Why do Spitfires turn better than Hurricanes?!

Walking to the wingtip without making move the plane (Mustang) is barely an indicator of the wing strength. I'd say it didn't move because the landing gear is set so much more apart from each other in a P51 than in a Spit that made the difference here.

One thing is fact which in turn is exploited today on purpose for modern fighter design but which also extends to other domains:

The less stable a device is the more prone is it to change its state. This principle can be exploited in a beneficial way. If you make something instable it is more easier to move around. For instance designs like the Eurofighter is instable and only kept on course because of computer software. This inherent instability allows to be more manoeuverable than a stable plane because anythings stable will tend to maintain its current status and is highly unwilling to assume another state (that is another attitude or flight direction).

So if the Spit is as manoeuverable it is likely on the edge of stability and thus somewhat nerveous.

[617Squadron]

^^^
This.

A lot of the veteran Spitfire pilot interviews have them talking about "strapping a Spitfire on and becoming part of the machine", however, they all comment that it wasn't an easy aircraft to fly for the inexperienced and it took a lot of hours to become fully proficient at throwing it around the sky.

More than a few Spitfires were written off or damaged as a result of poor landings by inexperienced pilots, usually wingtip stalls during or nose-ups after landing.

Let's not get into a peeing up the wall contest as to how much we each know about WW2 aircraft, eh? I'm beginning to think that I need a check shirt, a top pocket full of pens and glasses two inches thick to come on here....

[Sternjaeger II]

Originally Posted by 41Sqn_Stormcrow

Walking to the wingtip without making move the plane (Mustang) is barely an indicator of the wing strength. I'd say it didn't move because the landing gear is set so much more apart from each other in a P51 than in a Spit that made the difference here.

If you ever get a chance get to the wingtip of a Spit, rock its wing and see what happens, then do the same on a Mustang (if you can grab the tip that is, it's SO thick!). The whole impression you get from being around a Spitfire that it was designed with (mostly wrong) performance in mind, not with sturdiness as main concern.

One thing is fact which in turn is exploited today on purpose for modern fighter design but which also extends to other domains:

The less stable a device is the more prone is it to change its state. This principle can be exploited in a beneficial way. If you make something instable it is more easier to move around. For instance designs like the Eurofighter is instable and only kept on course because of computer software. This inherent instability allows to be more manoeuverable than a stable plane because anythings stable will tend to maintain its current status and is highly unwilling to assume another state (that is another attitude or flight direction).

So if the Spit is as manoeuverable it is likely on the edge of stability and thus somewhat nerveous.

that is true with designs which are designed to behave as such. The Spit wing was designed in a time when transonic and supersonic envelopes hadn't been fully explored yet, and its flexibility could prove fatal if stressed under sustained heavy G loads.

Some years ago I had the chance to speak to a gentleman who fought first with Macchi 202 and then with Bf109s for the Regia Aeronautica. He met Spitfires over Northern Africa and he said that in two separate occasions saw two Spits diving to chase Macchis only to lose controls under what seemed to be compressibility issues of the tail surfaces.

[TomcatViP]

Compressibility is not really affecting the tail surface (even if it does). In fact most comments on this phenomena are describing the formation of shocks waves on the wing surface that affect the pitching moment. The pitching moment is so great that the tail surface can't compensate for it... Hence the horrific impression to pull the stick without effect. The immediate solution is to lower the Mach number.

yeah yeah ... I know I am "marking" the wall myself here too but ... this thread is full of info for anyone (e.g : a reminder is a valid info)... Let's step fowrd pass that ugly wall

Note :
1. the Stuka's pilot impression is really good add.
2. Closterman's feelings abt the Spit as one of the top scoring ace of the ETO shld be taken into account more seriously. And even if it does not affect the Spitfire MkI it's an important point of view regarding the Spitfire capabilities vs vs the assumptions made here that tends to extrapolate perfs out from charts of latter variants.
3.the pitching moment is negative on most airfoil section

[Sternjaeger II]

Originally Posted by TomcatViP

Compressibility is not really affecting the tail surface (even if it does).

LOL I love you man

In fact most comments on this phenomena are describing the formation of shocks waves on the wing surface that affect the pitching moment. The pitching moment is so great that the tail surface can't compensate for it... Hence the horrific impression to pull the stick without effect. The immediate solution is to lower the Mach number.

yeah yeah ... I know I am "marking" the wall myself here too but ... this thread is full of info for anyone (e.g : a reminder is a valid info)... Let's step fowrd pass that ugly wall

I always dozed during my theory lessons, but if memory serves compressibility on tail surfaces is the creation of shock waves on the leading edge, which creates a void that makes the control surfaces ineffective because they're outside of the airstream (Viper might give a more educated explanation of it).

[TomcatViP]

Originally Posted by Sternjaeger II

LOL I love you man



I always dozed during my theory lessons, but if memory serves compressibility on tail surfaces is the creation of shock waves on the leading edge, which creates a void that makes the control surfaces ineffective because they're outside of the airstream (Viper might give a more educated explanation of it).

No no no..

The tail plane is affected too but this is not the primary prob. In fact it impact the transonic regime by raising the overall drag of the plane as a consequence of the mach shock on the wing itself - e.g : the compressibility - that alrdy affect the plane with a nose down torque.

the thiner is the wing (thickness/cord) , the latter does this occur due to overall smaller camber ratio.
The easiest solution found at the time was to use symmetrical wing section.

Once the wing mach shock wave has been addressed then the tail shock became a problem you are right (take a look to the X1 story)

~S

[617Squadron]

/Off topic

You are correct, and the Bell X-1 stole an idea from the British Miles M-52, an aircraft that Brown was sure would have exceeded Mach 1 and he was slated as the possible pilot for the prototype.

The M-52 had an 'all-moving' elevators that cured the problems that Bell had with the shock wave from the wing causing 'washout' of the X-1's elevators and loss of control as you neared Mach 1, a phenomenon that some WW2 pilots (P-38 Lightnings in particular) also experienced in sharp dives.

[Sternjaeger II]

Originally Posted by TomcatViP

No no no..

The tail plane is affected too but this is not the primary prob. In fact it impact the transonic regime by raising the overall drag of the plane as a consequence of the mach shock on the wing itself - e.g : the compressibility - that alrdy affect the plane with a nose down torque.

the thiner is the wing (thickness/cord) , the latter does this occur due to overall smaller camber ratio.
The easiest solution found at the time was to use symmetrical wing section.

Once the wing mach shock wave has been addressed then the tail shock became a problem you are right (take a look to the X1 story)

~S

I hate to insist on a topic that I'm not well prepared in, but I believe compressibility shows on your tail surface first simply because the surface itself is smaller than the wing one, and proportionally the control surface is bigger, so the transonic and supersonic effects happen there earlier. But then again I'm happy to be proven wrong..

In other news, from the much hated wikipedia:
"A similar problem affected some models of the Supermarine Spitfire. At high speeds the ailerons could apply more torque than the Spitfire's thin wings could handle, and the entire wing would twist in the opposite direction. This meant that the plane would roll in the direction opposite to that which the pilot intended, and led to a number of accidents. Earlier models weren't fast enough for this to be a problem, and so it wasn't noticed until later model Spitfires like the Mk.IX started to appear. This was mitigated by adding considerable torsional rigidity to the wings, and was wholly cured when the Mk.XIV was introduced."

[617Squadron]

I was watching an episode of the documentary 'Spitfire Ace' today and during the interviews with veteran WW2 Spitfire pilots, some of them said that they had the chance to fly both the Spitfire and Hurricane and their opinion, the early versions of the two aircraft didn't have much between them in terms of turn rates when it came to a dogfight. At higher speeds, the Spitfire was actually slower in terms of rate of turn, as the ailerons became heavier to use and the wing loading increased. The Hurricane's higher wing aspect ratio helped turn rates at higher speeds due to the increased lift created.

Some veterans on the programme did remark that the Spitfire was a lot easier to throw around the sky, as it was designed as a thoroughbred fighter By Reginald Mitchell, unlike the Hurricane, that was derived as a monoplane version of the Hawker Fury by Sidney Camm; in fact, the Hurricane was originally called the 'Fury Monoplane' until it was renamed the Hurricane. The Spitfire was originally called the 'Shrew', until somebody at the RAF renamed it after a nickname for one of his daughters. Not the most romantic name for a classic fighter....

The veteran pilots also remarked that the Hurricane was far more robust, could suffer more damage and keep flying and was a more stable gun platform, hence the reason it was sent after the bombers, although the numerical superiority of the Hurricane compared to the available Spitfires in 1940 also had a lot to do with it. The Spitfire was left to deal with the fighter escorts on more equal terms of numbers.

Here's a link to the series on Youtube, if you want to hear it for yourselves..... from people who were actually there and flew them....

http://www.youtube.com/watch?v=TQVnV0pm5TA

Episode 1, with links to the other episodes.....

[TomcatViP]

Originally Posted by Sternjaeger II

I hate to insist on a topic that I'm not well prepared in, but I believe compressibility shows on your tail surface first simply because the surface itself is smaller than the wing one, and proportionally the control surface is bigger, so the transonic and supersonic effects happen there earlier. But then again I'm happy to be proven wrong..

No problem. The ultimate fighter Pilot is the utmost finest Engineer (this is an awfully wrong statement )

Do you remember the Venturi effect when the air is accelerated through a narrower section ?
Now take a wider look at a wing section. If you focus either on the upper or the lower surface, you will see that regarding to the free stream of air unperturbed by the airfoil, there is a section increase as the thickness of the airfoil increase and the a similar decrease after the point of inflexion.

The direct effect of this (appart from the direct generation of LIFT) is that the air is accelerated and then as the section increased, expended with a rather brutal Pressure increase.

Now imagine that (I am actually singing it) you are flying at a speed nearly 2/3 of the speed of sound.

Due to the imaginary geometry described above, you can understand that the air is accelerated trough this partially materialized venturi. The increase in speed being directly proportional the the section decrease. Hence the more thickness the more the air flow is accelerated

When the speed and the wing's thickness are high enough, the airflow ard the wing reach Mach 1, the speed of sound. As the air goes further back along the chord, the air is expended (the distance btw the free airstram and the airfoil increase) and the air is decelerated bellow Mach one trough a pressure shock. This pressure shock is what we call a shock wave.

Now let say simply that due to he fact that the pressure distribution is modified because of both the shock waves above and bellow the wing, the LIFT moment is modified with a negative upward (relative to the chord) pitch down moment.
What you can see is that the more the wing is thick, the earlier the air ard the airfoil section reach the critical mach number.

Hence the thin airfoil series of the 50's fighters (Starfighter, F105, Mig 21 etc..).

This is why the compressibility affect the wing and not so much the generally thinner tail section.

Interestingly too this is what makes the Spitfire so fast in a dive. What you can see now is the sublime irony of mother nature that turned a wrong design assumption (the elliptical wing) in a wining parameter. I tell you Germany cldn't hve win !

Note : The 47 had an elliptical wing too. And it was also awfully fast in a dive!

~S!