Guys, I found something interesting in the previous article I mentioned (with the riveted elevator tabs)
Gas Turbines Also, on the tabs, it turns out this article is based on US captured examples of Me 262's.
But in any case, (on pg 21 of the article) there's some very interesting info on the controls which largely explains the discrepancies in reports of the high speed characteristics. It seems early models had controls that became very stiff at ~500 mph, an extended stick was proposed to correct this. However, this doesn't apear to have ever been carried out; instead an additional large mass balance was fitted which seems to have solved the problem.
Also, I'll double check, but neither "stiff controls" or directional snaking were experienced in the Wright field test, in fact iirc it was praised for its stability at high speed. (in shallow dives) Snaking wasn't mentioned either iirc.
Read the report in Stormbirds Rising. I am too lazy to scan it after I typed much of it out for you and Soren a couple of days ago. Report extracts from F-TR-1133-ND, Feb 1947, 'Evaluation of the Me 262'. It is in Appendix C.
Specific reference to 'hunt at speeds above 350' and 'the handling characteristics were poor at all speeds above 350 mph' are contained in Section 3 Flight Characteristics, paragraph e.
Personally, based on Wendel's interrogation I believe that what the Wright Pat test pilots encountered was poor rigging on the rudder tabs as contrast with general and universal issues - save the aft cg problem when fully loaded with fuel. See Section 7 Flight, pg 4 in the Wendel Link regarding cg and consequences
Further read Lindner's debriefing contained in Appendix B. The Appendix B references report API (K) No/339/1945. Note that stiff controls only seem to be in effect in the dives as the a/c accelerates into Mcrit. I brought that up because of Soren's comment that 'it was light and responsive in all regimes' or words to that effect. This whole discussion about steadily increasing stick forces is what the Structural and Stab/Control debate has been all about.
Read the POH that Soren thoughtfully provided at the section on Take Off Weights and Balances, as well as the other link Soren posted from KapitanWendel. Both discuss yaw issues due to filling aft fuel tank and moving cg past 30%MAC. That is found in Section 2- Before Entering Pilot's Compartment, paragraph c. Center of Gravity and d. Take Off Weights and Balances for discussion of Yaw issues at aft Cg.
And Bill, in a straight down 90 degree dive, there will be no pitch down behaivor, so that wouldn't be an issue.
That is correct -it will reach a point of zero lift. The challenge is getting to that point KK, then the reverse occurs as you start the pull out.
Whether Mutke did it or not will never be proven.
The problems to be solved in a rigorous analytical study is first the entire aerodynamic load profile as the 262 enters the dive and accelerates past .8, and .86, then whatever speed provides a solution of transition from loaded wing and heavily loaded tail to unload on the wing and tail... then reverse the process. This includes study of the engine nacelle/fuselage shock wave interaction if it occurs as well as the inlet geometry for compressor behavior prediction. I would be looking at the wing spar (due to both aero load and inertia of the Jumo/nacelle combination) during pullout as well as tail attach points (due to severe aero loads to overcome CMac - transmitted to aft fuselage)
The second problem is the stability derivatives as the CMac increases during the transonic migration of the ac to .50 Chord - to point of no load on airfoil and look at this behavior during the transonic, to local supersonic, to complete supersonic - that is the cycle in which the ac moves from stable aircraft as designed to a forward cg condition in which the elevator experiences tremendous forces in very high 'Q'... all the way to Mach 1 - then back again during the pull out when the a/c slows back to transonic with a fully loaded tail structure. Is CMac derivative stable and predictable during the transition? If not - how does that translate to stick forces and stability in general?
The last problem is pure structural analysis, starting with the aero loads on the elevator, then transmitting them to the fuselage, as well as the wing discussion above. If there are no yaw loads during the transonic profile, then torsion transmitted to the aft fuselage stringer/beams will not be severe.
Soren, on the comparison to the Spitfire, in the dive trials, the Spit was fitted with al fully feathering prop to avoid overspeeding, minimise propeller related compressibility issues, and minimize drag experienced at high speed.
The Me 262 would indeed still have thrust available at speeds where the Spitfire will have none (though both will be relying mostly on their weight). However, when the air ingested by the engines reaches supersonic speed, they will stall and flame out. (as Mutke experienced iirc) At this point the a/c is relying entirely on its weight alone for thrust. (although the engines had only been providing ~15-18% total thrust in a vertical dive)
Also, I retract my statement about the Spitfire being necessarily terminal at .89 Mach. It would be above its wing's Mcrit (for all sections much greater than ~10%) but given the thin tailplane the elevator may very well be fenctional. Additionally, while "tuck" is usually experience when an a/c's wing's critical mach number is exceeded, this isn't always the case (ie F-84 does the exact opposite) and the extremety of this characteristic veries as well. Assuming there is a tuck, it may be weak enough to counter with the stick or (if controls are too heavy) trim.
Strictly speaking 'tuck' occurs when the movement from .25 c to .50 c can't be overcome by normal elevator controls. Having said that - moving the ac aft changes the CMac always.
The critical Mach of the Spitfire's root section is probably ~.8 and increases as it tapers outward. (at 10% it should be arround .9 Mach) Due to the thicker section, the P-51D probably initially exceeds Mcrit of the wing somewhere arround .7-.75 mach. (iirc the earlier P-51's wing was somewhat thinner in section, as was the P-51H's)