Why do Spitfires turn better than Hurricanes?!

[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!

Originally Posted by TomcatViP

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

~S!

That was because of its tremendous weight ...

[TomcatViP]

Originally Posted by 41Sqn_Stormcrow

That was because of its tremendous weight ...

Note sure... Drop a 60lb girl and her 120lb father out of an airplane and watch what will happen... both will descend at a rather similar speed that depend only on their aero ratio. This is called the terminal velocity and the weight has little to do with it (humm now give them back their chutes or you will hve to tell me that that one had accumulated more E than the other )

But the initial acceleration is imparted, you are right.

By the way don't take me wrong guys... The Spitfire was a great airplane . It was only not the best one in terms of aero. Just like the 109 was one very refined design both in term of aero and structural design but a poor weapon for young conscripts with a low nbr of flying hour. Dozen hd to dye for the raise of one of the much vaunted experteen.

That's what I meant. That is as far as I have read why the FW190 could dive away to escape as it accelerated initially sufficiently well to have gone away.

[TomcatViP]

+1

We shld not forget that planes at those ages had a fairly low P/W ratio (power vs weight).

Hence once the weight component was added to the thrust line it multipliable the propulsive power

[lane]

Stephen Bungay has a chart of turning circles in his book "The Most Dangerous Enemy". It looks to me as if the turning circle at sea level for the Hurricane Mk I is about 660 feet versus about 690 feet for the Spitfire Mk I. (see attached) Great book, I highly recommend it!

I’ve been reading Group Captain Colin Gray's autobiography "Spitfire Patrol". There are some interesting passages related to this thread's topic. Another great book, I highly recommend this one too! Gray flew both Hurricane Mk I and Spitfire Mk 1 in combat and wrote:

"There have been many arguments about the relative merits of Spitfires and Hurricanes, particularly in relation to the mark 1 versions used in the Battle of Britain. As one who has flown both in action, I have no doubt that the Spitfire was superior by quite a margin. It was some 30 to 40 miles per hour faster, climbed quicker, and had a higher service ceiling. Being lighter on the elevators it was quicker and easier to manoeuvre, and contrary to general belief it could out-turn a Hurricane." (see attached)

"The problem of manoeuvrability was of prime importance in enabling one to turn inside the enemy, certainly in fighter versus fighter combats, and thus to get a shot in when on attack, or avoid being shot down when on the defensive – and here the British aircraft had a decided advantage in my experience." (see attached)

Though a bit off topic, though none the less of some interest, Gray also made a rather blanket statement regarding Spitfire and Me 109 turn, in this particular instance describing a Spitfire IX - Me 109 G2 combat which occurred in North Africa during April 1943.

"Just as I completed my turn I saw another aircraft coming towards me at high speed, as he flashed past I recognized a 109G2. He obviously recognized me as hostile because he immediately pulled up into a screaming left-hand turn and attempted to dogfight. This was his big mistake because there was no way a 109 could turn inside a Spitfire." (see attached)

Mr. Gray flew Spitfire Mks I, II, V, IX, XII and XIV in combat and is credited with 27.5 victories, all in Spitfires. He fought over Dunkirk and through the Battle of Britain in 1940; commanded a Spitfire IX squadron in North Africa, then was wing commander during the invasion of Sicily in 1943; and led a Spitfire XIV wing as Wing Commander Flying over France, Belgium, Holland and Germany in late 1944. He earned his say in my opinion and I’ll not be one to take issue with his experience.

The charts are interesting but not really helpfull. The turn radius is at what respective speed? Speed has an extremely strong impact on turn radius (turn around a corner while standing or while running you'll immediately sense the difference. For aircraft it is the same) and at which fill level. For me these are quite futile.

[bugmenot]

Originally Posted by lane

Stephen Bungay has a chart of turning circles in his book "The Most Dangerous Enemy". It looks to me as if the turning circle at sea level for the Hurricane Mk I is about 660 feet versus about 690 feet for the Spitfire Mk I. (see attached) Great book, I highly recommend it!

I’ve been reading Group Captain Colin Gray's autobiography "Spitfire Patrol". There are some interesting passages related to this thread's topic. Another great book, I highly recommend this one too! Gray flew both Hurricane Mk I and Spitfire Mk 1 in combat and wrote:

"There have been many arguments about the relative merits of Spitfires and Hurricanes, particularly in relation to the mark 1 versions used in the Battle of Britain. As one who has flown both in action, I have no doubt that the Spitfire was superior by quite a margin. It was some 30 to 40 miles per hour faster, climbed quicker, and had a higher service ceiling. Being lighter on the elevators it was quicker and easier to manoeuvre, and contrary to general belief it could out-turn a Hurricane." (see attached)

"The problem of manoeuvrability was of prime importance in enabling one to turn inside the enemy, certainly in fighter versus fighter combats, and thus to get a shot in when on attack, or avoid being shot down when on the defensive – and here the British aircraft had a decided advantage in my experience." (see attached)

Though a bit off topic, though none the less of some interest, Gray also made a rather blanket statement regarding Spitfire and Me 109 turn, in this particular instance describing a Spitfire IX - Me 109 G2 combat which occurred in North Africa during April 1943.

"Just as I completed my turn I saw another aircraft coming towards me at high speed, as he flashed past I recognized a 109G2. He obviously recognized me as hostile because he immediately pulled up into a screaming left-hand turn and attempted to dogfight. This was his big mistake because there was no way a 109 could turn inside a Spitfire." (see attached)

Mr. Gray flew Spitfire Mks I, II, V, IX, XII and XIV in combat and is credited with 27.5 victories, all in Spitfires. He fought over Dunkirk and through the Battle of Britain in 1940; commanded a Spitfire IX squadron in North Africa, then was wing commander during the invasion of Sicily in 1943; and led a Spitfire XIV wing as Wing Commander Flying over France, Belgium, Holland and Germany in late 1944. He earned his say in my opinion and I’ll not be one to take issue with his experience.

from the other side:

Herbert Kaiser, German fighter ace. 68 victories.
"Personally, I met RAF over Dunkirk. During this battle not a single Spitfire or Hurricane turned tighter than my plane. I found that the Bf 109 E was faster, possessed a higher rate of climb, but was somewhat less manouverable than the RAF fighters. Nevertheless, during the campaign, no Spitfire or Hurricane ever turned inside my plane, and after the war the RAF admitted the loss of 450 Hurricanes and Spitfires during the Battle of France." In the desert there were only a few Spitfires, and we were afraid of those because of their reputation from the Battle of Britain. But after we shot a couple of them down, our confusion was gone."


Erwin Leykauf, German fighter pilot, 33 victories.
"During what was later called the 'Battle of Britain', we flew the Messerschmitt Bf109E. The essential difference from the Spitfire Mark I flown at that time by the RAF was that the Spitfire was less manoeuvrable in the rolling plane. With its shorter wings (2 metres less wingspan) and its square-tipped wings, the Bf 109 was more manoeuvrable and slightly faster. (It is of interest that the English later on clipped the wings of the Spitfire.)
For us, the more experienced pilots, real manoeuvring only started when the slats were out. For this reason it is possible to find pilots from that period (1940) who will tell you that the Spitfire turned better than the Bf 109. That is not true. I myself had many dogfights with Spitfires and I could always out-turn them. This is how I shot down six of them."


Walter Wolfrum, German fighter ace. 137 victories.
"Unexperienced pilots hesitated to turn tight, bacause the plane shook violently when the slats deployed. I realised, though, that because of the slats the plane's stalling characteristics were much better than in comparable Allied planes that I got to fly. Even though you may doubt it, I knew the Bf109 could manouver better in turnfight than LaGG, Yak or even Spitfire."




LE-slats:


The German test pilot in this case was as vary about the slats as the British test pilots were when they flew it.
The problems only occured in tight turns though, and not in a slow speed straight stall, in which the slats on the Emil worked very well. The stall speed of the Emil is 61 mph flaps & gear down and 75 mph clean gear & flaps up.
All the problems with the slats were addressed with the introduction of the F series, and from there on the Bf-109 could & did comfortably engage in turning fights with the more maneuverable opponents.
The gentle stall and good control under g are of some importance, as they enable the pilot to get the most out of the aircraft in a circling dog-fight by flying very near the stall. As mentioned in section 5.1, the Me.109 pilot succeeded in keeping on the tail of the Spitfire in many cases, despite the latter aircraft's superior turning performance, because a number of then Spitfire pilots failed to tighten up the turn sufficiently. If the stick is pulled back too far on the Spitfire in a tight turn, the aircraft may stall rather violently, flick over on to its back, and spin. Knowledge of this undoubtedly deters the pilot from tightening his turn when being chased, particularly if he is not very experienced.

Messerschmitt Me. 109 Handling and Manoeuvrability Tests BY M. B. MORGAN, M.A. and D. E. MORRIS, B.SC.

Originally Posted by lane

Stephen Bungay has a chart of turning circles in his book "The Most Dangerous Enemy". It looks to me as if the turning circle at sea level for the Hurricane Mk I is about 660 feet versus about 690 feet for the Spitfire Mk I. (see attached) Great book, I highly recommend it!

It is a great book but the graph that you refer to has to be taken with care. As Bungay explains a friend of him who is working as an aeronautical engineer has calculated them - in a simplified manner as far as I understood. Being an aeronautical engineer myself my strong guess goes to that the friend of Mr. Bungay used some simplistic considerations, derived from these some very simplified equations and then put in numbers leading to the results depicted in the diagramm. For some basic estimations this approach is quite all right and acceptable but a good engineer should always (ALWAYS) be aware that this approach is far from reality. It may give some hints in terms of relative behaviour but honestly from my experience a difference of 10% between two airplanes will not say that one plane turns 10% tighter with this kind of approach. In fact they have to be considered practically equal or better a 10% with simplistic calculation is not significantly enough to make a statement. Now if the difference would have been 50% then one could with some confidence say that one plane turns better than the others although one still cannot say by how much one plane turns better. There are far too much uncertainties in this kind of engineering approach to believe in their results like some do in the words of The Book.

[Viper2000]

The original design for what became the Spitfire had straight taper. The elliptical planform happened because the man from the ministry kept demanding more guns.

There wasn't enough depth to accommodate them. The two options were to increase chord outboard or to increase t/c. Mitchell was a clever man, so he opted for the former.

However, the subtext of this was that he didn't anticipate a production run of 20,000+, mostly built in shadow factories.

He thought that Supermarine would probably make a few hundred at most, and therefore the extra work entailed in a nightmare of compound curves was quite a neat way of making work to keep his company in business.

I suspect that had he not died before his time, the Spitfire would probably have been rapidly been replaced by a more practical follow-on aeroplane with straight taper, or perhaps polytaper; though perhaps more interesting still is the possibility that fighter work might have been entirely handed to Hawker so that Supermarine could concentrate on their bomber, which was effectively a 4 engined heavy with Mosquito speed...

Meanwhile the P-47 was very fast going downhill, but had quite a low tactical Mach number, and was also rather a nightmare to manage due to the extra workload and failuremodes inherent in the turbo.