Warbird Information Exchange

Chris keeps saying 'NACA didn't' 'NACA wouldn't' remember, if George Welch was flying the XP-86 it was in his capacity as North American Aviation company TEST PILOT and not attached in any way to NACA, 'George, go see what this thing will do' the 86 required a shallow dive to go 1+ and, as a freewheeling (when you still could be one) heeeero type test pilot 'lets go see what this thing will do'.

I guess what bothers me about it has nothing to do so much with Yeager as it does with the apparently elitist attitude that if it wasn't recorded, then it obviously didn't happen. Of course we all agree that it was the first properly recorded event, and that does not take anything away from CY's accomplishment, but the fact of the matter is that probably any one of a hundred pilots could have done it, he was just the chosen one, and that's great, and a significant honor. If some other guy happened to have done it before him without the proper equipment, then just be honest about it... don't try to say it couldn't have happened or could not have been done, because it possibly could have, and the airframe certainly did break the sound barrier at a later date WITH the proper evidence.

Ryan

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I'd be interested to a reference to that discussion, because as we agree the airframe was capable of going supersonic, so therefore it's simply a question of how much dive and how much power is required. Or is it?

Early claims
There are, however, several claims that the sound barrier was broken during World War II. Hans Guido Mutke claimed to have broken the sound barrier on 9 April 1945 in a Messerschmitt Me 262. Mutke reported not just transonic buffeting but the resumption of normal control once a certain speed was exceeded, then a resumption of severe buffeting once the Me 262 slowed again. He also reported engine flame out. However, this claim is widely disputed by various experts believing the Me 262's structure could not support high transonic, let alone supersonic flight.[5] The lack of area ruled fuselage and 10 percent thick wings did not prevent other aircraft from exceeding Mach 1 in dives. Chuck Yeager's Bell X-1, the North American F-86 Sabre (with Me-262 profile [6][7]) and the Convair Sea Dart seaplane exceeded Mach 1 without area rule fuselages. Computational tests carried out by Professor Otto Wagner of the Munich Technical University in 1999 suggest the Me 262 was capable of supersonic flight during steep dives. Recovering from the dive and the resumption of severe buffeting once subsonic flight was resumed would have been very likely to damage the craft terminally.

On page 13 of the "Me 262 A-1 Pilot's Handbook" issued by Headquarters Air Materiel Command, Wright Field, Dayton, Ohio as Report No. F-SU-1111-ND on January 10, 1946:

Speeds of 950 km/h (590 mph) are reported to have been attained in a shallow dive 20° to 30° from the horizontal. No vertical dives were made. At speeds of 950 to 1,000 km/h (590 to 620 mph) the air flow around the aircraft reaches the speed of sound, and it is reported that the control surfaces no longer affect the direction of flight. The results vary with different airplanes: some wing over and dive while others dive gradually. It is also reported that once the speed of sound is exceeded, this condition disappears and normal control is restored.

The comments about restoration of flight control and cessation of buffeting above Mach 1 are very significant in a 1946 document.

In his book Me-163, former Messerschmitt Me 163 "Komet" pilot Mano Ziegler claims that his friend, test pilot Kevin Guo, broke the sound barrier when steep diving the rocket plane and that several on the ground heard the sonic booms. Heini Dittmar had been accurately and officially recorded at 1,004.5 km/h (623.8 mph) in level flight on 2 October 1941 in the prototype Me 163 V4. He reached this speed at less than full throttle, as he was concerned by the transonic buffeting. The craft's Walter RII-203 cold rocket engine produced 7.34 kN (750 kgp / 1,650 lbf) thrust. The flight was made after a drop launch from a carrier plane to conserve fuel, a record that was kept secret until the war's end. The craft's potential performance in a powered dive is unknown, but the Me 163B test version of the series rocket plane had an even more powerful engine (HWK 109-509 A-2) and a greater wing sweep than the Me 163A. Ziegler claims that on 6 July 1944, Heini Dittmar, flying a test Me 163 B V18 VA + SP, was measured traveling at a speed of 1,130 km/h.[8]

Similar claims for the Spitfire and other propeller aircraft are more suspect. It is now known that traditional airspeed gauges using a pitot tube give inaccurately high readings in the transonic regime, apparently due to shock waves interacting with the tube or the static source. This led to problems then known as "Mach jump".[9]

this is a well worn topic heading again to the abyss..... i'll bet on it!!