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If Mach 1 is reached the engines will stall and with the reduction in thrust as well as the rapidly increasing air density as well as the increasing local speed, the a/c will quickly drop to below critical Mach and regain elevator authority for recovery. (though if the tailplane is already retrimmed to counter the pitch-down, when speed drops below ~.86 mach the a/c will already want to pich up with neutral elevator)
Waynos,
Let's get something clear here, the 1945-46 tests didn't establish that airframe couldn't take the stresses of a Mach 1 dive, all they did was conclude that at above Mach 0.86 elevator control was lost. Remember these weren't straight down vertical dives.
The comment about the Spitfire being "readialy controlled at this speed" doesn't make sense.
If the spitfire genuinely could dive to such speeds, it they would be terminal dives, not controlled ones. (as would the .89 Mach dive) It would be well above critical mach and the elevator would be ineffective. (rudder and ailerons may still be functional)
Now, the Spitfire may have gotten luck, and was inherantly stable above critical Mach, but that's a different issue. Also, to avoid structural damage to the airframe at such speeds, buffeting must have been relatively minimal, or the speeds were only maintained for very short periods of time. (the vibrations and flexing from buffeting can cause damage independantly of -G or stress directly related to the high speed flow)
I aint talking down to you Waynos, I'm just telling you that the tests didn't conclude anything about the Me-262's airframe not being able to take the stresses of a Mach 1 dive. And the airframe could take it as established in studies done in 1999. The problem was the pitching down above 0.86 Mach, something which could only be corrected by use of horizontal stabilizer trim, which I have heard the British weren't aware of, I think Hohun knows about this.
There are no miracles in physics mate, all things in aero can be measured, just like your sig lets us know.
If true regarding the slab elevator being blanked out in turbulent flow, how did elevator trim work to solve the problem. If there is no laminar flow over the elevator, there is nothing for the trim tab to work on.
If the issue was not turbulent flow but compressibility initiation over the elevator, the movable and boosted 262 elevator would have worked fine.
If it was the shock wave moving the Cp aft to ~ 50% Chord over the wing, causing a pitch down moment but elevator still in flow (i.e not blanked) then the elevator would still work and no trim required.
Which case for the 262?
I can well believe that the speed reading was not entirely accurate but there is little doubt that at least m0.9 was reached and no doubt at all that it was the fastest diving aircraft of the 2nd world war (er, except the V-2 I suppose). This much was proven with real aircraft on actual flight tests.
.If mathematical theory 'proved' the idea that the 262 could withstand mach 1 in 1999, why did Willy Messerschmitt support the RAE findings? wouldn't he have published the opposite view, at some point if not immediately? but he never did and even the intended 'high speed' HG.III model was not tested beyond mach 0.86 in any wind tunnel
Bill,
You're missing the fact that the entire horizontal stabilizer was movable on the Me-262 and was used for trim.
Jeff Quill