The speed figures were offhand, but not too far off. I should have remembered the LF Spit IX was 650 km/h. It is the LF I intended to use as an example; +18lbs vs +25lbs...
The Me-109K speed is likely that of a MW-50 equipped version, which is a bit biased, as I think after the summer of '44 MW-50 boost became rare in Me-109 units. So rare in fact, that I know of two late war anectodes of FW-190As landing at Me-109 airstrips, and then being abandoned there because not one drop of the necessary C-3 fuel was available to move them... Without MW-50, 109s could use the lower octane B4, but the 190A HAD to use C-3.
Without MW-50, the 109K could probably do only 705 km/h or 710 km/h. It did have something called MW-30 that could combine with B4 fuel, but apparently the pilots were so inclined for the MW-30 tank to be used for regular fuel, that they often set the switch wrong and flooded the engine! The point I wanted to illustrate is that with a nearly identical airframe, with the same glycol rads but an improved oil cooler, the radiator drag was efficient enough to allow an increase in horsepower to be converted to extra absolute level speed, something totally missing from the Mk IX or even the P-51, but at least the P-51's speed limit was much higher to begin with.
I find the lack of absolute level speed increase with extra power very interesting in these two allied fighters, while their speed and climb gains below critical altitude are curiously large... Is this a peculiar characteristic of a highly boosted Merlin engine?
In any case, the Spitfire XIV was a near total redesign compared to the more modest Me-109K...
The point made by rshubert about the Mustang's weight is perfectly valid, and is in fact essential.
The Mustang radiator did not allow superior performance in absolute terms, but it allowed very good performance at high weights.
The extra weight allowed greater loitering time. And this long loitering time was catastrophic for the Luftwaffe, as even the Me-262 could fall victims to loafing Mustangs that knew where it had to come back. They didn't even have to risk staying within the base's flak reach.
This is the soccer equivalent of waiting around the net to kick the ball in, which is why this and other games have the "offside" rule, if I may be allowed this non-sport expert comparison...
The 109K could match or beat the P-51D in combat, I even think it had more than parity, but the fact that the P-51 could out-loiter it and then match it over its own territory, despite a 6 hour+ round trip, shows the real technological advance of the P-51's radiator. Despite the weight of fuel necessary for returning to England, the P-51 could perform and accelerate as though it was lighter, although not tighter-turning at many if not most speeds...
The radiator advantages did not apply directly to the turn rate, which was not comparatively very good except at very high speeds, (ie; at some speeds actually worse than a G-6 w/o gondolas), but it could somehow compensate for that by accelerating more in a wider turn, "gaining" from the outside, forcing a fast 109G-6 into a downward spiral, and tilting or swinging the nose inward at the last second to gain lead to fire (The flaps do seem to provide a significant, if brief, turn rate gain at some speeds). In the Mike Williams "P-51 encounters" collection, one pilot describes doing this to a 109G, and briefly stalling SIX times, each time he "swung" the nose in for lead, before finally scoring the first hits... I think this was another one of those fifteen minutes twelve rounders that practically never occur in a P-47 vs 109G match...
A FW-190A is in a similar predicament as the 109G against the P-51 at high speeds, except that its turn rate at these higher speeds would not match the P-51 for a very long time, even with the help of a downward spiral. A long high speed battle would probably have to include many roll reversals. One actual Western Front FW-190A-8 ace on these boards was quoted as saying that preparing for battle with P-51s was done by downthrottling the speed and popping the flaps for low speed BEFORE the merge, either to set up a series of head-to-heads, or for stall fighting. Quite eye-opening. He describes out-turning and dispatching a tailing P-51D in two 360° turns at low speed...
Later in the war, 109G-10s and K-4s for the first time really matched, or "out-turned", the P-51 without spiraling down, strictly because of greater engine acceleration. They otherwise did not turn any tighter than the G-6.
You never hear anything like this with the paddle-blade P-47 vs 109G contest... On the contrary, the problem with the 109G, for the P-47, is that the P-47 often turns inside a little too much and starts to overrun too close, losing the target under the cowl. Except at high speeds, the P-47 has much more parity, or trouble, with the 190A, and this gets noticeably worse towards late '44. It also seems the later bubble top Jug is much heavier than the Razorback, and is not as good a dogfighter. I don't know what the exact weights are, but there might be a significant difference, and again greater engine power might have allowed a larger but faster circle to muddy things up...
As for the 109G-6's qualities, note that it is *implied* in the above Russian 190 evaluation that the 109 likes vertical maneuvers better, and that it is less stereotyped in what it can do. Besides better altitude performance, I am sure the 109G without gondolas can out-turn the 190A at higher speeds, where the 190A can start harder but will mush and lose speed more rapidly. At these higher speeds, the 109G-6 still loses more speed than a Mustang, and has to spiral down. At lower speeds it supposedly can out-spiral climb the Mustang (Steinhoff), but examples of this appear rare... The two German fighters do complement one another in many ways, as Rall said.
Note that I am as puzzled as anyone here as to why the P-47D and FW-190A can decisively out-turn my favourite, the Me-109G! This at different, but large, ranges of speeds... See the allied test below to see which one does which;
http://img105.imageshack.us/img105/3950/pag20pl.jpg Note that U.S. Navy tests on the Mike Williams site do appear to contradict some of the above test and statements, with a fully dismantled 190F ballasted as an A-5, that never worked properly when it was reassembled... This Navy tests was actually officially contested by the British Farnborough test establishement as to the roll rate conclusions, which roll rate on the 190 affects greatly low speed turn performance ("catching" the stall etc..). Also the F6F and the F4U are likely better turn fighters than the P-51 or P-47...
As to why can a P-51 can out-accelerate a 109G-6 while in a slightly or significantly wider turn, but not while climbing, I have no real clue either. Isn't acceleration the same in all directions?
I know much of this is not widely accepted, to put it mildly, but I really wonder just how well do we know these machines, when for instance a 1989 warbird flight test by seasoned test pilots yields results very much at odds with most previous "knowledge", especially concerning the P-51;
http://bbs.hitechcreations.com/smf/index.php/topic,261798.0.html Here is the thread I started on this issue;
http://bbs.hitechcreations.com/smf/index.php/topic,263700.0.html For another example of surprises, pick up the next August issue "Model Aircraft Monthly", and see, with photos and drawings, my letter on how "experts" have missed a fully redesigned 8" shorter tail on 5000+ Zeroes...
Even the Zero's chief designer, Jiro Horikoshi, makes absolutely no mention of this in his biography "Eagles of Mitsubishi". I think it is likely he didn't even know what Nakajima did with "his" aircraft...
I tell you, sometimes, we are more in the dark than we think...
Gaston
