Why do Spitfires turn better than Hurricanes?!

[reflected]

I had some fights online Hurri vs Spit. Spits can outturn Hurricanes without dropping a sweat, in a matter of seconds. Co E I mean. How come? Hurricanes should be a lot better turners, yet, it's like flying a bomber against Spitfires...This is absolutely crazy.

[Sven]

Which one has the correct turning time and which one doesnt? or are they both unrealistic?

[*Buzzsaw*]

Salute

Hurricane historically had a tighter turning circle than the Spitfire. However, the Spit retained energy much better, so that it could sustain a turn for a longer period. However, both should be able to easily outturn the 109 or 110, even the German reports noted that.

[ZaltysZ]

Hurricane historically had a tighter turning circle than the Spitfire.

And turn time?

[reflected]

Interesting question - which one seems off? 109 vs Hurricane seems to match historical reports whichever I fly, however, Spitfire vs anything else...

Don't get me wrong, it's my favorite plane, but I do like flying other machines too and something seems to be wrong here.

Somebody would need to do some proper tests because 1c won't do anything based on what I feel :P

[Kwiatek]

What i think Spitfire and Hurricane had quite similar sustained turn rate.

Spitfire had thiner wings ( lower lift cofficent) and was lower draggy plane with the same engine as Hurricane which had thicker ( higher lift cofficient) but with higher drag. Both had similar wingloading - so what i think and what i read both are very close.

[ZaltysZ]

I think Spitfire and Hurricane have pretty similar turn time, but Hurricane has its best time at lower speed (so, Hurricane has smaller turn radius, despite almost the same turn time as Spitfire).

[Viper2000]

It's not really very useful to say that aircraft x out turns aircraft y unless you specify the conditions more precisely.

For example, in IL2 I could quite easily out turn Spitfires with my Fw190; but only in certain (relatively small) parts of the envelope.

In the case of the Spitfire I and Hurricane I, they should have identical engines, and I think they should have identical props (though this isn't immediately obvious since their top speeds are sufficiently different that it might have been worth designing different props, especially in the early fixed pitch or 2 pitch days).

This means that altitude shouldn't be a major factor, because the engine power should be identical (apart from ram) at all altitudes. Note however that the cooling drag is obviously different, so if you're minded to lump this into the "engine" section of the drag & mass accountancy then YMMV (IMO this sort of distinction is academic until such time as we know how 1c have actually built the models, though I suspect that cooling drag will be part of the airframe model rather than the engine model).

I would expect the Spitfire to outperform the Hurricane in a constant energy turn at high speeds, simply because the Spitfire is faster.

I would expect the Hurricane to achieve a higher maximum turn rate and a tighter minimum turn radius than the Spitfire because its wing loading is lower.

I would also point out that both measures are academic unless you're crazy enough to stay in a turn fight for several complete circles, since otherwise differences in roll rate (and thus turn entry time) will be important; the Spitfire is likely to win here because its span is shorter and therefore it may be expected to have less roll damping, all else being equal (which I know it isn't before somebody starts).

Equally, very few real fights are going to take place at constant "total" specific energy (quote marks used because of course this fighter pilot's definition of total energy is only kinetic + gravitational potential). I would expect the Spitfire to have superior instantaneous turn performance because of its lower stick force per g and higher roll rate; so basically if you're going fast enough to have spare energy for an instantaneous turn, the Spitfire is likely to be able to dump energy into angles rather faster than the Hurricane.

IME, once one aeroplane in a fight starts to develop any kind of advantage, there is a tendency for the losing pilot to pull too hard in an attempt to catch up, which tends to actually make his position worse (because he's then fighting the other pilot's fight instead of his own).

Lots of people around here at the moment seem to pull too hard and get themselves deep on the wrong side of the excess power curve and then complain about the poor aircraft performance which results.

Finally, I would observe that the vast majority of pilots who lived to tell war stories spent very little time at the edges of the flight envelope, especially with regard to sustained turns. For this reason, the majority of accounts stating "Aircraft x clearly out turns aircraft y, because I did this numerous times in combat" are best taken with a pinch of salt.

Statistically, the sample is extremely biased, because dead men tell no tales.

Consider this scenario:

I want to find out whether or not it is safe to fly a kite in a thunderstorm.
I briefly review the literature, and find that Benjamin Franklin (http://en.wikipedia.org/wiki/Kite_experiment) did this successfully and wrote about it.


Is it therefore safe to fly a kite in a thunderstorm? Or was Benjamin Franklin simply a fairly lucky man? The Wikipedia page strongly suggests the latter, but it cites no sources in regard to its claim that:
The experiment also garnered attention and many attempted to recreate it. Some of the experimenters are known to have died during recreating the experiment.

I'm not suggesting that there are no references to be found on this subject - I'm just saying that one good "war story" told from the perspective of a "winner" is likely to assume more importance within the general literature than a secondary account of the experiences of those who gambled with their lives and lost.

So, you can find accounts saying that for example Spitfires would easily out turn 109s and you can equally find accounts saying that 109s could easily out turn Spitfires. What these accounts tell you is that the people who won fights tended to write more books about it than the people who lost them.

Genuinely satisfactory comparisons are extremely hard to come by. Genuine A/B comparisons under controlled conditions relied upon the use of captured aeroplanes which were inevitably less than representative of the average service machine (due to such factors as battle damage, lack of proper maintenance, incorrect fuel and lubricants, lack of proper batteries, lack of pilot experience, deliberate over-boosting to investigate development potential, questionable loadouts due to both lack of detailed knowledge and lack of suitable ordnance etc etc).

In fact, even when the aircraft being compared are fighting on the same side, it can be quite challenging to work out what was really going on; sometimes the manufacturer would "cheat" (e.g. Quill using a Spitfire XII in the race between Typhoon(?), Fw190A3 and Spitfire, making the political point that the Spitfire still had considerable development potential despite claims to the contrary from certain quarters perhaps not a million miles from Kingston). Sometimes you'd find that one pilot was better than the other. Sometimes you'd get a good example of aircraft x vs a bad example of aircraft y (the tolerances were pretty large even at the point of manufacture, and tended to grow in service as mods, wear and tear took their toll; or indeed as careful maintenance and clean-up work improved performance of certain special machines quite considerably - e.g. a few specialist high altitude Spitfires locally modified for extreme altitude performance to deter Ju86 overflights at FL400+).

So there's enough ambiguity for a thousand chart-wars.

IMO it is therefore much more sensible to attempt to match concrete aircraft performance data from original test data compiled for or by the intended end-user of the aeroplane, and to treat turn performance as an emergent behaviour.

If the other performance characteristics, which were defined and recorded in a considerably more satisfactory manner, are all matched, then it follows that the emergent turn performance is likely to be pretty accurate, because it's extremely unlikely that a good match across a number of known parameters (TAS vs altitude, stall speed, ROC vs altitude etc) would be dramatically wrong for unknown parameters (in other words, if I've got a car type, a colour, and a partial number plate, I am quite likely to have enough data to fill in the blanks because although there are lots of cars on the road, relatively few will pass through all of these "filters").

[deadmeat313]

Excellent post Viper2000!

However, we need to keep this debate going somehow, so errrr - I often find that my Hurricane barrel rolls much slower than I thought it would (based on a dream I had once with a Hurricane in it).

Fix pls Oleg! :P :)


T.

[Sven]

Well now that I think of it, in IL2 1946 4.10.1 spitfires also easily outturn hurricanes at any speed * ( As well as the newest M*d packs),
and that has been this way since the beginning as far as I remember (Forgotten Battles), not saying that that is what it should be, maybe time for revolution?;)

*Read for that underlined text: barely outturn it.

[Kwiatek]

Well now that I think of it, in IL2 1946 4.10.1 spitfires also easily outturn hurricanes at any speed ( As well as the newest M*d packs),
and that has been this way since the beginning as far as I remember (Forgotten Battles), not saying that that is what it should be, maybe time for revolution?;)

You havent tried Ultr@Pack 2.01? Haven't you?

Hurricane MK 1 +12 lbs is very close to SPitfire MK1 +12 lbs in UP if not little bit better at lower speeds

[Sven]

I find it very difficult in the Hurri to keep up with a Spit in UP 2.01, I mainly fly HSFX 5.0 now so my memory might be off.

EDIT: I just fired it up and can get them in a stable sharp turn and find the Spit to be quicker but it is indeed very close, but that's just feelings.
You are right though that when speed drops to 200 the spit has a harder time keeping up, and I have to let the elevator go a bit to prevent falling down to the earth, whilst the Hurri can push some what further.

[ATAG_Doc]

I am sure if we could go back in time and we were actually there and were all part of this, and we each had our plane we'd know what's up. What turns better and what is faster. What to do in a given situation. Because we have it at our disposal at any time we wanted to see and test. But this is a sim. There is and always will be differences based on the interpretations of a given developer.

[Viper2000]

I am sure if we could go back in time and we were actually there and were all part of this, and we each had our plane we'd know what's up. What turns better and what is faster. What to do in a given situation. Because we have it at our disposal at any time we wanted to see and test.

Not really. You'd get to fly the type of aeroplane you were given and for most people that would be it. So you might know quite a lot about for example the performance of the Hurricanes your squadron flew, but you wouldn't know very much about the performance of the Bf-109.

People would hear things on the grapevine. Some bits would be closer to the truth than others. Obviously a significant proportion of people who discovered the enemy's performance advantages didn't live to tell anybody about it...

During the Battle, quite a lot of RAF pilots said in their combat reports that they were fighting the He-113 (http://en.wikipedia.org/wiki/Heinkel_He_113) rather than the Bf-109. So much for "knowing" about the enemy's performance...

In fact, it was quite possible to fly a whole tour without seeing an enemy aeroplane at all, especially for Allied pilots later in the war. It's also worth observing that pilots who were trained during the war didn't necessarily get an awful lot of hours in which to experiment with the limits of aircraft performance, because the priority was operations rather than training. And the priority of operations was to attack ground targets and conduct reconnaissance. Fighters only exist to interfere with, or prevent interference with, the aeroplanes attempting to perform this useful work. AFAIK the average pilot in a WWII airforce was not a fighter pilot, though he might have told the girls otherwise.

Later in the war, more concerted efforts were made to convey the strengths & weaknesses of enemy aircraft to pilots, though of course this intelligence information was imperfect.

Since the best tactic to employ against an uncooperative enemy aircraft is entirely a question of relative performance, it follows that aerial combat was mostly a game of extremely high stakes poker.

For this reason, it was an extremely bad career move to actually get into the sort of fight whose outcome depended upon aircraft performance; the vast majority of aces scored their kills by exploiting their opponent's lack of SA and shooting them in the back rather than by getting into aerobatics contests with them.

Of course, if you score most of your kills by bouncing the enemy then you don't know or much care about the turn performance of his aeroplane; you care more about the operational habits of enemy pilots, such as the speeds, altitudes and types of formation in which they are inclined to cruise.

So even the best WWII fighter pilots probably knew considerably less about his opponents than the average sim pilot does.

A consequence of this is that sim pilots tend to make a bigger deal out of small performance differences.

If I feel inclined, I can spend a week or two testing the performance of all of the flyable aeroplanes in the sim. I can discover the 5% performance difference between aircraft x and aircraft y, and I can exploit that performance difference in combat with considerable confidence, leading to many forum posts about aircraft x's performance advantage over aircraft y.

IRL, production tolerances and pilot skill would render this sort of 5% performance difference entirely irrelevant; the absence of a refly button means that winning "most of the time" just doesn't cut it. Mixed reports of the outcome of turn fights would filter back to the squadrons, and the consensus would probably be that turn fighting was a bad idea in general, and an especially bad idea against aircraft y, because the success rate wasn't great.

It's very hard to get away from the fact that the massive psychological differences between fighting in a real war and playing with a flight simulator have a correspondingly massive impact upon the way that people fly, fight, and even think about their aeroplanes.

[bw_wolverine]

Very nice and thoughtful postings, Viper.

I find much more enjoyment with a combat flight sim playing it in the style of the real life encounters and events than trying to push the supposed accuracy of the simulation in general to my advantage or someone else's advantage. Because of that, minor differences or inaccuracies in aircraft performance tuning generally don't bother me, because you're right about the situations being about the pilot, his training, and what has happened in the past being much more an influence than his specific knowledge of just how far he can push his crate. (That said, I do like realism, and I wouldn't MIND if they tried to get it as accurate as possible, It's just not that big a factor in how much I enjoy the game itself).

I think we like to romanticize the actions of pilots a lot, and that's fine (we wouldn't be playing flight sims if we didn't!) but I think there's a reason that most war heroes and such say "I just did what I'm trained to do" etc. Circumstances beyond their control push their abilities, rather than them consciously trying to ride the bleeding edge.

[reflected]

I checked my books:

The Hurrican should have about the same turn time as the Spitfire, the 109 is worse.
However, the Hurricane should have a lot tighter turning circle than the Spitfire, the difference should be larger in this aspect than the one between the 109 and the Spit.

[Sternjaeger II]

I checked my books:

The Hurrican should have about the same turn time as the Spitfire, the 109 is worse.
However, the Hurricane should have a lot tighter turning circle than the Spitfire, the difference should be larger in this aspect than the one between the 109 and the Spit.

reflected, sorry but your absolute statements come out as somehow puerile..

you can't expect people to take you seriously if you say "I checked my books" without saying:
1) what books
2) the conditions of the turning tests (planes, conditions, altitudes etc..)

the whole matter of people coming on the forum saying "I've read it in a book" (and believe it or not, even books, which are written by men, can contain mistakes) and then wanting the developers to change the FM based on their personal preferences is just going to cause damage. It's not a personal attack, since you're not the only one that made such statements, but it's really annoying to read posts similar to yours on the long run.

In a nutshell, my suggestion is that people should get their facts right before making any statements or assumptions, if anything for the sake of the sim's accuracy.

[steppie]

first thing you have to remember they are different aircraft so don't think they have the same perform because the have the same power plant.(good example the spitfire and mustang had he same engine and propeller).

the Hurricane had a better rate of turn at a slower speeds than the spitfire but the faster the spitfire went the better it turn rate got over the hurricane.

But what is a fact they both out turned the bf109.

[6S.Manu]

But what is a fact they both out turned the bf109.
Yes but is it a fact that their turn times were more than 6 seconds better? :)

This is the real problem.

And anyway could really the Spit outturn the 109 at stall speed? (slats)

[reflected]

OK, I'm out of this discussion. I have many books, and all of them say the same thing, consistently. If I list them it won't change the facts. This is not the case in CoD. However, since I can't state that the sky is blue without reference I'll let you prove the opposite, I don't think 1C is gonna touch the FMs anyway.

No offense, but I'm not gonna write an essay, post charts and stuff jsut to convince you or prove that I'm right, because it will have no effect on the game (unless you're a dev, but you're not), so it would be a waste of time.

[ZaltysZ]

And it does not matter much what books say (and there is no need to list them), until some one does the flight tests in game. Sustained turn time at various speeds, that is. Until then, comparison of turns will be very subjective.

[Kwiatek]

Well after reading many books, real life test by RAF and LW also looking in technical data of both planes i think that the difference between both planes sustained turn rate wasnt such huge. Still Spitfire should have the edge both in slow and higher speed turn rate. Of course im sure that some more experience pilots in 109 could turn with Spitfires with unexperience pilot - it confirmed some German aces.

Slats in 109 help a lot in the egde of stall but we should note that slats in 109 not cover all leading edge area but mostly airleons area - which mean that you have more control when you are close to stall ( when your wing rot are actually in stall). Other hand Spitfire had washed wingtips which had similar effect - when your wing rots were in stall your wing tips are not and you have still control on airleons. Both planes had similar stall speeds but Spitfire had clearly lower wingloading.

Slats in 109 give it better stall characteristic so pilots could feel more safe in stall fights then unexperience pilots in Spitfires but other hand good pilot in SPitfire could quite easy fell incoming stall beacuse Spitfire wings give him plenty of warning.

So i think the difference wasnt such huge but still Spitfire should be better in turn.


BTW

Looking in 109 COD slats working i see that they open very late - at very low speeds and i think they should work much earlier.

I checked RAF 109 E test and slats should be open in level flight at 180-190 km/h. In COD they start to open at speeds below 150 km/h.

[palker4]

From my experience with hurricanes in 1946 you will always get outurned by faster aircraft. You have advantaqe at the beggining but if you fail to kill enemy plane you will loose energy and because lack of acceleration and worse climb rate you will lose in prolonged maneuver fights its not all about turn rate you know.

[Sternjaeger II]

OK, I'm out of this discussion. I have many books, and all of them say the same thing, consistently. If I list them it won't change the facts. This is not the case in CoD. However, since I can't state that the sky is blue without reference I'll let you prove the opposite, I don't think 1C is gonna touch the FMs anyway.

I have many books too, but it's not absolute academia that will give us answers. The turning performance of an aircraft is affected by many things:

1)aeroplane related: wing design, wing load, aeroplane weight, power plant, propeller, aerodynamic features.

2)environment related: mainly altitude (air humidity and temperature are negligible)

3)piloting related: pilot's general skill, pilot's specific skills on the machine, testing skills.

an aeroplane is like a short blanket: you can have an edge on something but it will affect something else.

The Spit had the edge in maneuverability because of the fantastic elliptical wing design, but it was an extremely flimsy and delicate wing structure which couldn't take much damage.



No offense, but I'm not gonna write an essay, post charts and stuff jsut to convince you or prove that I'm right, because it will have no effect on the game (unless you're a dev, but you're not), so it would be a waste of time.

..then what's the point of your original message? :rolleyes:
I am ready to hear any opinion and vouch for it or not, but it will need a thing called reliable evidences to support it.

[617Squadron]

There really wasn't that much performance difference between early models of Spifrire and Hurricane, but I don't think that sheer turning performance alone had that much to do with it.

Historically, in the early months of the BoB, the Hurricanes took on the bombers, as the airframe was more robust, it was a very stable gun platform, it could take more punishment and keep flying and the simple fact was that more Hurricanes were in service than Spitfires at that time.

Spitfires also tended to take on the fighter escorts more than the bombers, as Spitfires were considered the more agile fighter. The fighter escorts were also fewer than the bombers, so the odds were more evenly matched between the ME 109 and the Spitfire.

WW2 veteran Pilot interviews that I have watched about the Spitfire have commented that the ailerons were very heavy when compared to the Hurricane's, so there are other factors such as the brute strength of the pilot to consider. Heavy ailerons might make you think that turning rates would be slower as a result :confused:

In short, there is no right answer to this question, as there are so many factors at work.

[bugmenot]

And anyway could really the Spit outturn the 109 at stall speed? (slats)

Pierre Clostermann, Spitfire pilot.
"I tried to fire on a '109' that I spotted in the chaos. Not possible, I couldn't get the correct angle. My plane juddered on the edge of a stall. It was comforting that the Spitfire turned better than the '109'! Certainly at high speed - but not at low speed."

[TomcatViP]

Well after reading many books, real life test by RAF and LW also looking in technical data of both planes i think that the difference between both planes sustained turn rate wasnt such huge.



Good one


Still Spitfire should have the edge both in slow and higher speed turn rate.

High speed turn only. Without too much AoA (no high G). Their the Spitfire was uncatchable for the 109.

The Hurri turned even better and could be put in a descending high G spiral were nor the Spit or the 109 could catch him.

High G flat turn IMHO : the hurri would hve the advantage on the beginning but then would loose E quicker than the Bf due to it's poorer aero and P/W.

I know that some wld talk abt Wing loading and comparing P/WL ratio but this is relevant only with similar airfoils characteristics. You can't use this argument in such different design or you ended favoring the wide chord flat plate. Think abt the the WWI Focker high thickness wings and the cambered thin sections of both French and English design (ok ok I know RoF was completely porcked when they add in the Ninja Camel and SE's - don't refer to what you see there). The former could turn inside any allied design due to better LIFT generating devices - eg WINGS.



Slats in 109 help a lot in the egde of stall but we should note that slats in 109 not cover all leading edge area but mostly airleons area - which mean that you have more control when you are close to stall ( when your wing rot are actually in stall). Other hand Spitfire had washed wingtips which had similar effect - when your wing rots were in stall your wing tips are not and you have still control on airleons. Both planes had similar stall speeds but Spitfire had clearly lower wingloading.


You don't fly with your ailerons. The washing techniques only helps the pilot to ease the stall.
Furthermore, twisting the wing generate a huge extra amount of drag that hve to be compensated by extra power in such high drag situation of the slow turning fight. The 109 being cleaner, having a higher thicness ration (less AoA for the same lift) he has the edge here (but she might hve been harder to handle) .

Slats in 109 give it better stall characteristic so pilots could feel more safe in stall fights then unexperience pilots in Spitfires but other hand good pilot in SPitfire could quite easy fell incoming stall beacuse Spitfire wings give him plenty of warning.


+1



So i think the difference wasnt such huge but still Spitfire should be better in turn.


BTW

Looking in 109 COD slats working i see that they open very late - at very low speeds and i think they should work much earlier.

I checked RAF 109 E test and slats should be open in level flight at 180-190 km/h. In COD they start to open at speeds below 150 km/h.

[/QUOTE]

I do agree with you. The slats seems much too shy to pop out :rolleyes:

For those interested you can browse the War-Clouds forums where I remember we had some interesting discussions on that specific subject in the past

[TomcatViP]

Pierre Clostermann, Spitfire pilot.
"I tried to fire on a '109' that I spotted in the chaos. Not possible, I couldn't get the correct angle. My plane juddered on the edge of a stall. It was comforting that the Spitfire turned better than the '109'! Certainly at high speed - but not at low speed."

Cited in the "Great Show 2000". ;)

I don't remember reading this in the original "Great show" published in the 1940's

~S!

[BlackbusheFlyer]

There really wasn't that much performance difference between early models of Spifrire and Hurricane, but I don't think that sheer turning performance alone had that much to do with it.

Historically, in the early months of the BoB, the Hurricanes took on the bombers, as the airframe was more robust, it was a very stable gun platform, it could take more punishment and keep flying and the simple fact was that more Hurricanes were in service than Spitfires at that time.

Spitfires also tended to take on the fighter escorts more than the bombers, as Spitfires were considered the more agile fighter. The fighter escorts were also fewer than the bombers, so the odds were more evenly matched between the ME 109 and the Spitfire.

WW2 veteran Pilot interviews that I have watched about the Spitfire have commented that the ailerons were very heavy when compared to the Hurricane's, so there are other factors such as the brute strength of the pilot to consider. Heavy ailerons might make you think that turning rates would be slower as a result :confused:

In short, there is no right answer to this question, as there are so many factors at work.

Heavy ailerons affects rate of roll and has nothing to do with rate of turn. An aircraft described as having heavy ailerons means it is less agile for the pilot to change from one direction to another. The metal ailerons added to the Spits helped this problem.

You use aileron to establish the bank angle, then to turn you pull it with elevator. In combat turns it would mean steep turns greater than 60 degrees of bank (more like 90 degree turns pulling 2/3/4 G).

[TomcatViP]

Flat turn at :

60° of bank angle -> 2G
90° of bank angle -> 4G (min)

[BlackbusheFlyer]

Flat turn at :

60° of bank angle -> 2G
90° of bank angle -> 4G (min)

Correct

[Viper2000]

90º bank = descent

89.99999º bank = very large, but finite g required to maintain altitude without recourse to slip.

4 g is about 75.5º IIRC; vertical component of lift varies as the cosine of the bank angle, thus load factor required to maintain altitude is 1/cosine of the bank angle.

[TomcatViP]

90º bank = descent

89.99999º bank = very large, but finite g required to maintain altitude without recourse to slip.

4 g is about 75.5º IIRC; vertical component of lift varies as the cosine of the bank angle, thus load factor required to maintain altitude is 1/cosine of the bank angle.

he he but 75° was not in the input table Sir. Don't stamp me with a D
:)

[Viper2000]

The Spit had the edge in maneuverability because of the fantastic elliptical wing design, but it was an extremely flimsy and delicate wing structure which couldn't take much damage.

Sorry but this is simply incorrect.

There is an awful lot of rubbish written about the Spitfire's wing. It has a pretty elliptical planform, but it also has washout, so it doesn't have an elliptical lift distribution.

In fact, if you look at the early project drawings, you'll see that it started out with straight taper and four guns.

The elliptical planform came in when the Air Ministry decided that they wanted to increase the armament, first to 6 guns and then to 8; going to an elliptical planform provided the structural depth required to accommodate the extra guns outboard.

This is covered in some detail in Spitfire The History by Morgan & Shacklady (http://www.amazon.co.uk/Spitfire-History-Eric-B-Morgan/dp/0946219486) IIRC...

The real genius of Mitchell's wing design was that he realised that a low t/c would result in good high speed performance; the Spitfire had the highest tactical Mach number of any WWII fighter, and could not be out-dived by any aircraft under control until the advent of the XP-86 in 1947.

It certainly wasn't delicate: it had one of the highest limiting speeds of any WWII fighter; 450 mph EAS for the Merlin Spitfire's wing, and somewhat faster for the Griffon Spitfire (IIRC Henshaw states 520 mph; but this is probably IAS assuming about 20 mph position error; Henshaw dived Merlin Spitfires to 470 mph IAS routinely as part of their production testing, and from what I can gather this was because the position error was assumed to be 20 mph IAS at this speed). That's not what I'd call a flimsy wing.

Furthermore, we know that the absolute load factor that the Spitfire's wing could take was >>10 g; the RAE high speed flight had an unfortunate habit of breaking props & reduction gears away from their PR.XI Spitfires in high Mach number dives, with extensive instrumentation aboard, and rather impressive figures (c.12 IIRC) were recorded without structural failure (although the aeroplane was comprehensively bent and subsequently scrapped).

The main problem with the Spitfire's wing was that it was hard to build because it's a collection of compound curves. It was also uncomfortably thin for carrying the armament required. Naturally being hard to build, it was also hard to repair in case of battle damage.

But as for the amount of damage it could take, I haven't seen anything like as much gun camera footage of Spitfire wings being knocked off, even by cannon fire, as I have of other types. Of course, there's an obvious bias problem with guncamera footage, because there's relatively little German footage. But the Germans undoubtedly had big guns, so they'd arguably have more chance of dismantling aeroplanes for the camera than for example the Americans.

[TomcatViP]

Did I say that I luve yo ? :rolleyes: (quoting AB ;)) i am so glad to read you.

let's go a step behond if you don't mind :
The elliptical theory is a misunderstanding of a Math tools applied to aero. It does not hve a real bckgrd unless with biased assumptions.

The fact is (as stated by Vip above) that thickness ratio and the wonderful Merlin made the spit what it was as a real performer. And the all genie of R. Mitchell was to build the Spit as a weapon platform that any average pilot could use and perform where German's Nazi kept arguing with their elitist theory (the UberMensh bulls***etc...). The result was that the 109 was harder to perform than the Spit or the Hurri....

As a side note lets say that it is sad that the elliptical wing was made as a brand mark for vick-Sup. IMHO it leads to the rapid demise of the Supermarine design bureau as soon as the war ended (mid 50's).

It is also funny to see how history can repeat itself nowadays in Eu;-)

But this is way out of topic

~S!

[Sternjaeger II]

Viper, you know that I respect you because of your factual approach, and yes, there are a lot of misconceptions about the Spit wing design, but according to a gentleman in the UK who owns and regularly flies his Spit MkIX, his Hurri IIb and P-51D, the maneuverability of the Spit is unparalleled, simply because its wing behaves and performs better, albeit being more prone to torque along its span and flex ("the whole plane feeling is of extreme agility and flimsiness, it was obviously an aeroplane that has been based on a sport design and not conceived for war").

As for wing sturdiness, I have walked to the wingtip of a Mustang without the plane making a single movement, but you wouldn't be able to do the same on a Spitfire. A cannon strike on the single spar Spit wing is more likely to do more damage and above all weaken the structure enough to cause a fracture than on a robust Mustang double spar.

Let's not forget that a Mustang is almost twice the weight of a Spitfire!

[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.

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....:-P

[lane]

Pierre Clostermann, Spitfire pilot.
"I tried to fire on a '109' that I spotted in the chaos. Not possible, I couldn't get the correct angle. My plane juddered on the edge of a stall. It was comforting that the Spitfire turned better than the '109'! Certainly at high speed - but not at low speed."

Is that quote a fabrication? I’ve seen it on various aviation boards over the years and never once was it ever accompanied with a legitimate citation. Clostermann’s narrative in The Big Show seems to contradict that quote. Firstly it must also be said that Clostermann didn’t fly operationally during the Battle of Britain nor fly Spitfire I's in combat, so hoax or not, it doesn’t apply to Spitfire I/Me 109 E. His first operational sortie was with 341 Squadron in April 1943 flying Spitfire IXs.

Clostermann describing a Spitfire IX versus Me 109 G combat from 26th September, 1943:

"He knew that my Spitfire turned better and climbed better…" (See attachment)

Clostermann describing a Tempest V, Me 109 combat during 1945.
"I kept on reminding my pilots to keep their speed above 300 m.p.h., for “109’s” could turn better than we could at low speed…" (See attachment)

Something fishy…

[bugmenot]

Pierre Clostermann, Spitfire pilot.
"I tried to fire on a '109' that I spotted in the chaos. Not possible, I couldn't get the correct angle. My plane juddered on the edge of a stall. It was comforting that the Spitfire turned better than the '109'! Certainly at high speed - but not at low speed."

Cited in the "Great Show 2000". ;)

I don't remember reading this in the original "Great show" published in the 1940's

~S!.

[ICDP]

The quote is from the "Complete and Unabridged" version of the Big Show, published in 2004. Clostermann had many notes and diary entries that were not used in the original version.

See page 42, "My first big show over France". Clostermann was flying a Spitfire Mk IX against most likely 109Gs

[Kurfurst]

the Spitfire had the highest tactical Mach number of any WWII fighter, and could not be out-dived by any aircraft under control until the advent of the XP-86 in 1947.

'Fighter' seems to make the sentence untrue, given that the supposed .89 Mach figure was measured on an unarmed photo recce aircraft (ie. aerodynamic windshield, no cannons stubs, no MG ports ruining the flow over the wing); besides the fact that the said report of the PR XI dive measured does not mention a thing about control behaviour.. ;)

I have a report of a proper Mark IX (ie. Fighter) dive trial, and it shows exactly the same symptoms of loosing control as any other fighter above 0.80 Mach. Add to that the instruments were also inaccurate at these speeds, and you have a myth liked by fans, but with very little root in reality.

[justme262]

For what it's worth... here is an interview with a Battle of Britain Ju87 pilot in which he says a Hurricane could hang on the tail of a Stuka in a sustained turn but a Spitfire was too fast.


http://www.youtube.com/watch?v=McloM9Es3oM

[Sternjaeger II]

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 :grin:

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

[Viper2000]

'Fighter' seems to make the sentence untrue, given that the supposed .89 Mach figure was measured on an unarmed photo recce aircraft (ie. aerodynamic windshield, no cannons stubs, no MG ports ruining the flow over the wing); besides the fact that the said report of the PR XI dive measured does not mention a thing about control behaviour.. ;)

I have a report of a proper Mark IX (ie. Fighter) dive trial, and it shows exactly the same symptoms of loosing control as any other fighter above 0.80 Mach. Add to that the instruments were also inaccurate at these speeds, and you have a myth liked by fans, but with very little root in reality.

I didn't claim that a Spitfire fighter was capable of Mach 0.89 in a controlled dive. You seem to have set the PR.XI Mach number up as a straw-man.

The Spitfire Pilots Notes put the dive limit at 450 mph IAS (after position error; so really it's more like CAS but without the modern compressibility correction) or what was effectively Mach 0.85, the limit being defined by a lookup table due to the absence of a Mach meter.

I would suggest that Eric Brown is probably the best reference for relative performance of fighter aeroplanes because he flew so many types.

It's fine to argue instrument error when you're talking about squadron pilots diving in the heat of battle and seeing fantastic numbers on their ASI. Indeed, I'm more than happy to offer up the alleged Mach 0.92 dive by a Griffon Spitfire in the vicinity of Hong Kong post war as likely erroneous.

However, RAE were a competent flight test organisation, and they were perfectly capable of correcting for compressibility. The same goes for NACA, though it is notable that the USAAF went to RAE for an assessment of the high speed handling characteristics of their fighter aeroplanes (See Wings on my Sleeve).

Compressibility correction for a pitot tube really isn't that hard, especially subsonic when you can just say that gamma = 1.4.

Therefore I have considerable confidence in the Spitfire PR.XI dive data showing Mach 0.89; if you look at Morgan & Shacklady you'll see that the aeroplane was rather impressively instrumented for these high speed dives. I also note that this tended to break engines due to overspeeding, resulting in several serious accidents, despite the fact that the propeller was modified to feather in an attempt to contain rpm.

So I wouldn't claim that a Spitfire fighter could be safely operated by a squadron pilot at such a high Mach number.

But I have no reason to believe that it was unsafe to operate the aeroplane within its published envelope (i.e. the lower of 450 mph after position error correction, or Mach 0.85), not least because pilots tend to get quite vocal if aeroplanes scare them within the published envelope, and I also have no reason to disbelieve the tactical Mach numbers quoted by Eric Brown in his various books.

IIRC there may be some dive test data from a Spitfire IX showing a tactical limit of about Mach 0.83 out there somewhere. This would be fairly reasonable.

AFAIK the tactical limit for the Mustang is about 0.80, Thunderbolt about 0.72, Bf-109 and Fw-190A 0.75, whilst the P-38 was only ok to about 0.68. However, my books are at home; the numbers can be cross-checked in Wings on my Sleeve, Wings of the Luftwaffe, and Wings of the Weird & Wonderful.

[Sternjaeger II]

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

LOL I love you man :mrgreen:


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 :grin:


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).

[Sternjaeger II]

I would suggest that Eric Brown is probably the best reference for relative performance of fighter aeroplanes because he flew so many types.


Brown's accounts are a good read but hardly of any serious value man.. I think this is the biggest mistake: always looking for a source of comparison, but looking only into English literature on the subject.

The Germans had a lot of planes to play with, and I believe they might have produced an extensive literature on the subject, it would be interesting to hear from our German speaking friends on the matter.

[Viper2000]

Brown was at the RAE high speed flight; decision makers acted upon his views at the time. I don't think that you'll find a substantially better source.

The Germans didn't have the opportunity to test war trophies after VE day, so their literature is unlikely to be anything like as broad as that produced by the Allies, especially at the RAE; don't forget that the RAE were the world-leaders in high speed flight until the idiotic cancellation of the Miles M.52...

[Sternjaeger II]

Brown was at the RAE high speed flight; decision makers acted upon his views at the time. I don't think that you'll find a substantially better source.

questionable.. he wasn't the only pilot, only the one that bothered writing a somehow interesting (albeit incomplete and biased) text on his experience. RAE had to make a lot of compromises in their testings, so if you're looking for an accurate testing, look somewhere else.


The Germans didn't have the opportunity to test war trophies after VE day, so their literature is unlikely to be anything like as broad as that produced by the Allies, especially at the RAE; don't forget that the RAE were the world-leaders in high speed flight until the idiotic cancellation of the Miles M.52...

Brown's tests of our interest were mainly made during war years, the postwar years were more devoted to jet planes (he's claimed as the only Allied pilot who flew a Komet, but in fact he only glided in it).

The Luftwaffe had an extensive testing of captured planes (they even bothered to install a DB601 on a Spitfire to check its performance!).

I found some literature of interest:

"Luftwaffe Test Pilot, Flying captured Allied Aircraft of World War 2" Published in German in 1977 and English in 1980. Author: Hans-Werner
Lerche.

1. Strangers in a Strange Land Vol. 1 (Squadron Signal pub) by Hans Heiri Stapfer. Usually available on the web for
$ 10 - $ 15 used condition. A number of photos and color drawings are included as well as interesting discussions on specific aircraft that were captured.

2. Fremde Vogel unterm Balkenkreuz I have scanned photos from this book, but haven't been able to find a copy for sale.....it contains a number of photos of captured
aircraft in Luftwaffe service organized by country of origin. This book was published in the early 1980s I think.

3. Il Ricco Bottino (The Rich Booty) by Hans Werner Neulen. Excellent book on captured Italian aircraft in Luftwaffe service. around $ 18.

4. The Luftwaffe from Training School to the Front (Chapter 10) by Meyer and Stipdonk. Chapter 10 provides a number of photos of captured aircraft.

5. Foto Archiv Band 8. Although several Band in this excellent publication include at least one or two photos of captured aircraft..Band 8 includes by far the most with
several types I not seen elsewhere. You can order this one online at the following site:
www.stormbirds.com/flugzeug/ (http://www.stormbirds.com/flugzeug/)

Flugzeug magazine and Jet & Prop magazine, also available at this web address, have published excellent articles on this subject. Included are: Fiat G-12; Bloch SO 161;
Hopfner Ha 11/33; Brequet Br 521 Bizerte (2 parts); SM-75/SM 82; Rechlin September 1943 display; SE 200 etc.

6. Luftwaffe Fledglings 1935 - 1945. by Ketley and Rolfe. Although not exclusively about captured aircraft, this book nevertheless contains quite a bit of interesting
information, photos and drawings concerning captured aircraft used as trainers.

7. Modell Fan magazine ran a series of articles in the late 1970s and early 1980s entitled 'Sie Flogen mit dem Balkenkreuz' there were at least 13 or 14 articles in this
series, maybe more.

8. The Czech magazine REVI has published comprehensive articles by Igor Mrkvanek on captured Czech aircraft in Luftwaffe service. Very informative.

9. Flypast has published at least two very interesting articles on captured British aircraft in Luftwaffe Service.

10. Luftwaffe Codes, Markings and Units (Barry Rosch) contains quite a bit of information on captured aircraft organized by Luftwaffe unit. Some photos and drawings of
captured aircraft are included throughout the book.

11. The Luftwaffe Verband Journal has published several articles on aircraft evaluated at Rechlin or operated by Versuchsverband.

[Sternjaeger II]

uh and "KG 200 - The True Story" by Peter Stahl

[Viper2000]

questionable.. he wasn't the only pilot, only the one that bothered writing a somehow interesting (albeit incomplete and biased) text on his experience. RAE had to make a lot of compromises in their testings, so if you're looking for an accurate testing, look somewhere else. Having met the man a few years ago I must say that I found him convincing, and most impressive.

The biggest problem with his books is the fact that the typist doesn't understand engine power settings and therefore incorrectly converts between psi boost and ata throughout the text, littering it with parenthetical errors which were obviously absent from the original manuscript.

Brown's tests of our interest were mainly made during war years, the postwar years were more devoted to jet planes (he's claimed as the only Allied pilot who flew a Komet, but in fact he only glided in it). Actually he illicitly flew it under power in 1945; see the latest edition of Wings on my Sleeve. He also tested a number of piston engined types post war, most notably the Ta-152 (albeit with neither MW50 nor GM1) and Do-335.

The Luftwaffe had an extensive testing of captured planes (they even bothered to install a DB601 on a Spitfire to check its performance!). I suspect that they did this after an engine failure in order to make the best possible use of a rare captured airframe; there might also have been some political purpose (both internal, so that DB could demonstrate their good works to their masters) or external (IIRC they were quick to suggest that the DB engine was an improvement).

I found some literature of interest:

"Luftwaffe Test Pilot, Flying captured Allied Aircraft of World War 2" Published in German in 1977 and English in 1980. Author: Hans-Werner
Lerche. Got it somewhere. It's interesting, though rather less technical than Brown's books. I seem to recall that quite a lot of emphasis was placed upon taking captured aeroplanes to German fighter squadrons so that they could see them up close. His observation that the B-17 was only fast due to its turbochargers is obviously correct, but of course all's fair in love and war!

I don't recall as much interest in tactical Mach numbers as was displayed by the Allies, because in the late war period the Germans often found themselves climbing into battle, whilst the Allied escort fighters were diving from on-high.

1. Strangers in a Strange Land Vol. 1 (Squadron Signal pub) by Hans Heiri Stapfer. Usually available on the web for
$ 10 - $ 15 used condition. A number of photos and color drawings are included as well as interesting discussions on specific aircraft that were captured.

2. Fremde Vogel unterm Balkenkreuz I have scanned photos from this book, but haven't been able to find a copy for sale.....it contains a number of photos of captured
aircraft in Luftwaffe service organized by country of origin. This book was published in the early 1980s I think.

3. Il Ricco Bottino (The Rich Booty) by Hans Werner Neulen. Excellent book on captured Italian aircraft in Luftwaffe service. around $ 18.

4. The Luftwaffe from Training School to the Front (Chapter 10) by Meyer and Stipdonk. Chapter 10 provides a number of photos of captured aircraft.

5. Foto Archiv Band 8. Although several Band in this excellent publication include at least one or two photos of captured aircraft..Band 8 includes by far the most with
several types I not seen elsewhere. You can order this one online at the following site:
www.stormbirds.com/flugzeug/ (http://www.stormbirds.com/flugzeug/)

Flugzeug magazine and Jet & Prop magazine, also available at this web address, have published excellent articles on this subject. Included are: Fiat G-12; Bloch SO 161;
Hopfner Ha 11/33; Brequet Br 521 Bizerte (2 parts); SM-75/SM 82; Rechlin September 1943 display; SE 200 etc.

6. Luftwaffe Fledglings 1935 - 1945. by Ketley and Rolfe. Although not exclusively about captured aircraft, this book nevertheless contains quite a bit of interesting
information, photos and drawings concerning captured aircraft used as trainers.

7. Modell Fan magazine ran a series of articles in the late 1970s and early 1980s entitled 'Sie Flogen mit dem Balkenkreuz' there were at least 13 or 14 articles in this
series, maybe more.

8. The Czech magazine REVI has published comprehensive articles by Igor Mrkvanek on captured Czech aircraft in Luftwaffe service. Very informative.

9. Flypast has published at least two very interesting articles on captured British aircraft in Luftwaffe Service.

10. Luftwaffe Codes, Markings and Units (Barry Rosch) contains quite a bit of information on captured aircraft organized by Luftwaffe unit. Some photos and drawings of
captured aircraft are included throughout the book.

11. The Luftwaffe Verband Journal has published several articles on aircraft evaluated at Rechlin or operated by Versuchsverband.

[Sternjaeger II]

Having met the man a few years ago I must say that I found him convincing, and most impressive.

don't get me wrong, the man is a LEGEND! I met him last year or two years ago at Duxford and I was honoured to shake hands with him! but as you pointed below..


The biggest problem with his books is the fact that the typist doesn't understand engine power settings and therefore incorrectly converts between psi boost and ata throughout the text, littering it with parenthetical errors which were obviously absent from the original manuscript.

de facto making it an interesting read, but not quite the reliable reference that we need :(


Actually he illicitly flew it under power in 1945; see the latest edition of Wings on my Sleeve. He also tested a number of piston engined types post war, most notably the Ta-152 (albeit with neither MW50 nor GM1) and Do-335.
now that's interesting! I have the older version, bugger!
The thing that you point about the Ta-152 happened with other planes as well: the incorrect use (or lack) of fuels meant that they were more general handling tests instead of performance ones.


I suspect that they did this after an engine failure in order to make the best possible use of a rare captured airframe; there might also have been some political purpose (both internal, so that DB could demonstrate their good works to their masters) or external (IIRC they were quick to suggest that the DB engine was an improvement).

apparently it was just a genuine performance test to see whether they could improve the handling of their 109s, have a look at this interesting article
http://www.unrealaircraft.com/hybrid/spitfire.php


Got it somewhere. It's interesting, though rather less technical than Brown's books. I seem to recall that quite a lot of emphasis was placed upon taking captured aeroplanes to German fighter squadrons so that they could see them up close. His observation that the B-17 was only fast due to its turbochargers is obviously correct, but of course all's fair in love and war!

I don't recall as much interest in tactical Mach numbers as was displayed by the Allies, because in the late war period the Germans often found themselves climbing into battle, whilst the Allied escort fighters were diving from on-high.

this proves though that surely there are other tests that have been made and data has been collected, sourcing it is another story though..

[Viper2000]

de facto making it an interesting read, but not quite the reliable reference that we need :(
It's pretty easy to untangle the typographical errors because the conversions are in parentheses, obviously added by the typist after the fact. You can just ignore them and then it's all good. In any case, the conversion errors tend to be glaring - provided that you know roughly what the correct answer should be, it's pretty easy to weed them out.

The main advantage of Brown's test results is that they are internally consistent; it's the same guy flying all the aeroplanes, so you get a real comparison between aeroplanes rather than a comparison between pilots.

This is especially important when you come to consider handling, since it was strength limited in large parts of the envelope, particularly at high speed.

His tests of German aeroplanes are especially good because of course his German was good enough that he understood the captions in the cockpit, could interrogate pilots & ground crew, read manuals if available etc.. This means that there's considerably less risk of under-performance due to poor technique than might otherwise be the case.

now that's interesting! I have the older version, bugger! I think that he decided that the statute of limitations had expired for the latest edition... AFAIK he just flew the thing for the heck of it, on the basis that the fuel was going to be disposed of and the aircraft scrapped, so why not? (Other than the obvious health & safety issues of course).

The thing that you point about the Ta-152 happened with other planes as well: the incorrect use (or lack) of fuels meant that they were more general handling tests instead of performance ones. This sort of thing applies to all captured aeroplanes; you have to read the small print very carefully so that you know what you're actually comparing.

The lack of MW50 & GM1 doesn't necessarily fatally compromise the Ta-152 tests, since you can calculate the additional power which they would have provided and hence deduce what the maximum performance would have been. Of course, to do this properly you need to have enough other test data to infer the shape of the drag polar, but you only really need this information for a relatively narrow range of CL. It's really amazing how much you can deduce about aircraft performance from quite limited data. In fact, some people make careers of it.

For example, one of the main reasons for scrupulously fitting exhaust nozzle blanks to shiny new fighter jets when they're in the static park at an airshow is that if I know the nozzle throat area then an experienced observer estimate the engine thrust with rather better accuracy than the layman might expect.

In any case, the handling is generally more interesting than the kinematic performance, since it's far easier to calculate kinematic performance than it is to calculate handling characteristics, especially at transonic speeds.

apparently it was just a genuine performance test to see whether they could improve the handling of their 109s, have a look at this interesting article
http://www.unrealaircraft.com/hybrid/spitfire.php

I think I might have come across this before at some point. The comparison argument is a strange one, because firstly it's irrelevant to combat, and secondly no two installations are alike in any case.

Since the Germans weren't stupid, my best guess is that:


They expected engine failure, and therefore opted to premptively replace the engine.
They realised that the Spitfire V was obsolete, but since they didn't have high performance fuel they couldn't investigate its development potential by over-boosting the engine; therefore the only way to investigate the aircraft's ability to handle extra power was to add the next generation of DB engine instead.


In the latter instance, this would imply that they were yet to capture a flyable Mark IX or XII.

It's worth noting that the RAE, with access to high grade fuels, took the former route with their early captured Fw190s, handily exceeding rated boost (and possibly rpm, though I'd have to check my copy of Wings of the Luftwaffe). I suppose this might technically be called the fly it like you stole it approach...

[QUOTE=Sternjaeger II;281235]this proves though that surely there are other tests that have been made and data has been collected, sourcing it is another story though..

I have no doubt that the Germans collected vast amounts of data on a myriad of subjects, since that is their nature, but I suspect that a lot of it either went up in smoke some time in 1945 or else was carted off by one or other of the victorious Allies (most likely the USSR or the USA; the British mission essentially consisted of whatever Sir Roy Feddon could beg or borrow, and much of what he obtained was instantly stolen at gunpoint by the yanks...).

However, it's important to remember that the Germans were under no obligation to (for example) use the same standard atmosphere assumptions as us, or to test their aeroplanes according to the same methodology. So if you want to make a really satisfactory comparison it's not sufficient to just perform a unit conversion and overlay the data; you've got to actually drill down to find out what the assumptions underlying the test results were, and then correct everything to a common standard.

Otherwise it's apples vs oranges.

I think I went into this in my flight testing thread.

Hopefully in a few patches time, when things are sufficiently stable for serious testing, we will have amassed enough of this underlying information on assumptions to allow everything to be converted to modern ISO standard conditions so that fair comparisons can be made.

However, since I don't have a great deal of German data on test methodologies, German standard atmospheres and so on, I'm very much reliant upon the wider community to fill in the gaps.

[TomcatViP]

Ta 152, Spit Pr XII, Komet ... Where are our sturdy early war planes Hurri and Spit I ???

[TomcatViP]

LOL I love you man :mrgreen:



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.

[Kurfurst]

I didn't claim that a Spitfire fighter was capable of Mach 0.89 in a controlled dive. You seem to have set the PR.XI Mach number up as a straw-man.

No straw man here, the PR.XI PR Mach number is just happens to be the most commonly referenced. ;)


But I have no reason to believe that it was unsafe to operate the aeroplane within its published envelope (i.e. the lower of 450 mph after position error correction, or Mach 0.85), not least because pilots tend to get quite vocal if aeroplanes scare them within the published envelope, and I also have no reason to disbelieve the tactical Mach numbers quoted by Eric Brown in his various books.

IIRC there may be some dive test data from a Spitfire IX showing a tactical limit of about Mach 0.83 out there somewhere. This would be fairly reasonable.

AFAIK the tactical limit for the Mustang is about 0.80, Thunderbolt about 0.72, Bf-109 and Fw-190A 0.75, whilst the P-38 was only ok to about 0.68. However, my books are at home; the numbers can be cross-checked in Wings on my Sleeve, Wings of the Luftwaffe, and Wings of the Weird & Wonderful.

What is a 'tactical limit'? :confused:

Basically I think the Mach 0.85 dive limit is arbitrary, ad hoc, ex stomach etc. - a bold guesswork that was set well before they would test the actual capability, just like many of the era's limits, though a bit bolder..

But, personally I believe the behaviour shown by fighter Mark IX BS 310 was certainly no greatly different - better or worse - than just about any WW2 fighter: controls functioned normally up to about .70 Mach, then all sorts of anomalies began to appear.. and at 0.815, there's already a longitudal pitching motion - and 0.85 is still rather far away..

http://i38.photobucket.com/albums/e133/Kurfurst/Spitfire/Spit_IX_divebehaviour.png

[41Sqn_Stormcrow]

Just to add affirmative information about what Viper said about the elliptical wing design of the Spit a little albeit interesting information on a footnote in aeronautical warfare history about a plane that didn't make it into mass production but would have produced a mess if it had been mass produced (you'll quickly will see why): the Heinkel He 112 that had been the most serious competitor against the Me109 during the evaluation trials in 1935 but which - as we know - was won by the 109.

http://en.wikipedia.org/wiki/He_112

http://www.aviastar.org/air/germany/he-112.php

Although the He 112 did have elliptical wings and wing-to-fuselage transition similar to the Spit its first prototypes had some problems with speed and the designers suspected some extra drag they didn't take into account during the initial design stages. They solved it in the course of pre series development but the contract has already gone to Messerschmitt. So obviously elliptical wings aren't the miracle some come to think.

Some nice pics and a short video clip on the 112 used as a testped:
http://www.cockpitinstrumente.de/Flugzeuge/Transporter/He%20112/Heinkel%20He%20112%20%20Profil.html

[Viper2000]

No straw man here, the PR.XI PR Mach number is just happens to be the most commonly referenced. ;)



What is a 'tactical limit'? :confused: I'm using the nomenclature adopted by Eric Brown, which is that the tactical Mach number is the maximum Mach number at which the aeroplane may be used tactically, whilst the Critical Mach number is the maximum Mach number at which the aeroplane may be controlled. I am personally of the view that tactically in this context probably means offensively, because you can obviously frustrate an enemy's gun solution after having departed from controlled flight...

Obviously, with manual controls, both of these Mach numbers depend upon pilot strength.

Limits in the Pilot's Notes are there to protect the airframe and engine from harm, so they will tend to correlate more closely with what Brown would call the critical Mach number than with what he would call the tactical Mach number.

N.B. - This nomenclature is inherently confusing the aerodynamicists, who would tend to think of the critical Mach number as the lowest freestream Mach number at which sonic flow is seen around whatever shape they're examining. Therefore, for example, you can't look up aerofoil critical Mach numbers in Abbot & Doenhoff and compare them with flight test reports.

Basically I think the Mach 0.85 dive limit is arbitrary, ad hoc, ex stomach etc. - a bold guesswork that was set well before they would test the actual capability, just like many of the era's limits, though a bit bolder.. I am inclined to disagree, because Henshaw et al routinely conducted dive tests to the limiting CAS as part of their production testing at Castle Bromwich. This actually involved diving to 470 mph IAS because the instrument error was assumed to be 20 mph IAS. So there was no great shortage of knowledge as to the behaviour of the aeroplane at the placarded limits of its envelope.

But, personally I believe the behaviour shown by fighter Mark IX BS 310 was certainly no greatly different - better or worse - than just about any WW2 fighter: controls functioned normally up to about .70 Mach, then all sorts of anomalies began to appear.. and at 0.815, there's already a longitudal pitching motion - and 0.85 is still rather far away.. By Mach 0.70 a P-38 would already have departed from controlled flight...

I'd say that it's probably reasonably safe to place the tactical Mach number of the Spitfire at approximately 0.80, perhaps higher for the Griffon Spitfire due to its longer nose and correspondingly higher fineness ratio.

Additionally, comparison with the P-51D is interesting:

http://www.wwiiaircraftperformance.org/mustang/mustangIV-divetest.html

http://www.wwiiaircraftperformance.org/mustang/p-51d-dive-27-feb-45.pdf

IMO the Spitfire comes out of this comparison looking pretty good.

http://i38.photobucket.com/albums/e133/Kurfurst/Spitfire/Spit_IX_divebehaviour.png

Do you have the rest of this report? It's interesting stuff.

Note, however, that it's a somewhat different animal from the PR.XI tests. The PR.XI tests were aimed at getting the highest possible Mach number on the clock. They therefore involved dives from about 40000', the maximum Mach number being reached at about 29000' with the aeroplane unloaded; recoveries were pretty gentle at about 2 g.

Meanwhile, your report appears to be an attempt to investigate the effect of Mach number upon CLmax; it talks about 5 g recoveries, which is pretty brave out at the edge of the envelope; the Mustang dive tests emphasise the risk of structural failure unless extremely gentle recoveries are made from high Mach number dives.

It's hardly surprising that the maximum Mach number at which you can really throw the aeroplane around would be lower than that which can be reached if gentle flying. I'm actually quite surprised that the Spitfire would tolerate this sort of handling at such high Mach numbers; there's no mention of rivets popping, things bending, breaking or falling off etc. I can't think of any other WWII fighter that would repeatedly tolerate >5 g at M>0.80 without complaint.

So I suppose that a lot of this stuff is in the eye of the beholder, but if I had to spend my time at the top right hand corner of the envelope for real in a WWII fighter then I'd pick a Spitfire to do it in.

The caveats regarding date collection in the report are important; it's quite hard to work out exactly what the uncertainties are with this sort of test. They might easily be as high as +/- 0.03 M.

In this respect the PR.XI data is better because an auto observer was used AFAIK, and of course the aeroplane was quite heavily instrumented and modified in other respects as well. So I'm quite confident that their quoted Mach 0.89 is +- a rather small error (though I don't make any particular claim as to the applicability of this figure to an operational aeroplane on a squadron, beyond the qualitative implication that the basic airframe was selected for dive tests by the high speed flight because it had the best high Mach number characteristics available off the shelf).

However, it's important to make the distinction between the uncertainty due to observational difficulties, those due to lack of instrumentation, and those due to instrument errors.

For example, if the ambient conditions (especially static temperature) aren't recorded, there might be a considerable error in Mach number due to differences between the test day and standard atmosphere conditions. Not much can be done about this, because even a couple of hours later the weather can and probably will have changed.

OTOH, it's much easier to go back a few weeks later and correct for instrument error by careful calibration of the instruments used during the test, and measurement uncertainly can be reduced by repeating the tests and applying statistics.

I point this out because there is a tendency for certain sections of the community to suggest that just because some reported dive is considered bogus (usually a combat report for their favourite aeroplane citing 600 mph IAS or something) that all dive testing is bogus. The reality was of course that it was merely difficult to get good data in the 1940s; serious flight test organisations could do it, whereas the average fighter pilot could not, because nobody had seen fit to give him the necessary tools to do so.

///

Tomcat et al, conventional elevators work by modifying the camber of the tail section.

Moving the relatively small control surface therefore affects the CL of the entire tail.

The force required to do this is set by the hinge moment.

At high freestream Mach number you get sonic flow over the tail. The control surface cannot affect the pressure distribution over the tail surface upstream of the sonic line. So the control effectiveness suddenly dramatically declines.

Since the control deflection was limited by pilot strength, the effect that the pilot perceives is a nose down pitching moment, because he's pulling as hard as he can, and the stick stays in the same place. But what's really happened is that the elevator effectiveness has declined, which is equivalent to reducing the absolute camber of the tail.

This means that high Mach number departure was often a 2 stage phenomenon. First the aeroplane starts wanting to pitch down due to shock formation on the wing changing the downwash angle over the tail. Then at some higher Mach number the effectiveness of the elevator fades away and the nose down pitching tendency gets worse. A lot of aeroplanes wouldn't really get into this second regime because they'd either break or start slowing down and getting into warmer air first.

Obviously, an all moving tail doesn't have this elevator problem because it just changes alpha rather than translating its lift curve slope with camber changes.

It has other problems due to the force required to actuate it, possible overbalance etc. But you can fix most of them by just throwing massive irreversible screwjacks at it, although it is advisable to combine this with Q feel so that the pilot doesn't inadvertently break the aeroplane when flying fast...

Yeager suggests that keeping the flying tail secret allowed the F-86 to have a technological lead over British and Russian aeroplanes of the period, but really this is an oversimplification because the idea of the all moving tail was not new. The rather more mundane reality is that getting the enabling technologies in the rest of the control system to work wasn't a trivial problem in the 1940s, and in Britain almost all of the funding for such work evaporated in 1945, whereas in America it kept on flowing. Meanwhile the Russians had slightly different priorities, but it's probably fair to say that the kill ratio achieved by the UN in the Korean war was probably more a function of pilot skill than aircraft performance differences (though the F-86 was superior at high Mach number, it was certainly far from perfect).

BTW, the first generation X-1 wasn't as clever as the M.52.

AFAIK the M.52 had no elevators and just moved its entire horizontal tail for pitch control "out of the box".

The X-1 had elevators for pitch and an all moving tail for trim (rather like a Bf-109, except that the X-1 moved the tail electrically, and the control was a coolie hat on top of the stick).

The elevators became ineffective somewhere in the transonic regime (0.9ish) and the workaround was to hold the stick still and control pitch with the trimmer.

I assume that the 2nd generation aeroplanes ditched the elevator...

Of course, despite its aerodynamic sophistication, it's not entirely certain that the M.52 would actually have been supersonic in level flight as drawn because this would have been asking an awful lot of its engine.

But now we're waaaaay OT.

[Sternjaeger II]

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....:rolleyes:

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]

The Hurricane's higher wing aspect ratio helped turn rates at higher speeds due to the increased lift created.


Yup... But don't forget to add the effect of thicker of the airfoil that generate more lift at lower speed (less AoA) -> smaller turn radius

Good post by the way - Thx :-)

[41Sqn_Stormcrow]

As (I think) Viper had said previously the pilot's account have to be taken with a tiny bit of grain of salt.

The thick winks of the Hurry in itself may have produced more lift but also more drag. In fact what is interesting to know for turn rates is the angle of attack needed for the turn rate and the drag it produces and finally the engine power and weight.

The engine power vs drag will overall determine the speed at which the ac will travel through air.

The lift generated vs. current airspeed and weight will determine the ability to change direction = turn rate.

The more engine power I have I may pull more angle of attack without loss of speed and the higher the lift will be. It is the lift that will cause my ac to turn. At the same time for same engine the less drag angle of attack produces the better I turn.

[TomcatViP]

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 :rolleyes:)

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 ! :-P

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

~S!

[41Sqn_Stormcrow]

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 ... :)

[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.

[TomcatViP]

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.

[41Sqn_Stormcrow]

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.

[41Sqn_Stormcrow]

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.

[Sternjaeger II]

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

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 ! :-P

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

~S!

uhmmm it's still a matter of proportions, especially when getting to supersonic speeds.

When doing wind tunnel studies, the transonic/supersonic experiments need to be made on a life size model to make an accurate observation of the shock phenomena, which behave and change dramatically according to the size of models.

I would like to hear Viper's opinion on the matter, do you reckon tail surfaces would hit compressibility before wings or viceversa?

[Viper2000]

I would like to hear Viper's opinion on the matter, do you reckon tail surfaces would hit compressibility before wings or viceversa?

I think the only reasonable answer to a question like that is "It depends...".

Really this "hit compressibility" concept is horrid. Air is compressible all the time. If you go fast then compressibility becomes more important. But I'd generally be inclined to consider compressibility in calculations for M>0.2 if I wanted accurate answers. Really the Mach number at which you elect to consider compressibility is a bit like the temperature at which you decide to account for variation in the Cp of dry air - it's arbitrary, and depends upon the computational resources available and the effort you're prepared to put in.

I'd generally expect the tail to be lower aspect ratio than the wing. Therefore it can be thinner. I'd also expect it to be at lower absolute CL than the wing. So, if we assume the same amount of sweep for wing and tail, I'd expect the tail to remain subsonic to a higher freestream Mach number than the wing.

But the generalisations associated with the above are dramatic. Control deflection, variations in wing downwash angle and so on could easily make quite a big difference.

In the WWII context, with manual controls you're likely to find that the pilot runs out of bicep before shockwave development over the tail starts to bite.

Here's a quick list of the factors causing "Mach tuck":

Migration of the wing's centre of pressure
Changing wing downwash angle
Rapidly increasing stick force for constant elevator deflection
Reduced elevator effectiveness due to shock developement over the tail


You can see that 3 out of the 4 don't require shock development over the tail.

OTOH, the underlying problem is the tail; because that's where the control surfaces are, and the problem is a control problem.

So the brute-force approach towards the end of WWII and immediately thereafter was to hydraulically boost everything. Once you do that then the new problems are dealing with the failure modes and providing Q feel so that the pilot doesn't break the aeroplane.

Then you might get into trouble with lack of elevator effectiveness, because the elevator can't affect the pressure distribution upstream of any shock which may have formed over the tail. But really it's unreasonable to think of the flying tail as a "solution" to this problem, because going to a flying tail in 1940 wouldn't have solved fighter stability & control problems. Without irreversible screwjacks to drive the thing, you'd find that either it fluttered off or else the control forces were impossibly high.

Really the concept of the "flying tail" is a sort of marketing thing rather than reality. There's nothing magic about it. The simple reality is that if you're supersonic the you need the movable bit of your control surface to do all the work by itself, and you therefore have to size it appropriately. Note that delta winged fighters do just fine with elevons - no need for the surface to have its own private leading edge to work - it just needs to be big enough and to be driven by a sufficiently strong set of jacks.

In subsonic flight the elevator can be quite a lot smaller because it affects the lift curve slope of the whole surface it's attached to, which is great if you've only got a relatively limited actuating force available. Hence the rapid ubiquitous adoption of the elevator in subsonic aeroplanes quite early in the evolution of the aeroplane.

The other thing which people got used to is the idea that in general a nice set of aerodynamic controls will give you stick free stability which may well mask any nasty stick-fixed behaviour your design may exhibit. During WWII the added friction associated with pressurised cockpits started to show up some of the stick fixed problems that had been lurking under the rug for decades, and this caused people to start working on tweaking the control system itself via bob-weights etc to affect the subjective handling characteristics of the aeroplane, rather than just expecting the pilot to tolerate what he was given.

This gradually took us towards full FBW/manoeuvre demand systems, which allow you to design the apparent handling of aeroplanes to be almost independent of their aerodynamics. Which is great, though it does open all sorts of philosophical cans of worms since you now have to think about what the ideal set of control laws would be, rather than just asking the test pilot whether he can fly the thing or not...

The loss of stick free stability also rather reduced the importance of the fixed portion of the tail from a handling perspective, and since the elevator had to be big enough for the supersonic control task, it was almost always going to end up big enough for the subsonic case and therefore why not just bin the fixed tail?

Actually there are several reasons, especially for larger aeroplanes; essentially a fixed tail with an elevator is likely to be lighter, though you may have to also vary its incidence for trim, which takes some of the advantage away (though the trim change can be an order of magnitude slower than the control trim, since effectively the trim change has to damp the phugoid whilst the control change has to damp the short period oscillation, and therefore the trim actuators can be smaller).

But I digress; time to get a cup of tea & get back to my thesis...

[Viper2000]

For me these are quite futile.

I wouldn't go quite that far, but certainly I'd be much more interested in turn rate than turn radius if I flew fighter aeroplanes for a living.

[Sternjaeger II]

sorry man, that's pilot jargon, the correct question would be "do you reckon that the effects of air compressibility would affect first the control surfaces or the wing?".

Thinking about the effects of compressibility puts the whole research and introduction of delta wings and canard wings into a very interesting perspective :)

[Viper2000]

sorry man, that's pilot jargon

No no no! Please watch the following training videos immediately.

Pilots use banter.
http://www.youtube.com/watch?v=5rKYL0tW-Ek

Only engineers are allowed to use jargon.
http://www.youtube.com/watch?v=bOV0v1Uq5CY

[TomcatViP]

I think the only reasonable answer to a question like that is "It depends...".

Really this "hit compressibility" concept is horrid. Air is compressible all the time. If you go fast then compressibility becomes more important. But I'd generally be inclined to consider compressibility in calculations for M>0.2 if I wanted accurate answers. Really the Mach number at which you elect to consider compressibility is a bit like the temperature at which you decide to account for variation in the Cp of dry air - it's arbitrary, and depends upon the computational resources available and the effort you're prepared to put in.

I'd generally expect the tail to be lower aspect ratio than the wing. Therefore it can be thinner. I'd also expect it to be at lower absolute CL than the wing. So, if we assume the same amount of sweep for wing and tail, I'd expect the tail to remain subsonic to a higher freestream Mach number than the wing.

But the generalisations associated with the above are dramatic. Control deflection, variations in wing downwash angle and so on could easily make quite a big difference.

In the WWII context, with manual controls you're likely to find that the pilot runs out of bicep before shockwave development over the tail starts to bite.

Here's a quick list of the factors causing "Mach tuck":

Migration of the wing's centre of pressure
Changing wing downwash angle
Rapidly increasing stick force for constant elevator deflection
Reduced elevator effectiveness due to shock developement over the tail


You can see that 3 out of the 4 don't require shock development over the tail.

OTOH, the underlying problem is the tail; because that's where the control surfaces are, and the problem is a control problem.

So the brute-force approach towards the end of WWII and immediately thereafter was to hydraulically boost everything. Once you do that then the new problems are dealing with the failure modes and providing Q feel so that the pilot doesn't break the aeroplane.

Then you might get into trouble with lack of elevator effectiveness, because the elevator can't affect the pressure distribution upstream of any shock which may have formed over the tail. But really it's unreasonable to think of the flying tail as a "solution" to this problem, because going to a flying tail in 1940 wouldn't have solved fighter stability & control problems. Without irreversible screwjacks to drive the thing, you'd find that either it fluttered off or else the control forces were impossibly high.

Really the concept of the "flying tail" is a sort of marketing thing rather than reality. There's nothing magic about it. The simple reality is that if you're supersonic the you need the movable bit of your control surface to do all the work by itself, and you therefore have to size it appropriately. Note that delta winged fighters do just fine with elevons - no need for the surface to have its own private leading edge to work - it just needs to be big enough and to be driven by a sufficiently strong set of jacks.

In subsonic flight the elevator can be quite a lot smaller because it affects the lift curve slope of the whole surface it's attached to, which is great if you've only got a relatively limited actuating force available. Hence the rapid ubiquitous adoption of the elevator in subsonic aeroplanes quite early in the evolution of the aeroplane.

The other thing which people got used to is the idea that in general a nice set of aerodynamic controls will give you stick free stability which may well mask any nasty stick-fixed behaviour your design may exhibit. During WWII the added friction associated with pressurised cockpits started to show up some of the stick fixed problems that had been lurking under the rug for decades, and this caused people to start working on tweaking the control system itself via bob-weights etc to affect the subjective handling characteristics of the aeroplane, rather than just expecting the pilot to tolerate what he was given.

This gradually took us towards full FBW/manoeuvre demand systems, which allow you to design the apparent handling of aeroplanes to be almost independent of their aerodynamics. Which is great, though it does open all sorts of philosophical cans of worms since you now have to think about what the ideal set of control laws would be, rather than just asking the test pilot whether he can fly the thing or not...

The loss of stick free stability also rather reduced the importance of the fixed portion of the tail from a handling perspective, and since the elevator had to be big enough for the supersonic control task, it was almost always going to end up big enough for the subsonic case and therefore why not just bin the fixed tail?

Actually there are several reasons, especially for larger aeroplanes; essentially a fixed tail with an elevator is likely to be lighter, though you may have to also vary its incidence for trim, which takes some of the advantage away (though the trim change can be an order of magnitude slower than the control trim, since effectively the trim change has to damp the phugoid whilst the control change has to damp the short period oscillation, and therefore the trim actuators can be smaller).

But I digress; time to get a cup of tea & get back to my thesis...

Any how I managed to write it down it seems that the tail has to be looked with suspiciousness.

When it comes to fluid mechanics don't be obsessed by tail's story
:rolleyes:


Just to make thing more clear and easier : the path to supersonic speed at those time went troughs symmetrical airfoils then to the all flying tail (AFT) unit. I am not sure that a full array of Bell and NACA engineers would hve been fooled such a way to design the X1 with a conventional tail if it could hve not fly faster than Mach 0.66 (compressibility).

idem for the F86 with thckness ratio decrease then AFT

[Danelov]

Why do Spitfires turn better than Hurricanes?!

Easy, the magic wings of Mr Reginald Mitchell, that is all.

[Formula88]

A better question is why do Hurricanes out climb and are faster in level flight than 1a spits...

[609_Huetz]

C
S
P

;)

On a serious note, it's a pain in the a** to see a historical flaw like that ingame day after day.

[Sternjaeger II]

Any how I managed to write it down it seems that the tail has to be looked with suspiciousness.

When it comes to fluid mechanics don't be obsessed by tail's story
:rolleyes:


Just to make thing more clear and easier : the path to supersonic speed at those time went troughs symmetrical airfoils then to the all flying tail (AFT) unit. I am not sure that a full array of Bell and NACA engineers would hve been fooled such a way to design the X1 with a conventional tail if it could hve not fly faster than Mach 0.66 (compressibility).

idem for the F86 with thckness ratio decrease then AFT

I don't think you understand what I mean man, but I'm afraid I'll have to give up on this, since you don't really seem to read the answers, you just wait to reiterate your theories.. :(

[335th_GRAthos]

No no no! Please watch the following training videos immediately.

Only engineers are allowed to use jargon.
http://www.youtube.com/watch?v=bOV0v1Uq5CY



Ahahahahahahahaha!!!!!!!

E X C E L L E N T !!!!!

[bugmenot]

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.

[beepee]

Yes but is it a fact that their turn times were more than 6 seconds better? :)

This is the real problem.

And anyway could really the Spit outturn the 109 at stall speed? (slats)wing loading!!

[Crumpp]

wing loading!!

Slats = Higher CLmax!! :-P

[41Sqn_Stormcrow]

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.

[TomcatViP]

10% is a huge diff IMHO.

Wing loading does not makes all. Section profile plays it's part here : at same weight, the more lift at equal wing area, the less the turn radius will be.

If you like RoF and WWI planes, look at the wing profile of a Focker and compare it to an Se5 or a Camel : Both the latter had barn door for wings (flat profiles), when the Focker used a thicher and aero refined wing profile. That's where the Focker gets it's fame.

There is now a similarity with the case discussed here btw the Hurri and the Spit. Even if the Spit balanced designed (12% thickness ratio) was good enough to match closely the old and thicker airfoil (ClarckY 19% - clarckY design were "draggier" but easier to built thx to their flat underside ) it was still much thinner requiring a higher speed in the turn (to get a low drag configuration (AoA)) hence a greater turn radius.

That is simple and a well known fact since WWII and I hardly see why it has to be discussed so much.

The Spit was a great design for its time but it has not the upper hand in every corner of flight perf .... Well IMHO none had ;-)

[41Sqn_Stormcrow]

You misread me, Tom. In REAL life turning circle, 10% difference is a big difference, here on this point I agree with you. What I was talking about is the error induced by numbers resulting from thump rule calculations. The friend of Mr. Bungay made these thump rule calculations for the turning circle for the Spit, the Hurri and the 109. Now from my experience thum rule calculations contain errors that can be huge with respect to reality and beyond 10%. So if a thump rule says the turning circle of the Spit is 690 ft and we assume the error in this calclation is 10% then the real life turning circle would be expected in between 621 and 751 ft just we cannot tell at which end the real life turning circle would be in fact.

Now if the same thump rule says the Hurri has a turning circle of 660 ft and we assume that also the error is 10% then the real turning circle of the Hurri can be expected to be in between 594ft and 726ft. Again we cannot tell at which end the real life turning circle of a Hurri would be in fact.

So it is absolutely conceivable just from judging the numbers and an assumed error of 10% that the real life Hurri could have had a larger turning circle than the Spit. Or vice versa.

Because the assumed error of 10% is larger than the calculated difference between both planes. Indeed from my engineering experience the error will rather be bigger than smaller. 10% error would be actually quite good. Even aerodynamic coefficients calculated with highly sophisticated numerical methods using finite element methods can be subjected to an error of that order of magnitude with respect to wind tunnel tests and 5% have to be considered as really good.

So basically the numbers as given by Mr. Bungay have to be taken very carefully.

[CaptainDoggles]

Stormcrow is correct; analyses are only as good as the assumptions made in their formulation.

[TomcatViP]

You misread me, Tom.

Seems so Crow. I understand now what you meant about the margin being to narrow regarding the precision of the model.

Sry for the induce bit of extra chatting ;-)