I am posting this as a follow-up to this thread 3 months ago which I failed to keep up with:
http://bbs.hitechcreations.com/smf/index.php/topic,286128.195.html A few of the relevant links:
http://img105.imageshack.us/img105/3950/pag20pl.jpg http://www.spitfireperformance.com/mustang/combat-reports/20-murrell-2dec44.jpg http://www.lonesentry.com/articles/ttt/russian-combat-fw190.html Most relevant to my comments here:
http://img30.imageshack.us/img30/4716/jjohnsononfw190.jpg http://bbs.hitechcreations.com/smf/index.php/topic,261798.0.html I felt the need to answer some of Badboy's assertions after I stopped following the thread, as I realize he had access to the full 1989 report while I had only ever read the "condensed" version.
First I want to point out something about his argument on the Johnny Johnson FW-190A vs SpitV account:
The "quotes" are from me with his answers:
Quote(Gaston)
I love the omission of Johnson's quote: "He was gaining on me (in the same ever decreasing circle, remember?):
-(Badboy)Nope, when Johnson noticed that the 190 was gaining on him it was while he was doing "the tightest of vertical turns" during the time they were whirling round on opposite sides of the circle, the fight was neutral. You are confusing the chronological sequence in Johnson's description.
Quote(Gaston)
(how could "an ever diminishing circle" be a bunch of vertical loops?)
-(Badboy)They were clearly different phases of the fight one followed after the other.
----OK: One phase of flight followed by another: This is the actual Johnny Johnson text:
"Then we both turned hard LEFT and whirled round on opposite sides of what seemed to be an ever decreasing circle. With wide-open throttles I held the Spitfire V in the tightest of vertical turns"
So the SECOND sentence here is supposed to be a transition to vertical flight.... ("Vertical Turn" was in fact a widely-used WWII lingo for "Vertical Bank Turn")
The following sentences drives the point home:
"Where was this German, who should, according to my reckoning, be filling the gunsight? I could not see him, and little wonder, for he was gaining on me, and IN ANOTHER COUPLE OF TURNS, he would have me in his sights."
I think this can go without comment as to the likelyhood of a series of vertical loops...
Then we can start with the 1989 "Society of experimental test pilots" test comments, which point out a 6G "Corner Speed" at around 320 MPH at METO (thus blowing away, conclusively in my view, any claims for this to be at 2.44 stall; 240-250 MPH).
This is what Badboy says about this, having access to the full report:
"The 3G accelerated stall tests were conducted in a descending turn, which explains why that data point appears where it does, but the speed quoted for the 6G corner velocity is too high. If you examine the data points on the stall speed curve, only the first 3 points correspond to the stalling AoA and lift coefficient for the 1G power on stall speed. Those first 3 points go up to 3G, after 3G, the line indicates that the test pilot was pulling to a point below maximum AoA and was therefore at a lower lift coefficient than he was achieving at the lower G values.
It appears that only 3G accelerated stalls were conducted during those tests and there is a clue in the report as to why that might be. It says that the P-51D they tested had "High Stick Forces, Inadequate stall warning, and Vicious departure characteristics" If the pilot were to allow the stall to fully develop, there was a real risk of exceeding structural limits and spinning the aircraft. Power-on spins were prohibited, because they were (and still are) considered very high risk. Recovery could take as much as 10,000 feet, but these tests were carried out at 10,000 feet, so it is clear that while the pilot was reaching 6G, it was not at the 6G accelerated stall speed, because the resulting "vicious departure" may have overloaded the airframe and left the pilot without enough room for recovery. Not to mention that during departure the rapid onset of normal and lateral forces on the pilot would cause blackouts much more rapidly than the slow G onset normally commanded by the pilot in the approach to the stall, thereby increasing the risk. So the pilot who conducted this test was actually reaching 6G at a speed above the 6G accelerated stall speed for safety reasons, and this was therefore not the true corner velocity. This can also be confirmed by inspection of FIG 10 from this report, when superimposed on curves of what would have been aerodynamically possible. In each case, the pilot gave himself a safety margin and did not reach the 6G accelerated stall that is normally quoted as the Corner Velocity, and instead recorded a higher speed where the 6G limit was reached. That margin in the case of the P-51D test was 34 KIAS above the speed at which a departure would have occurred.
Given that the 1G stall speed and the Corner Speed occur at the maximum lift coefficient, the Corner Speed based on the 1G power-on stall speed of 83 KIAS as stated in Table II and Figure 9 of that report would actually result in a Corner Velocity of 203 KIAS, and a top speed of 300 KIAS for a WWII P-51D at 10k and full military power. That tells a very different story.
Yes, the report was right to state that the corner velocity was close to top speed, but only under the conditions used in the test. Those conditions were of a fighter being flown below full power and thus achieving a top speed well below what it was capable of, and being pulled to 6G at a speed above the 6G stall speed for safety reasons, and thus not achieving its true corner velocity at the 6G accelerated stall. "
---First of all, I have always heard that power level has no effect on the position of the "Corner Speed", so in that context why the power level used here is significant to the absolute CS speed value is beyond me...
-Second, no allowance is made here that the "Corner Speed" could be "pushed" even higher with more power (a strong suspicion of mine since the modest METO setting already was already enough to push "Corner Speed" a gigantic 80 MPH above the expected 240 MPH value)...
-Third,
the 6G "Corner Speed" is speculated by Badboy to be somewhat less than the "Real thing", because of fear of stalling, yet pilots point out they limited themselves to 6Gs instead of the full 7Gs, and they do describe the stalls, which shows that they DID go as far as stalling the aircrafts (describing an occasional full inversion on the P-51D's stalling). Nothing prevented them from flying higher anyway if they needed more room to recover...
The pilots did not mention that the "Corner Speed" they described was anything less than the real thing, so it would be more resonable to stick with what they actually stated, which is exactly what I claimed all along: The "Corner Speed" in most of these crates is way too high to be worth "downthrottling" to, particularly when no upthrottling ever follows...
Finally I would like to point out an example on how the wing's position relative to the prop can have large unpredictable effects on performance, which makes it impossible to predict turn performance with just simplistic math formulations: Anyone can compare the following to the multiplicity of math-based game "speculations", that bear no relationship to reality:
Flight journal "Pacific fighters" collector edition 2010, p.74,:
"(On the N1K1, 1001 of near 1500 "George" built) It was probably faster than the Hellcat (It was vs -3s: N1K1: 650 km/h), but the turning performance and maneuverability were not very good. If you were rough with the stick, you could go into what the pilots called "autorotation". During this movement the aircraft would go out of control, or sometimes, it went into a spin. It turned in a way the pilot could not predict. For example, during an aerial melee over Manila with US fighters, a squadron mate of mine went into autorotation when our unit engaged them. His aircraft then went into a spin and crashed into the ground. In autorotation, you do not know what will happen, whether you will go into a spin, or flip over. It is totally unpredictable.
On the flaps: "They worked very well, however, in spite of them, handling the plane was still a problem. The combat flaps worked well in tight turns, and they would work smoothly. But, there were still handling problems with the aircraft. Ryoichi Yamada"
-These problems were apparently much reduced, or absent, on the low-wing N1K2.
If there is an N1K1 in "Aces high", you can see how an inferior maneuverability to US types is certainly not what the math would predict... As one of the few mid-wing single engine monoplane fighters of WWII, one can see how even a few inches of wing position can change a lot of things, and the math predicts none of this...
Same with the Japanese's extensive, and prolonged, testing that concluded one Ki-100 could take on 3 Ki-84s in a dogfight and still have a good chance to win, to the point each of the Ki-84 pilots could repeat the same by switching aircraft...
So you really have to look beyond maths to get a meaningful picture...
Gaston
