An interesting site I found...

Spitfire Mk XIV versus Me 109 G/K, A Performance Comparison

I posted this just a few days ago on the muddy and much misunderstood issue of relative turn performance (often very relevant to the myriad of Spit vs Me-109 debates)...:

The Me-109G was likely less maneuverable than most other fighters, especially in prolonged sustained turns, because it tended to bleed speed in level turns.. Spiralling down it did better, but that usually meant giving up on shooting the pursuer, since being below makes this near impossible...

The Me-109G was more of an Eastern Front fighter in late 1944: By then, 70% of Western Front fighters were FW-190As, which was more competitive in sustained turns vs the P-47D and P-51s... The FW-190A was simply better, period, and the Me-109G would have been phased out if the FW-190A had better handling at high altitudes above 21 000 ft, where the bombers were...

The Me-109G was best used on the vertical as a high speed dive and climb fighter, but was cornered into using the high speed spiral climb against the better vertical performance of higher flying US fighters, which could use their extra cruising altitude to negate the better Me-109G sustained climb by zooming up to it after diving... The Me-109G was a poor turn fighter that could barely match the P-51 in sustained turns, and had no hope at all in left turns vs the P-47 in prolonged turns...

The P-51 was very close to the Me-109G, but, by lowering the power and dropping its flaps, it could gain in sustained turns with the prop pitch set on coarse at lower speeds. :
http://www.spitfireperformance.com/mustang/combat-reports/339-hanseman-24may44.jpg

Maybe the Me-109G would again be close if it did the same, but, as I said, the Me-109G was actually more often used as a high speed vertical maneuvering fighter. "A Floret" in the words of Gunther Rall (which is a thin straight fencing sword)...

Sadly, there are many comparative tests done, mostly by the US and especially the US Navy, that appear to be unreliable and thus created a lot of confusion... For instance, the sustained turning ability of the P-47D, in actual real-life combat, was superior to both the P-51 and the Me-109G, even with its deceptively wider initial radius...

http://www.wwiiaircraftperformance.org/p-47/p-47-encounter-reports.html

The wider initial unsustained turn radius of the P-47 was apparently not weeded out most US sustained turn evaluations...

The FW-190A was yet another kettle of fish, and had poor high speed handling, especially to the right, but was the only mass-produced Luftwaffe fighter to out-match the P-47D in sustained turns, though not by much vs the early Razorback turning to the left. Again, the FW-190A had a wider initial radius of turn than a Spitfire, but if an immediate solid hit was not achieved by the British fighter (within around the first 360°), the Spitfire would then almost inevitably fall behind and be caught in level turns by the FW-190A...

The Spitfire was in fact not competitive at all with the FW-190A in sustained turns, in the words of Canadian Hurricane pilot John Weir... Many other British, Russian and German sources all confirm this, usually pointing out to precisely the same peculiar FW-190A handling features, like its poor tail-down "sinking" /"hanging" or wing-drop "snapping" high speed handling...

The FW-190D was less maneuverable in sustained turns than the A, but climbed better. One Allied pilot testing the D-9 in 1946 felt the loss of handling clearly was too great for the gains in performance...

The FW-190A was truly "it" on the Western Front, and was only limited by poor high altitude handling and dreadful high speed handling at any altitude, which made the Me-109G complementary when going high or fast...

In general, the actual performance relationship of all these famous fighters is shockingly misunderstood if my reading of thousands of actual combat accounts is any guide (1300 of them for the P-51 and P-47 can be found in one place if you google "Mike Williams WWII Aircraft Performance": I did read them all)... I know from discussing this with several Aeronautic engineers that they do not recognize the effect of nose length leverage and the slight thrust slanting (caused by the turn's curvature causing slight assymetrical thrust compression) to increase the wingload when the prop's thrust is beaten by tilting it back when changing the wing's angle of attack...

This adds easily around 30% to the entire wingload (1000 lbs in the upper prop disc goes up to 7-8 000 lbs of leverage resistance at the wing, on top of a 21 000 lbs total force for the Spit at 3 G), which is why reducing power (or a shorter nose) helps prolonged multiple 360° turning at low speed (and less at high speed 6 G turns, since still only 8000 lbs of prop force are now added over a 42 000 lbs total force) ... :http://www.spitfireperformance.com/mustang/combat-reports/339-hanseman-24may44.jpg

The nose location of the thrust is the basic cause of this, and this does not really apply to jets for obvious reasons, which is why the effect is still ignored...

Ignoring the P-38 and P-40, the two most able US and German turn fighters in the West in 1944 were the FW-190A and the P-47D... Again contrary to the usual dogma, boom and zoom fighting was more an Eastern front and Pacific Theater staple than a Western European one, especially in 1944-45...

According to Hurricane pilot John Weir, the Spitfire could not sustain turns with the Hurricane, and of course neither did the Me-109... He mentions however that the Hurricane could not escape the FW-190A in sustained turns...: "The FW-190s, those just kept coming you know..."

A point should be emphasized here: Both the P-47D and the FW-190A had wider INITIAL turn radiuses than the Spitfire of Me-109, but unlike current assumptions, unsustained turns at 6 Gs do not translate at all to sustained speed turn performance at 3 Gs...

Note how all Spitfire successes on the FW-190As are always within the first 360°... This was not a typical way to achieve successes with an average WWII-vintage hit rate of 2% of all shots fired... Firing 1/8th of the 360 radius, this average for the Spitfire meant two 20 mm hits and eight 7.7 mm hits per full 360° with the target under fire...

In prolonged sustained turns, the FW-190A was clearly better than the Spitfire, just as the P-47D was massively better than the Me-109G... The "Circus Rosarius" conclusion on a captured P-47D Razorback?: An unqualified "The P-47D out-turns our Bf-109G" (On Special Missions: KG 200). Also the 600 P-47 combat reports linked here show the German conclusion to be quite an understatement...

The Soviet evaluation of the FW-190A was equally clear: "The FW-190A inevitably offers turning combat at a minimum speed..." and "The FW-190A has better horizontal maneuverability compared to the Me-109"

Here are a few relevant links:

Soviet evaluation from actual combats: http://www.lonesentry.com/articles/ttt/russian-combat-fw190.html

-Squadron Leader Alan Deere, (Osprey Spit MkV aces 1941-45, Ch. 3, p. 2: "Never had I seen the Hun stay and fight it out as these Focke-Wulf pilots were doing... In Me-109s the Hun tactic had always followed the same pattern- a quick pass and away, sound tactics against Spitfires and their SUPERIOR TURNING CIRCLE. Not so these 190 pilots: They were full of confidence..."
(8 to 1 for the FW-190s that day...)

Johnny Johnson opinion of the FW-190 in combat, and his harrowing near death experience...:

http://img30.imageshack.us/img30/4716/jjohnsononfw190.jpg

Now understand the currently accepted math methodology says all these pilots of disparate nationalities have no idea what they are talking about...

It's up to you to consider if simplistic wingloading and power to weight equations are enough to prove all these people wrong...

Gaston