level balanced turn is rather difficult in a glider unless there is lift from some other source?? In which case you would be unscrewed.:ok:
Attitude can control speed, but not level flight. I had a glider once, a K6E, it would only fly downhill:confused:

Crash one, gpn01 - I think in general parlance, and almost certainly in the example cited, a 'balanced' turn is taken to be one where you are neither slipping, nor skidding - i.e. the longitudinal axis of the aeroplane is aligned with where it is going, no particular consideration of airspeed.

Sorry but I disagree just a bit. The original question referred to a balanced level turn. This would imply a constant airspeed, it would have to be in order to be both level & balanced. More power would be reqd than for the same airspeed in a balanced level cruise.

Isn't the manuevor as described by the OP an FAA accelerated stall? (A standard PPL requirement)

My recolection was simply a faster break with a bit more pronounced wing drop (dependent primarily on how well coordinated the turn was), but at quite a bit higher airspeed (exactly as described by Denker)

Please explain this then guys.

Wings stall at an angle of attack, not a particular speed.

An aircraft in a steady balanced level turn is developing the same amount of lift from both wings, otherwise it would be rolling.

The outer wing is travelling further than the inner wing (in the same time, of course,) therefore it is going faster.

Since the amount of lift developed by a wing varies according to speed and angle of attack (and a constant) , if both wings are developing the same lift and one is going slower than the other the slower wing must have a greater angle of attack.

If speed is decreased the angles of attack must increase to maintain level flight The wing with the greater angle of attack, the slower one, must stall first.



During the fifties and sixties both Cessna and Piper were spending vast amounts of time and money to develop aircraft that were easier to fly, ( 'A plane in every garage,') and less easy to crash. Along the way some of the aircraft gained unusual handling characteristics.

I did turning stalls as a part of the FAA CPL in a 172SP, at many angles, along with all sorts of other stalls like accelerated stalls. I never spun once, recovery is the same - reduce the AOA of the wings and don't hit the ground.

Perhaps post-PPLs in the UK should be encouraged to explore the envelope rather than scare them off with scare stories of spinning and death?...that is if they can find an instructor who is not too scared...?

Couldn't agree more - both that it's harder to spin than most think, and that spinning should be experienced at some point. Pretty sure nobody said don't, but don't go and do this on your own. 90% of folks have no idea where the edges of the envelope are, or what they feel like, which is both a waste of capability, and in my opinion dangerous.

However, this is another pprune debate which borders on holy war. Expect someone from the anti-spinning brigade along shortly using words like 'macho rubbish', etc.