Spit IIa

[RAF74_Winger]

Originally Posted by Crumpp

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.

Well, it doesn't actually say that - as given: "Even if the aeroplane does not begin to shudder or otherwise indicate an imminent stall, it may not be turning quite as quickly as it would if the stick is very slightly eased forward."

As has been said before - the buffet region of flight has 'depth' due to washout and the progressive nature of the stall across the wingspan. It's possible for a pilot experienced on type to know how much he can pull through the buffet before a full-blown stall & consequent stall and/or flick will occur.

The 'buzz' or 'nibble' does not necessarily presage an imminent stall, it just indicates that the inner part of the wing has exceeded max AoA, the airflow has separated from that surface and is impinging on the elevator.

Originally Posted by Crumpp

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

That's sort of true, but not completely. For a wing with washout, max turn performance might not occur until some portion of the inner part of the wing is stalled and the wing as a whole has reached CLmax.

W.

[TomcatViP]

Originally Posted by RAF74_Winger

For a wing with washout, max turn performance might not occur until some portion of the inner part of the wing is stalled and the wing as a whole has reached CLmax.

W.

only a minor portion

Regarding buffeting it is a highly unstable flight regime by def. Generally a localized buffeting zone is set artificially during the design phase to warn the pilot that is entering the stall flight regime.

The buffeting is caused by a major recirculation of flow above the wing. Thus being unstable by definition. The Lift force ad pitching moment oscillating around a certain value cause the "shaking". Aeroelasticity plays also its role here needing more washout to give a safety margin (and more drag) (see http://www.aerospaceweb.org/question/planes/q0099.shtml)

Winger , I can put my tail plane on top of a 10m pole above the fuselage and will still experience wing buffeting.

Regarding the F18 without going OT, if I wd hve been at Northrop I would hve design the buffeting point before the LERX vortex start to interact with the wings flow. A pilot would know then when he is entering high AoA flight regime. What I mean here is that the buffeting zone might be wider than in a conventional aircraft due to the interaction of conventional wing behavior and LERX.

http://www.aerospaceweb.org/question/planes/q0176.shtml

Regarding the Spitfire, the wider wing chord being rather flat (the max camber line being slightly frwd than conventional design), the pitchng moment is rather stable with AoA. This is good if you want to fit a variety of diverse equipment in a fighter aircraft but nasty when it comes to deal with a stall regime (IvanK that might give you some souvenir of teh Fr delta fighter spin )

In particular once such aircraft is committed in a spin, it is more stable here than an other aircraft with shorter wing chord and more rounded airfoil (there I wld like readers fans of RoF to think abt the barn door wing profiles of British WWI planes).

That said, it is mandatory to warm young pilots about the nasty behavior of such an aircraft in the spin. Then they will be more cautious in fight and the "turnability" of a Spitfire will vary greatly with the experience of its pilot.

That's all we said here as I can understand with Crumpp writing and I think this shld be in the sim (I was saying very much the same thing years ago with IL2).

Obviously an experienced fighter pilot will laugh of "the danger of being in a spin". But wait... Germans have shown the world twice that you don't win an air-war with experienced fighters pilots. That's all abt teh Legion Condor and the Hurricane, the experteen and the P51 or the WWI JastaCirkus and SPADs.


Note :
Writing this, I remember a Spit WWII WCO commenting the guncam footage of various pilots that were convinced they have hit their prey and demonstrating to them that they hve missed mostly because their plane were always drifting. This tells us a lot of how they were flying those planes that required much more attention than conventional aircraft when manoeuvring aggressively (of course not more than the early supersonics)

PS: it's a great discussion we hve here

[Crumpp]

Here is someone elese's view on this.

WEAK burble.....

Hardly the description of the Spitfire's very hard and pronounced buffet as related by the NACA and its effects on turning performance confirmed in the Spitfire Mk I notes.

[winny]

I just thought I'd give some historical perspective on this.

I've got lots of BoB RAF pilot's accounts, a recurring theme from the top pilot's is "riding the buffet" Geoff Wellum mentions it in 'First Light' And I've seen it repeated quite often.

Also, when the RAE were conducting the mock dogfights against a 109 they found that in every case where the 109 managed to get behind the Spitfire, it could stay there. when they looked at why, they found that the RAF pilot's were easing off when the buffeting started, when in fact they could have flown it on the edge and even tightened it slightly.

It fits with contemporary accounts from both sides, with plenty of cases of each out-turning the other. As is usually the case, the more familiar the pilot is with his plane the better the chances of survival were. Some flew it on the edge, some flew it as per the handbook.

[Crumpp]

Ok you are really off the plot in this response and thats just wrong.

I am not wrong and you even agree with what I said.

IvanK says:
you ease the back pressure off to get back into the Buzz .... Ideally the very first hint of it.

Ideally the very first hint of it...... No, Ideally you have none at all and are at the point just before any buffeting occurs. That is also what the Spitfire Mk I notes relate, crazy idea huh!

If you have no other way to determine that point, it works for practical purposes.

Gee, that is exactly what I have said!!

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

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.

Degree in aeronautical science....graduate type

Pilot......Aircraft Owner....several of them, they are great way to waste a lot of money!

Oh yeah, aerobatics too...

[Crumpp]

Some flew it on the edge, some flew it as per the handbook.

Umm there is no difference. The handbook tells you how to fly it to the edge...

What do you think the engineers are doing when they tell you those parameters??

Here is a secret....they are telling you how to get the maximum performance out of the aircraft, live to tell about it, and maybe be able to use the airplane on the next mission.

Mh. I think the pilots were taught to fly their planes after the handbook.

With experience and in battle they started to feel the plane and forgot about the handbook resulting perhaps in situations where they were closer to the edge than written in the handbook. One should remember that air behaviour depends on much more than just velocity and angle of attack. It may well depend on current temperature, roughness of the skin of the plane, winds and gusts, air humidity ...

[winny]

Originally Posted by Crumpp

Umm there is no difference. The handbook tells you how to fly it to the edge...

What do you think the engineers are doing when they tell you those parameters??

Here is a secret....they are telling you how to get the maximum performance out of the aircraft, live to tell about it, and maybe be able to use the airplane on the next mission.

What do you mean, no difference, it's the exact opposite.

You can argue with Geoff Wellum all you want. You said that the pilot's notes say to ease off when buffeting occurrs. Geoff Wellum, for one, didn't do this, and they weren't too concerned with the rule book or the maths of it either, they did what they had to to survive. I've also read of plenty of WEP abuse, bent airframes, bale outs when lost ( i.e. not bothered about using the airplane again)

I think the engineers were conservative in their pilot's notes.

[Crumpp]

What do you mean, no difference, it's the exact opposite.

Not even close. This is gaming fantasy and not the reality of flying aircraft.

I've also read of plenty of WEP abuse, bent airframes, bale outs when lost ( i.e. not bothered about using the airplane again)

Of course accidents happen and circumstances are not always ideal especially in combat. We get to hear the tails about the lucky ones who survived their experience. Unfortunately we cannot hear from the others who died because of exceeding the published limits.

Let's look at what the reality of operating aircraft has to say about the Pilot Operating Instructions:

The matching of the aerodynamic configuration with the powerplant is accomplished by the manufacturer to provide maximum performance at the specific design condition (e.g., range, endurance, and climb).

MMMM, maximum performance = follow the book

The use of this data in flying operations is
mandatory for safe and efficient operation.

Maximum Performance AND you get to stay alive!!

If you read this primer on Pilot Operating Instructions, you will find that for most maximum performance there is ONLY one point or airspeed that maximum performance can be obtained. That point is linked to the physical design of the aircraft and is given to the pilot by the engineers. There is nothing to be "conservative" about. Additionally, the margins are such there is very little room engineering wise to be "conservative" and still produce a machine that flys.

Read and enjoy!!

http://www.faa.gov/library/manuals/a...apter%2010.pdf

[winny]

Originally Posted by Crumpp

Not even close. This is gaming fantasy and not the reality of flying aircraft.

I can't put this any clearer. I'll leave it to someone who was there instead.

Geoff Wellum - " In a Spitfire, just before the stall, the whole aircraft judders, it's a stall warning, if you like. With practice and experience you can hold the plane on this judder in a very tight turn. You never actually stall the aircraft and you don't need to struggle to regain control because you never lose it. A 109 can't stay with you."

Time and time again people push machines past their operational limits, some live some die, that's not the point. The point is that 'riding the buffet' happened, for real. Geoff Wellum did it, as did many many other Battle of Britain pilots.

As for the reality of flying aircraft, what's your experience of flying Spitfires in combat?

I'll take my info from people who know what they are talking about, because they were there, thanks.

Originally Posted by Crumpp

MMMM, maximum performance = follow the book

You're sarcasm is palpable.

It's simply not the truth. I'll say it again, The RAE themselves (They conducted the 109 vs Spitfire mock dogfights) found that the reason in initial tests a Spitfire could not shake a 109 of it's tail was because the pilot's were backing off as soon as the buffet set in, when in fact it was possible to fly with the juddering and make a tighter turn. So max turning at least was achieved by not following 'the book'

Originally Posted by Crumpp

Maximum Performance AND you get to stay alive!!

No if you follow the book, you can't shake a 109, and you die.

Originally Posted by Crumpp

If you read this primer on Pilot Operating Instructions, you will find that for most maximum performance there is ONLY one point or airspeed that maximum performance can be obtained. That point is linked to the physical design of the aircraft and is given to the pilot by the engineers. There is nothing to be "conservative" about. Additionally, the margins are such there is very little room engineering wise to be "conservative" and still produce a machine that flys.

And what exactly has this got to do with combat flying? Irrelevant, they did whatever they could to stay alive.