On Monday 22 September 2003 at 14:32:09 UTC+10, Dan Shackelford wrote:
> On Sun, 21 Sep 2003 21:16:00 -0500, wrote:
> > I was watching the Discovery Channel program comparing the F-86 and Mig-15
> > and heard that the F-86 can break the sound barrier. I know that this has
> > been claimed many time before but is that the official position of the US
> > Air Force? Is Yeager still officially the first man to break the sound
> > barrier?
> No, George Welch was the first to exceed Mach 1 in a dive with the
> XP-86. See: http://home.att.net/~historyzone/Welch2.html
> I also have a better source, my father. He was part of the design team for
> the Sabre at North American and they were informed about this BEFORE
> Yeager broke the sound barrier. He had to keep mum on this for a long time
> though.

No unfortunately, with respect, this is a zombie myth and one that has been repeatedly examined in detail for over 60 years and found wanting. It's almost tiresome. This entire story rests on a single anecdote about Welch casually walking into an NA engineer's office after a flight and describing his experience with an increase in buffet that went away during a dive. This is exactly what happens when you dive at higher altitude (colder air-lower Mach number) and as you descend the air warms up, the speed of sound increases and you move further away from the buffet boundary. He also noticed a blip in his ASI, likely a result of localised disturbance as it had not been calibrated. The engineer responded:

"Looks like you might have been experiencing some Mach effects" or words to that effect.

This statement has then been taken and mythologised as proof of the first supersonic flight (not unlike a thoroughly discredited one by a ME-262 pilot) but anyone with any idea about aerodynamics knows that 'Mach effects' occur the minute an aircraft passes its critical Mach number. MCrit is when any part of an aircraft experiences localised supersonic flow, not when the aircraft is fully supersonic.

As an example, P-38s experience Mach buffet at 0.70. A PR Spitfire wing's Mcrit was mapped at M0.89 because of its very thin broad chord wing and in fact holds, to this day, a verified record for propeller driven aircraft during diving tests run by the Royal Aircraft Establishment in 1944 at Mach 0..92, but propellers don't like high Mach numbers and promptly departed the aircraft along with its reduction gearbox, resulting in an 11G pullup and a rather bent aircraft. But I digress.

The XP-86 was at an extremely early stage of testing, (the aircraft had flown just a handful of times) the aircraft was not instrumented, i.e. no trace recorders, no telemetry, the pitot/static system had not even been corrected for position error, there were no instruments to correct for OAT and therefore Mach number and to top it off, it had the low powered early Allison J35-C-3, a 3,750 lb thrust engine (1/2 the power the F-86 would have in the ultimate CAC 32 Avon Sabre version) Additionally, existing NA records show that it was conducting low and medium speed handling trials at the time. High speed testing came in 1948, in other words, it was not conducting the part of the flight envelope expansion that any sane aircraft manufacturer would accept as a suitable risk to a two week old aircraft, and the only one of its kind in existence.

If anyone can present authentic copies of NAA test program flight data from this date to say otherwise, i would be happy to see it but otherwise, it a just another zombie myth.

The F-86A set its first official world speed record of 671 miles per hour (1,080 km/h) (on September 15, 1948, at Muroc Dry Lake, flown by Major Richard L. Johnson, USAF. It is not clear if this was a supersonic flight as altitude is not given. If this was at 10,000' on an ISA+10 day (being Muroc in September) that makes Mach 1.02 but this is very unlikely unless it was a dive. As far as I am aware FIA only awards records in level flight flown in 2 directions within 1 hour. In level flight at 5,000 ISA +15, that would be M 0.952

By late 1948 USAF pilots were having all kinds of fun booming crowds in F-86s but this was with full production, fully tested and higher powered aircraft...

"Complete Aerogeek" wrote in message
news:7ba053af-5151-4b6c-a6e9-0e815263ad86n@googlegroups.com...

>If anyone can present authentic copies of NAA test program flight data
>from this date to say otherwise, i would be happy to see it but otherwise,
>it a just another zombie myth.

Here's a possible lead:

https://plane-encyclopedia.com/cold-war/north-american-xp-86/
"North American test crews heard about this feat through rumors and
persuaded NACA to use its equipment to track the XP-86 in a high-speed dive
to see if there was a possibility that the XP-86 could also go supersonic.
This test was done on October 19, five days after Yeager’s flight, in which
George Welch was tracked at Mach 1.02. The tests were flown again on October
21 with the same results. Since Welch had been performing the very same
flight patterns in tests before October 14, there is the possibility that
he, not Chuck Yeager, might have been first to exceed the speed of sound."

"Jim Wilkins" wrote in message news:unbm6t$kjnl$1@dont-email.me...

"Complete Aerogeek" wrote in message
news:7ba053af-5151-4b6c-a6e9-0e815263ad86n@googlegroups.com...

>If anyone can present authentic copies of NAA test program flight data
>from this date to say otherwise, i would be happy to see it but otherwise,
>it a just another zombie myth.

Here's a possible lead:

https://plane-encyclopedia.com/cold-war/north-american-xp-86/
"North American test crews heard about this feat through rumors and
persuaded NACA to use its equipment to track the XP-86 in a high-speed dive
to see if there was a possibility that the XP-86 could also go supersonic.
This test was done on October 19, five days after Yeager’s flight, in which
George Welch was tracked at Mach 1.02. The tests were flown again on October
21 with the same results. Since Welch had been performing the very same
flight patterns in tests before October 14, there is the possibility that
he, not Chuck Yeager, might have been first to exceed the speed of sound."

---------------------------------

This expands on Welch's story and repeats that NACA measured 1.02 Mach for
the diving XP-86, -after- Yeager's flight, which doesn't confirm or deny
that he did it before.
https://www.aviatorsdatabase.com/wp-content/uploads/2013/07/Pilot-George-S.-Welch-.pdf