63 years ago today

[JDK]

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'.

And so what? It's not important it was NACA specifically, but that the flight was documented and recorded properly. Those NAA records would satisfy the 'first' claim nicely - oh, we don't have them.

There are also good reasons we don't have 'free wheeling' test pilots or the resultant lost prototypes and lives seeing 'what this thing can do' any more, thankfully. (Both canards, I believe, are not appropriate to Welch anyway.)

Regards,

[Clifford Bossie]

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

Ok, it is not "elitist" to expect proof when making a claim. It is up to the person making the claim to provide the proof to back the claim up. It is not up to someone else to prove that claimed did not happen. I can claim that aliens built the pyramids, or that dogs can fly, but it is incumbent on me provide proof for those to be taken seriously. It is not up to anyone else to disprove my "claim". You can claim that someone else broke the sound barrier prior to Yeager, but it is your responsibility to back up that claim with proof. As of now that claim is only an assertion.

As for the Germans breaking the sound barrier during WW II, that is highly unlikely. Neither the Me 163, nor the Me 262 seem to have had a high enough critical Mach number to allow transonic speed. Both seem to have been limited to somewhere around Mach .86.

Indicated airspeed was not reliable during WW II for a number of reasons, that is why there were fables at one time of P-47s exceeding 700 mph in dives. Without some form of tracking and data collection from the ground it would be hard to take seriously some of the speed claims made during the war.

History records Chuck Yeager as the first and until proof to the contrary is presented that history will remain.

[Zachary]

[

I don't think there is any doubt that the airframe did break the sound barrier at a later date, however, there is a pretty strong argument put forth by retired NASA/Air Force engineer Robert Kempel* that the XP-86 as first flown with the GE J35-C-3 could not have broken the sound barrier because the engine was not powerful enough to do the job.

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?

Robert Kempel has written a short book about this called "The Race for Mach 1: Who Was the Winner?" It it currently unpublished, but with any luck it will be published by HPM Publications in the near future. That being said, Kempel wrote a very informative article about this subject titled, "Mach 1 and the North American XP-86" that can be found in the Vol. 51 No. 1 Spring 2006 issue of AAHS Journal. (American Aviation Historical Society for those unfamiliar)

Zack

[Bill Greenwood]

I don't have the info in front of me, but I recall that Me 262, while very fast in level fight, 540 mph or so, did not have high mach critical speed close to Mach 1. It's ceiling was also only about 36,000 feet.

I don't know about the Me 163, but don't recall any stories of it over mach. The 163 rocket engine ran such a short time that it would be used up in a climd and they would not have dived with it.

The closest to mach one, the highest WWII dive speed that I have read about is MK XI Spitfires, which were test dove to mach .90 and .92 of the speed of sound. I think these were standard Spits, but with no armament. There was no airframe or handing problems, pretty good aerodynamic design for a guy who passed away before WW II and did not use computers. There were two these very high speed test fights, both times they had problems with the spinner backing plate and then the prop. In the first case the pilot was able to glide the successful landing , I an not sure of the 2nd case.

The first Me 262 kill of the war was by a Spitfire diving on the jet. I am certain if the Spit pilot saw a 262 attacking him, he could turn into and under him. You would not want to take any hits from the big cannon in the nose of the 262. I suppose the 262s were mainly going after the bombers and not wasting time on fighters.

[JDK]

My bold:

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]

http://en.wikipedia.org/wiki/Sound_barrier#Early_claims

Usual caveats apply, but all the items mentioned regarding Me 262, 163 and Supermarine Spitfires are well referenced. The 'Mach Jump' problem mentioned illustrates clearly why there were some honest but incorrect claims made (I'm not including the Wade case in that, though) and why accurate data was even more vital in this case than 'normal' speed claims.

IMHO, there were probably pilots who flew transonic during W.W.II, but didn't live to tell the tale.

Following Bill's Spitfire comments, which I agree with, broadly - one Spitfire claim IIRC, was a Merlin PR version (X or XI?) with the cleaner wing (no guns or bulges) that lost its propeller and reduction gear and may well have been briefly supersonic. The pilot pulled off a brilliant recovery and wheels-down dead-stick landing but the airframe was badly strained.

Regards,

[tom d. friedman]

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

[JDK]

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

Ummm...

Actually there's been some interesting discussion with some new data and insights brought in; but feel free to direct the discussion into the pointless channel.