Gaston please learn to use correct terms.
1. the word optimal, simply means best. You are mixing 2 concepts.
2. You say "optimal turn speed", and ("optimal" sustained turn rate). They are completely different concepts. The key concept being the word SUSTAINED.
Every one here has given you the definition and why 160 is the best sustained turn rate. and 220 being the best turn rate , the key being able to hold the same speed and alt are the different between the concepts.
So the official terms would be best sustained turn rate. And best turn rate.I.E. Best turn rate & radius happen at corner speed. Best SUSTAINED turn rate & radius happen close to best climb speeds. Corner speed in AH (limited at 6 g's) happens at 2.44 * Stall speed. Corner speed happens at the sqrt(glimit) * Stall Speed.
now many people will leave out the word "Optimal or best" when speaking of sustained turn rates, it is automatically assume the word best or optimal is applied to the sentence or people would stat it more like what rate of climb or turn can be sustained in at 220 mph. But this is not the same concept of best sustained turn rate. It is the same concept when some one states the max speed of a plane, they are leaving out the part that it will only do this speed at one altitude.
If you were to try SUSTAIN a turn at 220 mph (this means not slowing down and not descending) you turn rate would be at least half of what your SUSTAINED turn rate would be sustained at 160 mph. And this is where you are constantly mixing terms. It is conceivable you could get a better turn rate and radius with reduced throttle at corner speed ( sorry I have not crunched the numbers to find out) but this will be at the expense of loosing altitude more quickly, notice we are not using the word SUSTAINED because this is not a sustained turn, we are loosing alt, and there fore will very quickly have to stop the turn, or hit the ground. Hence why the word SUSTAINED is used.
Now as far as you disk loading, could you please draw a simple sketch of this loading you are referring to? If you would I can fairly quickly do the math for you to show you it's net effect with full power and reduced power.
Gaston , it is obvious to me you are truly interested in these topics. I and a few others here know the physics side of this very well, and contrary to your belief, planes do not fly out side of the realm of physics. (If you do not except this concept of physics are true, your hole riser argument also falls apart, because you are trying to make a physics argument as to why the effect is there) If your "Disk riser concepts" is true, then your sketch would very quickly prove it to be true once we crunch some numbers.
HiTech
-The distinction between peak sustained and peak unsustained turns is very clear in my mind, and I do mention it always...
-I did not know that the best sustained turn speed of the Me-109G-6 was accepted as being 160 MPH: The replies I got on Il-2 was that the Me-109G-6 had a peak sustained turn rate speed of around 220 MPH, at full power, while the P-51D was a little higher at around 230 MPH. It is true Finnish testing of a Me-109G-2 "peak" at 220 MPH allowed some speed loss, but then the turn was done with a slight CLIMB, so the methodology is peculiar here...
In any case I had never heard of a peak sustained turn rate at FULL power being as low as 160 MPH before Karhila said so
for reduced power... Also I determined that the 6G "Corner Speed" of
many WWII prop fighters to be well above 320-340 MPH... This means to me that any downthrottling below near-full max level speed is not an advantage
according to accepted theory...
Note the Me-109G's pilot manual has the sustained turn rate, at full power and at 400 km/h, as being 13 seconds for 180°, or presumably a 26 seconds for a 360°: Very near the maximum sustained turn of 24 seconds in Russian tests, or 22 seconds for the G-2...
At 450 km/h, still in the Me-109G-6 pilot manual (a whopping 281 MPH), the sustained turn rate abruptly drops to 14 seconds for 100° of turning, so there is an abrupt sustained turn-rate drop of near-50% at a much higher speed than what you say... (I was told this was due to reduced engine acceleration, but I remain open for other contributing explanations for this abrupt drop: Prop disc load, aerodynamics)
If the sustained turn rate DOUBLED from 220 MPH to 160 MPH, then 24-26 seconds would be 12-13 seconds at 160 MPH... I have never seen such numbers for sustained turns below 200 MPH, or at ANY speed...
You say 6G "Corner Speed" is 2.44 time stall, but that would only be about 250 MPH on the P-51D Mustang, and wartime testing clearly has an unsustained turn radius of 450 yds (1350 ft.) at 400 MPH for the p-51D (Spit XIV 625 yds), and the 1989 P-51D tests also clearly states "(6G in test) Corner Speed is VERY close to maximum level speed", implying a rapid loss of speed when turning at this (6G?) "structural" limit" ("structural limit" might here mean something a bit higher, like an 7-8G Corner Speed at 400 MPH, which matches the wartime testing of 450 yds. radius at 400 MPH)
This means to me the lowest speed to be able to reach 6G unsustained, in a P-51D, is at
least around 320-350 MPH, and I don't see how this can be consistent with 250 MPH... The absolute structural max. of 7-8G is probaly around 400-420 MPH, which, with fluttering pushing the micro-second loads past 13 Gs, explains why these aircrafts could only be "broken" in dives, and never in level speed flight...
Also a 6G "Corner Speed" of 320-350 MPH seems consistent to me with a peak sustained turn rate of around 230 MPH at full power for a P-51D...
This matches, roughly, the Me-109G-6 pilot's manual 26 seconds of sustained 360°s at 250 MPH at full power... (Though the actual 24 seconds sustained "peak" was tested by the Russians at an unknown speed, maybe a bit lower like 220 MPH)
I am very surprised you find a sustained turn peak for the Me-109G-6 to be at 160 MPH, AT FULL POWER... My impression is that this is not consistent with the actual location of the 6G "Corner Speed" at 320-350 MPH in some types, and the near-best sustained 26 seconds sustained turn time at 250 MPH in the Me-109G-6 pilot's manuals...
In fact, my impression is that 160 MPH is such a low speed that the Me-109G-6 CANNOT turn hard enough to maintain such a low speed AT FULL POWER without downthrottling... It would be "pulled" faster to a more "natural" and wider-radiused sustained turn speed of over 210-220 MPH at full power... Top speed at full power is 400 MPH, or 360 MPH at lower alts: Can it really turn hard enough at
full power, at a
sustained 160 MPH, to lose 200 +MPH of straight speed???
As far as downthrottling accounts go, the notion that this tactic entails a loss of altitude is contrary to the examples I provided of this occurring in flat turns, or at less than 500 ft... I also pointed out that spiraling down to gain angles on a chaser is not a generally sound and acceptable tactic in WWII, since even out-turning in this case is useless because of the lower resulting position compared to the chaser... This is "giving up the high ground", and not really productive at low speeds where zooming or even raising the nose is not easy or available...
I will provide later some crude graphics about the disc load effect on wing-loading, since my worded explanations are not so helpful...
Gaston