Spitfire vs Me109. Sustained Turn

Great post Galdri 🙂

Moggy

Seconded (thirded?)

Much clearer on the issue of 109 slats now. Any chance you could come and help me with this article on forensic computing??

The old ‘my widgets better than your widget’ argument.

I’d disagree (nicely, of course) 😉 . Technical supiriority is indeed there, but it’s the most minor factor among many others.

Study of air combat proves again and again that unless one type is completely outclassed (and we are talking biplane vs monoplane levels of difference, not minor degrees) pilot capability (skill, experience, training, fitness and morale etc) is always more important that 5% technical aircraft advantage, which the Spitfire and 109 exchanged as an ‘edge’ through the war, IMHO.

So if you compare contemporary versions of Spitfires and 109s through W.W.II one might have a technical advantage, but tactical situation and pilot capability always had a greater influence on combat results.

For the best qualified and quantified analysis on performance I think you’d do best to see Eric ‘Winkle’ Brown’s work. Certainly he evaluated late 109s and a selection of Spitfires and Seafires in wartime configuration for combat testing. Perhaps start with his ‘Testing for Combat’?

HTH.

As we used to say in the army ‘It’s not the equipment that matters so much as the person using it’.

Thanks for some good information! Galdri

Great post Galdri 🙂

Moggy

Wow this is a great thread…Really…

A mate of mine is a Spitfire veteran,Sicilly,Italy and Burma and he has been in combat and been fired upon.Last thing you worry about is your plane falling apart.You will push it and yourself to the absalute limits and quite often over it to stay “alive”.Flying Hf MkIX,s in Burma he and a few others came back from there first sorties with the Spits with wrinkled wing skins due to pulling out of dives against Japanese planes.As they say…”everything in the left hand corner”…

Correct me if I’m wrong but as far as I’m aware the slats were primarily an anti-spin device rather than a tool for reducing the stalling speed

Slats are not an anti-spin device. Spinning is perfectly possible in an aircraft fitted with slats. Spinning is the end resault when a wing excceds its max angle of attack, and a yaw is present. Of course it possible to exceed the max angle of attack of a wing with slats fitted.

It´s some ten years now since I was instructing, so bear with me, I´m out of practice:eek: 😀

In laymans terms, angle of attack is the angle at which the air hits a wing realtive to a line drawn from the absolute leading edge of a wing to the trailing edge (the longest line possible to draw between the two) and this is call the Chord line. So the angle between the Chord line and the oncomming air is called Angle of Attack. Most light aircraft, with none symetrical wings, typically fly with about 4° angle of attack in stable, level, flight. But that will depend on the all up weight of the aircraft. As you increase the angle of attack, the wings capabilities to produce lift will increase. But as you increase the angle of attack, the oncomming air will have ever harder time passing over the wing as it is forming a great obsticle in its way. The air will have less and less ability to pass smoothly over the top of the wing, rather it becomes detached from it, and will form a turbulent eddie current over the top surface that will not produce lift. As normal wing profiles (for the experts on here, I´m not muddling the water with the flat plate effect or the delta) require smooth air over the top to produce lift, this is not good news. So what is really happening, is that you are increasing the amount of lift generated by the wing, but at the same time, you are destoying the wings capability to produce lift:eek: All of this comes head to head at a point called the stall. At that point, you reach the optimum trade off between angle of attack and the damaging effects of eddie currents over the wing. Normal light aircraft wing stalls somewhere between 12°-15° angle of attack, depending on airfoil. Any more angle of attack, and the damaging effects of the eddie currents will cancel out the lift increase generated by increased angle of attack, and lift will actually decrease, the aircraft will not be able to maintain altitude, and, depending on airfoil, might become downright nasty to it´s passenger at that time:eek:

As you might have seen, I´ve never talked about stall speed. That is because wings do not stall because of speed. They only stall because of to large angle of attack! They great myth about the stall speed only comes from the fact, that angle of attack indicators are not installed in normal aeroplanes. This is how the infamous stall speed is found out. You take an aircraft up to altitude and close the throttle. As the speed decreases, the wings ability to produce lift decreases, so if you maintain a set altitude the angle of attack will have to incease to maintain the lift. At the time the aircraft stalls, you take a note of what the airspeed indicator is showing, and that will be you stalling speed from now on. It has nothing to do with the speed it self, but rather the optimum trade of between lift generation and eddie currents. That speed you read out at that time is only relevant to that weight of the aircraft. If you increase the weight, the speed shown will be higher, if you decrease it, the speed shown will be lower. Most of us know what g is, but if someone does not know, it is the force of gravity. As you are sitting in the chair in front of the computer you are experiencing 1g. At 2g you will feel 2 times as heavy as now. The same applies to aircraft. In a 2g turn, a 1000 Ibs aircraft feels like it is 2000 Ibs. And that affects the stall speed. It will go up by the root of the g. So an aircraft that has a publiced stall speed of 60 will stall at 84. Angle of attack will remain the same!

Now for the slats. Basically what they are, is a device fitted to the front of leading edge arranged in such a way, as to re-energize the air passing over the wing close to critical angle of attack. In normal flight, they have no function at all (except, if they are fixed, they will produce drag). Once the airfoil approaches the critical angle of attack, the air will start to pass between opening of the slat and the wing, and in doing so, it will speed up somewhat and the slat is shaped in a way to redirect the flow over the top of the airfoil. That will re-energize the air over the top, and help delay the onset of eddie currents. That will in turn help the wing produce more lift for a given angle of attack. Slat design vary, and the airfoil-slat combination will to, but let´s give an example of an airfoil that will reach it critical angle of attack of 14° without slats. With slats, that same airfoil will reach 18°. So if you want high angle of attack (slow speed, STOL) capability, you will be looking at slats to help you achive that goal.

The slats on the 109 are not there for slow speed operation, as in STOL operation. They are there for a very different reason, that is contolability. The wing profile seen on the 109, has the rather irritating habit of starting the stall at the wing tip, working it´s way gradually inwards with increased angle of attack. That will mean, that you will be loosing aileron control, before you really knew you were in a stall, and loosing a vital control is not good. There are three ways around this problem on a wing of that particular profile. You can build a wash-in into the wing. It basically means that you twist the wing, making that leading edge of the wing droop down (decrease the angle of attack) as you go out the wing. That basically means, that you will not be getting the most efficent wing possible as the outer portions are not developping the lift they could. Second line of attack would be to fit so called stall strips the the leading edge of the inner wing panels. What they do, is to create a turbulent airflow over the top at high angle of attack, fooling the wing into believing it is stalled when it really is not. That will degrade the lift production of the wing, not really what you want in a turning fight at high angle of attack! The germans chose the best thing. A slat covering the span of the ailerons, more or less. That way they hoped to get re-energized air over a portion of the wing that was stalled in relation to the rest of the wing, hoping to maintain aileron control (and lift on that protion of the wing) all the way to a complete stall of all the wing. It works very well. BUT, and there is always a BUT!

The slats on both wings are not interconnected, so one will open irrespective of what the other is doing. In the perfect world, you will be in a totally co-ordinated turn and both slats would open automatically together with no hassel at all, you would hardly notice it! However, in the heat of a combat, I do not think you give a sh*t about the elegant way of flying. You just do what you think you have to do, co-ordinated, slipping or skidding, what ever it takes. And that is where this system will let you down. Picture this. You are in a 109 doing a turning dogfight to the left with a Spit, you have a lead on him in your sight, just about right! Well that was easy, I´m not even pulling as hard as I could, plenty left before stall. Hummm, lousy flying, he is actually loosing hight in the turn, what do they teach these guys in the RAF? In a tight turn how do you correct for that one? Well, you use bottom rudder, you ++++++++. You touch bottom rudder very gently with your feet………..all of a sudden the aircraft rolls sharply out of the turn, approaching wings level, with the Spit way out of the gun sight, and you are very alone. What happened was that as soon as you touched the bottom rudder, the left wing started to stall, the slat opened, and the sudden lift increase cought you out cold. The aircraft rolled to the right, and you lost that Spit.

Waiting for all the “experts” to shot me down in flames.

The problem with independant and ‘automatic’ slats is that the airflow over the left wing in a banked tight turn can be different to that of the right wing such that the slat may deploy only on one wing, and this, of itself can lead to a spin, besides any other problematic immediate manouveres.

If I recall correctly, clipped wing spits were produced to effectively tackle the ‘190 at low level.

I’m interested in the issue of the leading edge slats as used on the 109. The suggestion that an experienced pilot could use the slats to give a tighter turn at low speed is given in what appears to be a rather biased account in ‘Messerschmitt 109 at War’ and I’d like to see if there is anything to back it up.

It strikes me that this tactic would need a lot of skill as the slats were automatic and worked on negative air pressure, so as one wing was about to stall, the slat would pop out. As this happened unevenly you get the ‘bucking’ that John Dell referred to, and as the aircraft was so close to the stall would surely have needed a master to keep it on the knife-edge. As has been pointed out, because of the Spitfire’s washout, an inexperience pilot could quite easily hold the Spitfire on the cusp of a stall without danger.

Correct me if I’m wrong but as far as I’m aware the slats were primarily an anti-spin device rather than a tool for reducing the stalling speed as in, say, the Twin Pioneer or Storch where the operation of the slats can be controlled by the pilot.

The same account suggests (in contrast to the post immediately above) that the 109 had a superior roll rate to the Spitfire. I wonder which it is, or if it switches depending on speed? As far as I was aware the Spitfire’s roll rate was never that good, and it had heavy ailerons (hence the replacement with metal skinned ones and to an extent, the clipping of wings in some models)

Paul Day was shown demonstrating the back stick problems in the ME109 as compared with the Spit in a presentation I recall watching years ago. At the same time he indicated the view out of the Spit cockpit and said “but under that wonderful eliptical wing all manner of nastiness could be developing”.

That, I believe, was the Channel 4 “Equinox” special on the Spitfire – I have it on video someplace. Day was shown climbing into an unpainted Black 6 (the film was made while the ‘109 was still being restored) and also into Spitfire P7350.

“The rate of roll of the Messerschmitt was inferior to the Spitfire at high speed. Since you have to roll before you can get into a turn this gave the Spitfire pilot another advantage at the start of any turning dogfight at high speed.”

Another related factor was that the narrowness of the cockpit often meant that the control column couldn’t be moved far enough to give full aileron deflection without fouling the pilot’s legs, perticularly larger pilots or those wearing thicker clothing. I’ve seen this mentioned both in contemporary and modern pilots’ accounts of flying the type.

Paul Day was shown demonstrating the back stick problems in the ME109 as compared with the Spit in a presentation I recall watching years ago. At the same time he indicated the view out of the Spit cockpit and said “but under that wonderful eliptical wing all manner of nastiness could be developing”.

It’s hard to be exact on this as the two types were developed over a period of years so to say the Spitfire always outrolled the 109 is a moveable feast. However the results of the RAE testing the Spit 1 against the 109E are reproduced here:

http://www.spitfireperformance.com/spit1vrs109e.html

The RAE reported “At 400 m.p.h. the Me.109 pilot, pushing sideways with all his strength, can only apply 1/5 aileron, thereby banking 45 deg. in about 4 secs.; on the Spitfire also, only 1/5 aileron can be applied at 400 m.p.h., and again the time to bank is 45 deg. in 4 secs. Both aeroplanes thus have their rolling manoeuvrability at high speeds seriously curtailed by aileron heaviness.”

In both types the ailerons stiffened up notably with speed, the metal aileron mod on the Spit aiding this effect markedly as has been noted. The graph in this page does show the ME109 with an initial roll advantage but the Spit gains the upper hand once the speed reaches about 325mph. At speeds below 250 m.p.h, when the ailerons are light and very effective, the 109 can be rolled very quickly, but there is a strong tendency for the nose to fall in the final stages of the roll, and the stick must be moved well back in order to keep the nose up and as we know the 109 has a limited amount of backstick available which therefore could inhibit the use of the full roll performance.

On turning, the RAE noted: “The minimum radius of turn without height loss at 12,000 ft., full throttle, is calculated as 885 ft. on the Me 109 compared with 696 ft. on the Spitfire.” and that the corresponding time to turn through 360 deg is 25 seconds for the Me 109 and 19 seconds for the Spitfire.

The final words are those of the pilots and they all give credit to the 109 –

Deere: Overall there was little to choose between the two fighters.

Dundas: …the Messerschmitt 109 and the Spitfire were extraordinarily evenly matched…. But on balance the Spitfire was, I believe, slightly the better aircraft.

Galland: …the Spitfire, which although a little slower, was much more manueuverable…

According to Alfred Price’s “The Spitfire Story”, the Spitfire XIV easily out-turned the Bf109G in either direction, and rolled much more quickly. (This taken from the results of a tactical trial using an early production MkXIV (RB179) in February-March 1944).

Against the FW-190, however, the ‘190 rolled quicker.

LE slats

I’m interested in the issue of the leading edge slats as used on the 109. The suggestion that an experienced pilot could use the slats to give a tighter turn at low speed is given in what appears to be a rather biased account in ‘Messerschmitt 109 at War’ and I’d like to see if there is anything to back it up.

It strikes me that this tactic would need a lot of skill as the slats were automatic and worked on negative air pressure, so as one wing was about to stall, the slat would pop out. As this happened unevenly you get the ‘bucking’ that John Dell referred to, and as the aircraft was so close to the stall would surely have needed a master to keep it on the knife-edge. As has been pointed out, because of the Spitfire’s washout, an inexperience pilot could quite easily hold the Spitfire on the cusp of a stall without danger.

Correct me if I’m wrong but as far as I’m aware the slats were primarily an anti-spin device rather than a tool for reducing the stalling speed as in, say, the Twin Pioneer or Storch where the operation of the slats can be controlled by the pilot.

The same account suggests (in contrast to the post immediately above) that the 109 had a superior roll rate to the Spitfire. I wonder which it is, or if it switches depending on speed? As far as I was aware the Spitfire’s roll rate was never that good, and it had heavy ailerons (hence the replacement with metal skinned ones and to an extent, the clipping of wings in some models)

“The rate of roll of the Messerschmitt was inferior to the Spitfire at high speed. Since you have to roll before you can get into a turn this gave the Spitfire pilot another advantage at the start of any turning dogfight at high speed.”

Another related factor was that the narrowness of the cockpit often meant that the control column couldn’t be moved far enough to give full aileron deflection without fouling the pilot’s legs, perticularly larger pilots or those wearing thicker clothing. I’ve seen this mentioned both in contemporary and modern pilots’ accounts of flying the type.

Great post, WP. Very informative. 🙂

Ta! I was aware of the wash out effect on the Spit wing and have heard apocryphral tales of Spit pilots using it to entice 109s into a position where control of the latter was lost. That sounds a bit doubtful though I’m sure the ability to retain full controllability in a semi stalled condition was a great advantage.

Great post, WP. Very informative. 🙂

From http://freespace.virgin.net/john.dell/spitcom.htm:

MANOEUVRABILITY

A Spitfire pilot will tell you the Spit could turn inside the 109. Some Messerschmitt pilots were unshaken in their belief that the 109 could turn inside the Spitfire! Both designs were capable of turning circles that would cause the pilot to “black-out” as the blood drained from the head. The pilot who could force himself to the limits without losing consciousness would emerge the victor from a turning battle, and the Spitfire pilots had supreme faith in their machine. The British popular press (and even one broadcast by the BBC early in the war) told them that the wings came off the 109 in a dive or in tight turns, untrue but possibly based on some early wing failures in the 109’s predecessor the Bf108. British designers and aeronautical pundits also found the Bf109’s wing structure somewhat strange, with only two attachments between the wing and fuselage and their suspicions that this might prove fragile in combat probably influenced the popular press comments.

The Spitfire had a lower wing loading than the Bf 109 and this would normally give the better turning circle. However the 109 had help with its leading edge slots which gave a lower stalling speed, and thus was able to turn tighter than a simple comparison of wing areas might suggest. The 109 was very forgiving if stalled, with little tendency for a stall to develop into a spin, something that could happen to a Spitfire, although the Spitfire gave its pilot plenty of warning that he was approaching a stall due to the slight twist in the wing known as “wash-out”. It is this “wash-out” which probably holds the key to the Spitfire’s success. Because of the twist to the wings the stall (break up in airflow over the wing) would develop first near the fuselage rather than at the tip as on most conventional “straight” wings. This manifests itself as a feedback to the pilot through the controls and the airframe, in effect the Spitfire “talks” to the pilot and tells him he must ease back on the stick to avoid stalling completely. Because the airflow at the tips of the wings (where the control surfaces are) is still stable the controls are still effective. In a tight combat turn with minimum turning circle the aircraft is always on the edge of stalling, the feedback the Spitfire gave its pilot is probably the crucial factor in a turning battle.

There is more than one account by German wartime fighter pilots that suggest that many Luftwaffe novices did not use the turning performance of the 109 to the full. They seem to have regarded the point at which the automatic slots popped out as being a warning to ease back. Only more experienced pilots pushed the Bf109 to its limits. The way the slots operated could itself be a problem, causing the Bf109 to “buck” and throw off the aim of the Bf109 pilot, perhaps at the critical moment.

Both the Spitfire and Messerschmitt became harder to control at high speeds, with greater and greater strength needed on the control column as the speed increased.** However the problem was much worse in the Messerschmitt and in the high speed fights that developed in the Battle of Britain the Spitfire had the advantage.The Messerschmitt’s elevator control was very heavy at high speed and there are reports that Spitfire pilots would escape from 109s by diving towards the ground and pulling up at the last moment knowing that the German would find it much harder to pull back on the stick to escape destruction. The Spitfire was capable of being pulled out of a dive with such high “g” forces that the pilot would black out (for only a second or so), meaning the pilot, not the aircraft, was the limiting factor, this is how it should be for a fighter. The Messershmitt’s heavy elevator control at high speed meant that a German pilot would not be able to pull enough “g” to black out, meaning the aircraft itself was the limiting factor.

This brings us to the control column; the small cockpit of the Bf109 allowed only a very small area of travel for the stick, only 4 inches. Nowadays, with powered controls this would be seen as an advantage (like the small steering wheel in a racing car), but in 1940 pilots used sheer muscle-power to haul their aircraft around the sky. The cramped cockpit of the 109 meant that its pilot could employ only a fraction of his strength on the control column. Meanwhile the more spacious Spitfire allowed more elbow room for its pilot to wrestle with the control column, which was topped by a large spade type grip so that the pilot could use both hands.

The rate of roll of the Messerschmitt was inferior to the Spitfire at high speed. Since you have to roll before you can get into a turn this gave the Spitfire pilot another advantage at the start of any turning dogfight at high speed.

Thus it can be seen that if a Spitfire pilot could keep the speed of the dogfight high he held a distinct advantage in manoeuvrability.

Two very different appraisals of the turning circles of the Spitfire and Bf109 can be found in the books “Fighter” by Len Deighton and “The Most Dangerous Enemy” by Stephen Bungay. The former has a diagram showing the Bf109s turning circle to be inside that of the Spitfire (750 feet and 880 feet respectively) while the latter has a diagram showing the opposite (850 feet and 700 feet respectively). Crucially all the tests of mock combats between captured Bf109s and Spitfires always give the Spitfire the edge.

For the pilot answer, there is one who frequents this forum who has flown many Spitfires and a real 109…so over to him!!

And who will that be?

Thanks for answering my post.

First of all, I am not a pilot, just a humble Flight Test Engineer, so strictly speaking, am not qualified to answer your question as posed. However, handling reports and comparisons (using the same pilot) showed that the Spitfire had better sustained turn performance (i.e. turn rate keeping altitude and airspeed constant) could frequently out turn the 109.

Regarding instantaneous (i.e. max turn rate with speed bleed off), anecdotal evidence suggests that the Spit may have been more hardy and Luftwaffe pilots were not so keen to pull and pull……….however, you must remember that wartime aircraft did not have g meters. Test aircraft did.

Another poster suggested that it depends on the pilot, hence true comparisons could only be made with accurate parameter recording or popping the same pilot in both aircraft….but in reality it all came down to skill of pilot and how far he was willing to push the envelope. Put simply, how sweeter would Swan lake sound? Played on a Stradivarius Violin by me (i.e. with no musical talent whatsoever) or an expert playing a cheap chinese school violin?

For the pilot answer, there is one who frequents this forum who has flown many Spitfires and a real 109…so over to him!!

Treadstone,

You might want to check here:

http://www.spitfireperformance.com/spittest.html

I’m pretty sure that there is some turn rate comparison charts in the various Spitfire v’s 109 variants sections.

It truly is a great site, and now has a companion site called WWII Aircraft performance:

http://www.wwiiaircraftperformance.org/

Cheers

Paul

The old ‘my widgets better than your widget’ argument.

I know the pilot is a deciding factor , but generally i belive one aircraft is superior.

I’d disagree (nicely, of course) 😉 . Technical supiriority is indeed there, but it’s the most minor factor among many others.

Study of air combat proves again and again that unless one type is completely outclassed (and we are talking biplane vs monoplane levels of difference, not minor degrees) pilot capability (skill, experience, training, fitness and morale etc) is always more important that 5% technical aircraft advantage, which the Spitfire and 109 exchanged as an ‘edge’ through the war, IMHO.

So if you compare contemporary versions of Spitfires and 109s through W.W.II one might have a technical advantage, but tactical situation and pilot capability always had a greater influence on combat results.

For the best qualified and quantified analysis on performance I think you’d do best to see Eric ‘Winkle’ Brown’s work. Certainly he evaluated late 109s and a selection of Spitfires and Seafires in wartime configuration for combat testing. Perhaps start with his ‘Testing for Combat’?

HTH.

Do we have any resident 109 experten?

Treadstone … I started a thread some time ago about “an invitation to bomb London”
http://forum.keypublishing.co.uk/showthread.php?t=37243

That thread lead one of our esteemed members (M. AiB) to review Len Deighton’s book “Fighter” about the BoB. Generally the finding was that Deighton was on the money. Inter alia he (Deighton) asserts that German pilots were unwilling to test the limits of the 109 in tight turns due to their real or perceived fear regarding wing loading (ie, the bloody things might break) and in-turn handling related to the operation of the leading edge slats … read this post in that thread in particular:
http://forum.keypublishing.co.uk/showpost.php?p=594407&postcount=69

At the time I asked whether we had/have any 109 experten who could comment further. That request still stands !!!

Good luck in your quest, Don