Interceptor vs Escort.

[FLYBOYJ]

Originally Posted by Soren

The P-51 was explained by its pilots as a pilots airplane, BUT, get into a stall with it "And your in deeeeep trouble !". The P-51's stalls were some of the most vicious of any fighter in WW2. (In the P-51's pilot's flight manual this is highly warned about)

The 109 on the other hand had a VERY forgiving stall, and it took 'much' longer to reach the stalling point aswell.

The Spit stalled better than both the -109 and -51.

[Soren]

Originally Posted by FLYBOYJ

The Spit stalled better than both the -109 and -51.

British fairytale

The slats on the 109 made it much more forgiving in the stall than the Spitfire.

However the Spitfire did have good stall characteristics nontheless, because of the 2 degree twist (washout) of the wing tips that was needed for at least partially taming the nasty and violent stall behaviour of the elliptcal shape wing.

So the truth is that the Bf-109 had much better stall characteristics than the Spitfire.

[FLYBOYJ]

Originally Posted by Soren

British fairytale

The slats on the 109 made it much more forgiving in the stall than the Spitfire.

However the Spitfire did have good stall characteristics nontheless, because of the 2 degree twist (washout) of the wing tips that was needed for at least partially taming the nasty and violent stall behaviour of the elliptcal shape wing.

So the truth is that the Bf-109 had much better stall characteristics than the Spitfire.

Don't think so Soren - An Elliptical wing will ALWAYS give great advanced stall warning characteristcs. The Stall starts at the wing tips and moves inboard - exactly what is desired in any aircraft! 3/4 of good stall characteristics is knowing when the stall is going to happen. The other 1/4 is knowing what the aircraft is going to do when it does stalls.

[Soren]

Originally Posted by FLYBOYJ

Don't think so Soren - An Elliptical wing will ALWAYS give great advanced stall warning characteristcs. The Stall starts at the wing tips and moves inboard - exactly what is desired in any aircraft!

This is what was "Assumed" during the development of the elliptical wing, but sadly it was infact just theoretical, in reality it gave no difference. Besides automatic-slats has a much better effect on stall characteristics than a elliptical planform.

The elliptical planform has a very small theoretical advantage, but only theoretical, and only valid if the planform is truely elliptical. Spitfire's planform is only approximating elliptical, and what is left has been sold out by the aerodynamic twist it's wing has.
It has effect on just one of several factors of wing efficiency, causing a whopping 0.05 improvement in comparison to a trapezoidal planform used in for example Bf 109, that is, IF Spit's wing were truely elliptical...
You also have to take into account the fact that the profile thicknes ratio of Spit's wing is VERY thin, both in maximum and in average. This in turn leads to the small coefficient of lift. This pretty much takes away the advantage of the large wing area.
BTW, ever wondered where did all the elliptical wings go? If they are so magically efficient, why nobody uses them anymore?
The answer is simple, later aerodynamic research has proven that most of the benefits of elliptical wing were a fallacy created by insufficient or faulty research methods. They simply were not worth the trouble.
Even the developements of Spitfire, Spiteful and Seafang gave up on the elliptic planform and went to normal trapezoid form. Wonder why?
Only thing special in it is the elliptic planform, that dropped of favour just after it, when it was found out that the theoretical benefits of an elliptic planform were actually only theoretical, and practical applications did not yield benefits that would justify the almost astronomical manufacturing difficulties and costs.
In the Spitfire's case the benefits of elliptic planform (even lift distribution along the span) are nullified by the 2 degree twist (washout) that was needed for at least partially taming the nasty and violent stall behaviour of such wing.

Besides, wing aspect ratio has a much larger effect on the lift/drag characteristics than the Oswald efficiency factor (where the theoretical difference between Spit's and Bf 109's wing is only of magnitude of 0.05), and Bf 109's wing has higher aspect ratio than Spit's...

[FLYBOYJ]

I'm going to agree to disagree - PPL 101 - its actually a test question. An elliptical wing will give the best stall warning. Once in the stall, what prevents the spin? Application of rudder!

I'll Repeat - The Stall starts at the wing tips and moves inboard - exactly what is desired in any aircraft! 3/4 of good stall characteristics is knowing when the stall is going to happen. The other 1/4 is knowing what the aircraft is going to do when it does stalls.

The elliptical wing does this well.

[DAVIDICUS]

I recall that the USAAF tested the FW-190 against the P-47 in 1943 and one of the noted characteristics of the Fw-190 was its extremely bad high speed stall that was particularly dangerous because the aircraft exhibited no advance warning.

The P-47's wing shape may have had something to do with its ability to transmit an advanced warning.

The relevance here, if any, is that the P-47's wing shape was closer to the Spitfires whereas the FW-190's was closer to the ME-109's.

[FLYBOYJ]

Originally Posted by DAVIDICUS

I recall that the USAAF tested the FW-190 against the P-47 in 1943 and one of the noted characteristics of the Fw-190 was its extremely bad high speed stall that was particularly dangerous because the aircraft exhibited no advance warning.

The P-47's wing shape may have had something to do with its ability to transmit an advanced warning.

The relevance here, if any, is that the P-47's wing shape was closer to the Spitfires whereas the FW-190's was closer to the ME-109's.

Even though the -109 had LE slats it doesn't mean the stall warning will be pronounced unless you see or feel them deployed. Power setting and pitch angle will determing how the aircraft will "break" at the stall. High power, lots of torque, at the break one wing will drop. Without opposite rudder the aircraft will spin.

I suspect the -109, because of its slats will not allow the wing to drop as quickly. During stall recovery the Rudder, elevators and aileron gain effectivness in that order.

[wmaxt]

Originally Posted by FLYBOYJ

I'm going to agree to disagree - PPL 101 - its actually a test question. An elliptical wing will give the best stall warning. Once in the stall, what prevents the spin? Application of rudder!

I'll Repeat - The Stall starts at the wing tips and moves inboard - exactly what is desired in any aircraft! 3/4 of good stall characteristics is knowing when the stall is going to happen. The other 1/4 is knowing what the aircraft is going to do when it does stalls.

The elliptical wing does this well.

I agree with you Flyboy The Spit had the best stall of the single engine aircraft.

I also agree the P-51 had a terribly accelerated stall requiring a 10k minimum to recover according to the manual.

I also agree the later P-38, Spit and P-47s were the best Allied Fighters.

As I posted yesterday testing opposing aircraft always includes some bias be it experiance in the other aircraft, condition of the aircraft or something else that may be unknown. The truth, like it or not, is that the tests are still as honest as the pilots can make them.
1. Intentionaly biasing the tests, endangers the pilots the information is passed to. They need the correct info to allow them to counter the enemy and live.
2. It would prevent incorporating advances in there own aircraft.
3. If caught intentionaly ruining the results of a test like that your reputation would be destroyed maybe your career to.

They may not be perfect but but to say they mean nothing or are completely wrong is just delousion. At a minimum they represent the perceptions of a pilot with low time in that type of aircraft. Considering the training/replcement issues the Germans had to deal with in '44/'45 those tests may be even more appropriate than they would otherwise.

wmaxt

[DAVIDICUS]

I was actually making a comment concerning your statement that, "An Elliptical wing will ALWAYS give great advanced stall warning characteristcs."

The P-47 had no poor stall warning characteristics. It's wing is pseudo-elliptical. The Me-109 had poor stall warning. So did the Fw-190. Their wings were similarly geometrically shaped.

[Soren]

Originally Posted by FLYBOYJ

I'm going to agree to disagree - PPL 101 - its actually a test question. An elliptical wing will give the best stall warning. Once in the stall, what prevents the spin? Application of rudder!

.

But the Spitfire's wing wasnt elliptical, as the Spitfire's wing had approxmiately 2 degrees of twist, so the lift distribution was
not elliptical.

I'll Repeat - The Stall starts at the wing tips and moves inboard - exactly what is desired in any aircraft! 3/4 of good stall characteristics is knowing when the stall is going to happen. The other 1/4 is knowing what the aircraft is going to do when it does stalls.

Note where slats are located on the wing

The slats are in the area where air is accelerated, thus the air won´t separate as easily as on a wing without slats.

The elliptical wing does this well

Yes a whopping 0.05 times better than a ordinary trapezoidal wing, but still only "theoreticly". (Not much )

Slats have a immensely greater effect on stall characteristics than a elliptical planform ! When deployed the Slats increased the wings CL-max and max AoA by a whole 25% !

Even Wing Aspect ratio has a much greater effect than a elliptical planform.

In any case the Spitfire's wing actually wasnt elliptical, so the Microscopic benefits of such a wing actually weren't present with the Spitfire.

[Soren]

Originally Posted by DAVIDICUS

I recall that the USAAF tested the FW-190 against the P-47 in 1943 and one of the noted characteristics of the Fw-190 was its extremely bad high speed stall that was particularly dangerous because the aircraft exhibited no advance warning.

The P-47's wing shape may have had something to do with its ability to transmit an advanced warning.

The relevance here, if any, is that the P-47's wing shape was closer to the Spitfires whereas the FW-190's was closer to the ME-109's.

A Fw-190 doesnt have slats

[FLYBOYJ]

Originally Posted by Soren

Yes a whopping 0.05 times better than a ordinary trapezoidal wing, but still only "theoretical". (Not much ) .

On paper it doesn't seem much - I'm willing to bet dollars to donuts that 0.05 will make a differance at the end of the stick!

Originally Posted by Soren

Slats have a immensely greater effect on stall characteristics than a elliptical planform ! When deployed the Slats increased the wings CL-max and max AoA by a whole 25% ! .

And I agree

Originally Posted by Soren

Even Wing Aspect ratio has a much greater effect than a elliptical wing.

Not during stall warning!

Originally Posted by Soren

In any case the Spitfire's wing actually wasnt elliptical, so the Microscopic benefits of such a wing actually weren't present with the Spitfire.

If it looks like a duck, acts like a duck.....

As I said before: 3/4 of good stall characteristics is knowing when the stall is going to happen. The other 1/4 is knowing what the aircraft is going to do when it does stall.

[DAVIDICUS]

Originally Posted by Soren

A Fw-190 doesnt have slats

I was just commenting on wing shapes and the relationship to advanced stall warning.

FLYBOYJ said, "An Elliptical wing will ALWAYS give great advanced stall warning characteristcs."

[ricardo]

Originally Posted by Soren

Oh no, not those British tests again...

Remember, the British hardly dared to fly the plane.

Consequently, British tests with the 109 are worthless...

I'm agree with you Soren.... but that's not all... that captured Bf109G, that the British tested against their Spitfire Mk XIV, was not a pure fighter...it was actually a Bf109G-6/U2 (which carries underwing 20mm cannons). We all know that it is not a 100% objective test as those underwing OVERWEIGHT reduces performance. I saw an image of that captured fighter and what I can tell you is that it looks like a Bf109G-14 with 20mm gondolas under each wing.

Check this out:
http://1000aircraftphotos.com/Contri...Simms/3600.htm

[FLYBOYJ]

Soren, I will agree with you in as much as the Elliptical did disappear for awhile, it is hard to manufacture. The last aircraft I could think of to use this wing was the Culver Cadet, a trainer (You think you might want good stall warning on a trainer?). I've seen many kit planes starting to use elliptical wings as carbon fiber construction makes building this wing a lot easier over wood or aluminum.