Thanks for posting that.

Can you post the section on maximum turn performance recommendations from the Spitfire Mk I Operating notes so that all can read it?

I think the participants will have a better understanding of what I said earlier:

Crump you are mixing terms .... early in this discussion you introduced the term Aggravated and then picked up on Accelerated as others started to use it. Aggravated in terms of aerodynamics is not a common term. The Alpha pdf you refer to is the first time I have seen it used this way. The use of the term Accelerated with respect to stalling refers to to Stall entry at greater than 1G, to do this obviously requires higher IAS to generate the additional G at the same critical AOA. So by definition An Accelerated Stall is a stall at greater than 1G. In our Spitfire discussion where structural damage was being referred to we were describing a Spin entered from a high G accelerated stall departure with subsequent excessive G (notatably rolling G which is usually dramatically lower limit than the usual quoted symmetrical G limit)

Now as to thinking about controls and accelerations at spin entry as you suggest. A standard copybook 1G stall and spin entry has you arriving at the Critical AOA in 1G flight with close to full backstick. As the stall develops (ideally a nanofart before) you smoothly apply and hold full rudder (I guess you could say this is "aggravating" the stall ). The aircraft will then autorotate and (in most cases) if the controls are held it will stabilise in a spin. That is a classic 1G un-accelertaed stall spin entry. At the departure point you are already at max AOA (at or close to full backstick at 1G) so dont have the ability to increase G therefore the stall is un-accelerated.

Is this the section you wanted posted from the Spit I pilots notes ?
http://img577.imageshack.us/img577/7397/spitturn.jpg

Sounds pretty standard to me, Max turn performance in a conventional straight wing aeroplane.

Turning just short of critical AOA is a pretty basic fighter pilot skill. The Stall buffet in many aeroplanes has "depth" and differences in the degree of buffet that can be felt through the stick. As the AOA is eased on the first clues is a low intensity buffet described in some circles as the "Buzz" as the AOA increases the buffet gets harsher (Buzz turns into buffet) eventually you get to critical AOA and the stall ocurrs. Embryo military pilots are taught to feel the subtle differences in the buffet. Max performance turning is done "On the Buzz". A standard exercise is to do this whilst airspeed and G are changing whilst holding the aeroplane on the Buzz throughout without reference to AOA instrumentation etc ... just by feel.

In the more modern types (FBW with active leading and trailing edge flaps etc) high AOA capabilty and aerodynamic configuration has you in a lot of buffet any time you are close to max turn performance ... typically in the 25-30 degree Alpha regime (except in the pussy low AOA limited F16 :). As such AOA cueing via instrumentation or audio is there to help you get the max out of the jet though there still is a certain tactile feel to just how deep into the buffet you really are.

Every pilot, be they Axis or Allied attested to the Spits flying ability.
Disregarding the BoB, at the end of the Malta aircampaign the attrition rate was 1 allied loss for every 10 LW/Italian confirmed kills. Beurling (Spit Mkv) scored 3 BF109 kills and a Ju88 in one sortie with 29 Kills over the few months he was flying in that campaign - that tells me more than any data sheet!

Now THAT's the evidence we definitely needed. *giggle*

I was taught to pull to the 'nibble', just a slightly different colloquialism I suspect.

The 'depth' of the buffet is due to washout I suspect, and very indicative of the progressive nature of the stall along the span. With light buffet, a very small inboard section of the wing has actually exceeded alpha max, but the remainder of the wing is at or near CLmax.

W.

Nobody is mixing terms.

Sure it is a common term.

http://profs.sci.univr.it/~zuccher/d...DS_JOA2007.pdf

Any stall under any acceleration is aggravated. Anytime you have uncoordinated flight, you have lateral acceleration.

http://books.google.com/books?id=nxb...flight&f=false

http://faculty.chicagobooth.edu/john...C%2061-67C.pdf

It is and I did not ask you to post it because of some abnormality. I asked you to post it because it specifically warns the pilot NOT to fly in the buffet zone and even to ease off the stick by pushing it forward.


Only in modern FBW....

Aerodynamic buffeting will not increase your turn performance, it will degrade it.

And that "buffet" has nothing to do with the aerodynamics of the aircraft. It is a programed stick shaker placed there by the engineers to let the pilot know he is nearing stall speed and is "On the Buzz" at the point the stability and control engineers put it.

Watch from 3:50 on to get a better idea what we are discussing. When you see those little pieces of sting stand straight up and then reverse, that portion of the wing is stalled.

That stall progresses if the pilot continues to increase angle of attack to CLmax until the wing can not longer support the weight of the aircraft and is no longer flying.

That flow reversal over a portion of the wing is what causes aerodynamic stall buffeting.

At 4:29 the test pilot begins recording a "light" buffet. Observe the tufts and imagine a "heavy" buffet....

http://www.youtube.com/watch?v=dUj6rmgku10

An airplane does not increase its turn rate if it experiences aerodynamic buffeting. An airplane that buffets will decrease it's turn rate when the buffeting begins.

When artificial means such as stick shaker were not available, the only choice a designer had was to reduce the amount of stall warning he gave the pilot. The less buffet, the closer the pilot can fly to CLmax without degrading his turn performance due to aerodynamic buffeting.

Crump you said :

"It is and I did not ask you to post it because of some abnormality. I asked you to post it because it specifically warns the pilot NOT to fly in the buffet zone and even to ease off the stick by pushing it forward."

Guess what you do when you go past the Buzz and get into the buffet ... you ease the back pressure off to get back into the Buzz .... Ideally the very first hint of it. Thats the art of max performance turning.

Then in response to my statement:

"Max performance turning is done "On the Buzz". A standard exercise is to do this whilst airspeed and G are changing whilst holding the aeroplane on the Buzz throughout without reference to AOA instrumentation etc ... just by feel."

You said:
"Only in modern FBW...."

Ok you are really off the plot in this response and thats just wrong.
I learnt to fly on the "Buzz" in a Winjeel and then on MB326H aircraft. Both Cable and or Manual push rod controls no Hydraulics or FBW. I also do it regularly in a YAK52. Whether you like it or not thats the way you practically get max turn performance in conventional straight wing aircraft. You want to get pretty close to Clmax to do achieve that, without an AOA gauge the first onset or the buzz IS the cue that is used. I am not the only one posting here to that effect.... see RAF_Wingers post.


You then said
"Aerodynamic buffeting will not increase your turn performance,it will degrade it."
No argument I didnt say that.... but see above response.....

You then said;
"And that "buffet" has nothing to do with the aerodynamics of the aircraft. It is a programed stick shaker placed there by the engineers to let the pilot know he is nearing stall speed and is "On the Buzz" at the point the stability and control engineers put it."

Sorry mate but with respect thats just total crap, and shows you dont really know what you are talking about. The fighters I have flown operationally the Mirage III and F18 Buffet like hell as soon as you start to get some Alpha on the jet. The Mirage III is even in buffet in the circuit ! ..... nature of the beast..... neither type has a Stick shaker or Stick Pusher system

As to Stick shakers I have flown 2 types that were equipped with these ... both commercial transports that required them certification wise both conventional Hydro mechanical controls.

Now I dont know your background Crummp but if you had some practical experience in realitvely high performance straight wing aerobatic aircraft and had been taught how to get the maximum out of it you wouldnt be saying the things you are.

Here is someone elese's view on this. The text is from a civilian Aerobatics manual. The author a qualified Military Test pilot and graduate of ETPS... and even referring to an Aeroplane with a typical WWII type wing.
The last line says it all.

http://img534.imageshack.us/img534/6210/buzzburrble.jpg

Lets put this into a practical example that is a realistic life or death situation that requires your best possible turn performance in this case Min radius.

Lets say you find yourself 90 degrees nose down pointing at the ground. You are unsure if you have sufficient height to pull out you may or may not but you must give it your best shot. How would you fly the recovery ? Any delay makes the problem worse, you need your best Turn RFN. Get it right you live get it wrong you DIE.