Here is the cut and paste quote, hitech (It is the "Society of Experimental Test Pilots", I remembered their name wrong):
"SUSTAINED TURN PERFORMANCE at METO at 10,000 ft.
The F6F out-turned the other three by a conclusive margin (1g). The other
three were all about the same.
Corner speeds of all were very close to the maximum level flight speed,
implying very rapid energy loss when turning at the structural limit.
The F6F was in light airframe buffet at 6g at Vmax; the P-47 experienced
light buffet at 4.8g. The FG-1 and P-51 were buffet-free up to 6g."
This test here was limited to 6Gs... I asked an actual prop aircraft designer, and he did not find it implausible that the "Corner Speed" would be that high ("Very close" can only be above 300 MPH, and is likely as high as 330+)...
If you can pull high Gs (5 G +) below 300 MPH, it could simply mean the "Corner Speed" is a modest 6 G peak at 330-350...
Note the same holds true of the other three US WWII types, and is likely true on many WWII fighters, including the Bf-109F/G/K if trimmed tail-heavy... I am almost sure it would not apply to those types with very poor high-speed elevator performance, like the A6M Zero, or it would "seem" to be even higher on the FW-190A, well above 400 MPH, because its turn/pull-out performance is so poor between 250 and 400 MPH... [Even then, measuring Gs on the FW-190A, at very high speeds, is a questionable issue because of the steep nose-up deceleration mushing (IE: The "tendency to black-out the pilot" mentionned in the Italian Front P-47 comparative)...:
http://img105.imageshack.us/img105/3950/pag20pl.jpg That is why it was NOT used for Boom and Zoom in Russian-observed Luftwaffe tactics, but the Bf-109G emphatically was... "The principal characteristic of the Me-109 in combat was speed", said French ace Clostermann, while comparing it to the FW-190A... ("Le Grand Cirque", comparative footnotes at the end) You have to wonder why it was not so for the actually faster FW-190A... What did he say about the FW-190A?: "They started later in the war to use flaps to turn a little tighter" Hmmmmm... but I disgress...]
Quote, Karnak: "WWII aircraft did not produce enough thrust at full throttle to reach their best turn rate as a sustained turn. That is why the Bf109's (not sure which version, but even from a D to a K the number won't go up too much) best sustained turn speed is 160mph and the best turn rate is 220mph. Turning that hard produces too much drag for the Bf109 to reach 220mph. This is true of all WWII aircraft for whatever their best turn and best sustained turn speeds are. All decreasing the throttle is going to do is slow the aircraft down and force the pilot to slacken off on his turn in order to dedicate more of the wing's lift to keeping the aircraft at its altitude, thus increasing the radius of the turn as well."
-160 MPH is barely 55-60 MPH above stall... Where is the source that 160 MPH is the Me-109G-6's best sustained turn speed at FULL power? Karhila mentions it stricktly in the context of
downthrottling, something he emphasizes not every pilot did...
Besides, it is obvious from the "Society of Experimental Test Pilots", since the Me-109G's elevator, with tail-heavy trim, could beat a WWII-vintage fabric-elevator P-51D Mustang's above 400 MPH, that the Me-109G's "Corner Speed" is more like a P-51D's than an A6M Zero's... Lowest speed to reach 6 Gs for a Me-109G was likely more in the (tested) Mustang neighborhood of 320-350 than the Zero's likely 200-250 MPH range... The 2.44 stall/Corner Speed ratio for these WWII fighters, at least if METO is used (and I do think METO power also affects the instantaneous turn), does
not appear to correspond to actual tests... I would rather go with the test than with "all aircrafts are the same at a 2.44 ratio"...
Quote, PJ_Godzilla: "Nothing is moving backwards. All you're doing with the pitch rotation is slightly decreasing the forward velocity of the upper part of the prop, thus changing its local alpha and slightly increasing its thrust there. I suppose what you say would be true if the ac were fixed but it's not. Even if it were, so long as the line of thrust is aligned to the pivot point, the resultant pitch moment from the pitch perturbation would still be zero."
-First of all, the thrust alignment is NEVER perfectly in-line with the pivot point... In WWII fighters it is nearly always above...
-YES the nose lifted IS moving backwards compared to the INITIAL straight-line situation, just like the tail IS moving forward... This is NOT the case sometimes if you don't have to pull back on the stick: The aircraft "tightens" the turn by itself for aerodynamic lift reasons... As soon as you have to keep pulling back on the stick, it means the aircraft wants to go straighter than what you want it to do... And THAT "straighter" direction, which the aircraft "wants", is the fixed reference point from which the nose moves back and the tail moves forward as you pull for what YOU want... And that fixed reference line continues fighting you as long as you need to deflect the elevator...
Now that we have the basic concept that, compared to the direction the aircraft "wants", the nose DOES move backward on stick pull, as does the tail move forward, we can adress why the rotation of propulsion thrust pitch at the rear is not the same as the rotation of traction thrust pitch at the front: Allow me a few questions to see if you actually visualize the concept:
What is inherently more stable, pulling a wheelbarrow or pushing it? Isn't greater stability in a aircraft a greater RESISTANCE to turning?
If you exclude propeller torque effects: Is the process of being tracted at a lower speed, compared to what the
current engine output would allow, not increasing that "wanting to go straighter" stability effect, as long as the speed remains slower than the maximum straight line speed for that power output?
Finally, perhaps more cryptically: What happens when you cut wood with the tip of chainsaw? It does relate to why the propulsing tail moving forward is not the same as the tracting nose moving back...
Gaston
