-To Angus; I'm afraid there is no more data on the P-51D vs 109G combat I described, but it should be noted that the P-51D was noticeably slower in top speed in the dive than the B/C models, and all U.S. pilots were well aware of it, despite some apparent lack of "official" warning about the actual extent of the loss... So the margin in speed would have been much smaller vs the 109, especially if the "G-6" was a smoother later G-6/14AS model... In addition, at higher altitudes, the porpoising effect of the bubble top Mach number had an effect closer to 30MPH in speed reduction or maybe more... Also the chase could go on a long time because at higher altitudes the initial acceleration in the dive of the 109 was apparently noticeably greater, which would give it a sort of head start.
The B model was substantially faster in the dive, but was subject to unpredictable failures throughout its airframe; wings, tail etc... So it is not clear to me how much of that extra performance was actually used. Despite an "on paper" parity, the P-47 was much more esteemed by U.S. pilots in the dive...
As for the 109 versus Spitfires pull-out, note that the critical aspect is whether or not the tail-heavy tailplane trim was used. Numerous German pilots confess later in interviews that they did not use this feature when it could have made a huge difference. One of the top Finnish ace described almost going into the ground, and when asked about the trimmer, he had to admit he was so caught up in the action he did not even think of it... Also, the trimmer had to be used early in the dive or it became too hard.
It was an unnatural device to use, and, if pre-set tail-heavy, required the pilot to push constantly on the stick to maintain level flight, probably at a cost in speed too. This would probably also rob some of the great initial dive acceleration of the 109, which was a tempting but ultimately fruitless tactic against U.S. fighters. One U.S. pilot said; "They would keep diving; they never seemed to learn".
-To Murdr; Quote; "180° in 13 sec. at 400 km/h. This is only about a 2.9g turn. .... 100° in 14 sec. at 450 km/h is less than 2gs...NOT a maximum-rate turn."
If you take into account that the second part of the 360° would be done at a slightly slower speed, thus at a slightly higher turn rate, it is not unreasonable to say that this is a 22-24 sec. 360° turn. Even at the full 26 seconds, this is almost an exact match to Russian tests that pegged the 360° turn rate of a G-2 at 20-21 seconds and of a G-6 at 22-24 sec., speed unspecified. A rate of 15°/second does seem low compared to a roll rate of 80° sec, but not out of line with film footage... If they can do 30° sec. for a full 360°, then I would be interested to see the data. My impression of WWII footage is that they are all surprisingly slow in turns, but if a 10 sec. 360° is possible, then I definitely want to know...
A doubling from a conservative turn rate, seems logical, but if peak turn rates are supposed to be much higher than this, then pulling 4Gs would require according to you a 360° circle completed in 10 sec. I've never seen such a figure, but that doesn't make it impossible. My impression is that pilots did not suffer greatly from continuous Gs at 400 km/h, but briefly suffered at 500 km/h and above...
Even the Yak-3 could do no better than 18 sec., so if a 26 sec. 360° at 400km /h to 50 sec. 360° at 450 km/h is a drop in the sustained turn rate, it must be entirely due to a lack of acceleration power in the engine above 400 km/h; possible, but sudden and large?
Yes, Mark Hanna mentions 5 Gs at much higher speeds, but notice that the elevator authority over the 109's attitude is always good.
Gunther Rall (109G-6, NOT the P-39 collision); "I was going down too fast and pulled on the stick to avoid him, the aircraft responded nose-up but despite this kept going down. There was a terrific crash..." I do remember this was NOT a prolonged dive, but a very short one.
This is just like the 190 tests with Kurt Tank's x(7?)Gs per Kilo of stick pull at very high dive speeds; impressive-sounding, but what if it was for a mere one second? Mark Hanna does not say how long these 5Gs were sustained, and we know even less about how the 109's trajectory responded. If sustained then it would indeed mean I am wrong about the 109 performance "hole". It is a "hole" in sustained turns only then, due to a fall-off in engine acceleration?
This "hole" in peak turning performance as I "see" it would explain why the 109 is often portrayed in U.S. combat reports as slower turning than the 190, when Russians reports rave about the 109's turning ability and berate the 190; U.S. fighters could keep the speed just high enough to spend most of the turning combat in the worst possible zone of 250-280 MPH, where even the 190 had no such "falling off the cliff" in its turn rate.
In another issue, the notion that the 190 has great pull-out and turn performance in prolonged high speed dives has NEVER been verified/described in any test and combat report I have ever seen. Even Eric Brown's highly favorable view of the 190 underlines politely the "tactical restriction in pull-out from low-level dives". In other words, a truly superior diver as long as the ground is really far away...
As for the Me-163B issue, Rudy Opitz mentions in an old article that at 15000 ft., or so, the climb rate was at a given value, while at an altitude of a mere 10000 ft. more, the climb rate increased by 40 or so %. Sorry about the exact figures, but my game's Data Cards are designed for play... Yes the weight in fuel diminished, but the moderate acceleration described as "surprisingly slow" at low altitudes became so ferocious at higher altitudes that the warning for Mach overspeed had to be changed THREE times, from a blinking light, to a light with buzzer, to a light higher in viewpoint, with a LOUD buzzer(Opitz)... In "Warplanes of the Luftwaffe", p.226, the acceleration at the top of the climb is described as 250 MPH to 600 MPH "in seconds", while I have seen at least one reference to the high altitude power being equivalent to 9000 hp...
On another subject, here is the Lockeed roll rate chart of the boosted-aileron P-38L;
http://home.att.net/~ww2aviation/P-38rollchart.JPG It does illustrate my point about unpredictable performance. Sadly, there is so much incomplete info on so many of these aircrafts, that especially on the axis side (most particularly the Japanese!) some significant features will remain forever obscure...
I will try again to find those 1990s P-47/P-51/F4U/F6F tests, as I have found them to be very significant, but at the time (long ago!) I could only jot down the info... These however did NOT specify the exact peak of the P-51/P-47's turn rate, but I am sure now the actual sentence was "surprisingly,...quite close to the max. level speed." I would agree this cannot mean anything close to 400 MPH, but at the very least it does suggest something more than 300 MPH, especially when combined with the poor rating they gave the P-51 for sustained turning combat. Note that many official documents of the time, with smooth progressive curves, turn out to be calculated even when no mention is made anywhere of this...
As Socrates said; "The only thing I know is that I know nothing!"
Gaston.
