F-86 and sound barrier

By the way, the "damage" was the result of a design fault in the nose gear
extension mechanism, not a result of excessive speed on climbout.

The damage was caused by fast retraction of the nose gear on take-off (because
of the weak cylinder against building airspeed); the solution to that one was
to fit a restrictor in the hydraulic 'up' line. Any other problems were linked
to, but not the cause of, the damage.

The NAA logs are quite detaioled on this.

Duncan

Exceeding M1.0 in either the Sabre or the Dog was no big deal. You
just pointed them straight down from 40+ and didn't fight it if it
wanted to roll around .95(flap rigging, usually).
Question: didn't Edwards get boomed when Welch went supersonic?
Walt BJ

On 23 Sep 2003 07:47:41 -0700, (Walt BJ) wrote:

Exceeding M1.0 in either the Sabre or the Dog was no big deal. You
just pointed them straight down from 40+ and didn't fight it if it
wanted to roll around .95(flap rigging, usually).
Question: didn't Edwards get boomed when Welch went supersonic?
Walt BJ

It certainly did!

Prior to heading back to North American to debrief with the engineers, Welch
telephoned a friend that he had briefed the day before about what to be
listening for. Excitedly, his friend related that they had been nearly blown out
of bed by a terribly loud ba-boom. The time was noted and it corresponded to
George's dive.

Major General Joseph Swing heard the boom and reported it to Stu Symington.
Hundreds of others heard it too. Many wives ran outside looking for the
tell-tale plume of smoke indicating a crash, but there wasn't any smoke to see.

Ask any of the NAA guys (or the Bell crew as well) who were there at the time.
Welch's boom was quite loud, far more so than Yeagers would be (which makes
sense when you consider that Welch was diving towards the base, whereas Yeager
was in level flight at higher altitude).

My regards,

Widewing (C.C. Jordan)
http://www.worldwar2aviation.com
http://www.netaces.org
http://www.hitechcreations.com

"Corey C. Jordan" wrote:

On 23 Sep 2003 07:47:41 -0700, (Walt BJ) wrote:

Exceeding M1.0 in either the Sabre or the Dog was no big deal. You
just pointed them straight down from 40+ and didn't fight it if it
wanted to roll around .95(flap rigging, usually).
Question: didn't Edwards get boomed when Welch went supersonic?
Walt BJ

It certainly did!

Prior to heading back to North American to debrief with the engineers, Welch
telephoned a friend that he had briefed the day before about what to be
listening for. Excitedly, his friend related that they had been nearly blown out
of bed by a terribly loud ba-boom. The time was noted and it corresponded to
George's dive.

Major General Joseph Swing heard the boom and reported it to Stu Symington.
Hundreds of others heard it too. Many wives ran outside looking for the
tell-tale plume of smoke indicating a crash, but there wasn't any smoke to see.

Ask any of the NAA guys (or the Bell crew as well) who were there at the time.
Welch's boom was quite loud, far more so than Yeagers would be (which makes
sense when you consider that Welch was diving towards the base, whereas Yeager
was in level flight at higher altitude).

Correct me if I'm wrong, but didn't the XP-86 still have the 4,000 lb. thrust J35C-3
at that time? Quite a ways down on thrust from the 5,200 lb. J47-13 of the F-86A,
and the top speed of the XP-86 in the only reference I have handy is given as 618
mph @ 14,000 ft. and 575 mph @ 35,000 ft. (M0.875), versus the 677 (presumably lower
down) of the F-86A. The XP-86 is credited in the same source with first exceeding
Mach 1 on 26 April 1948, but it's implied (not explicitly stated) that it did so on
a 3,920 lb. thrust J35-A-5, and that the J47 was first installed in the F-86A. This
seems more than a bit odd, to install an untried engine in the production a/c
without flying it in the prototype first.

I've read pilot's accounts that say that some F-86As would 'hang up' and not quite
make it through the mach if you didn't do the roll in right, which suggests that the
XP-86 with its lower thrust might well have trouble. Of course, if exceeding mach
was mainly a question of drag rather than excess thrust, then it shouldn't have been
a major problem. I've just always wondered.

Guy

On 23 Sep 2003 05:53:00 GMT, (DunxC) wrote:

By the way, the "damage" was the result of a design fault in the nose gear
extension mechanism, not a result of excessive speed on climbout.

The damage was caused by fast retraction of the nose gear on take-off (because
of the weak cylinder against building airspeed); the solution to that one was
to fit a restrictor in the hydraulic 'up' line. Any other problems were linked
to, but not the cause of, the damage.

The NAA logs are quite detaioled on this.

Duncan

According to Roy Ferrin, the actuator was replaced with one having a
larger diameter piston, and the door linkage was adjusted to close a tad sooner.
I can't see how a flow restrictor in the line will compensate for a lack of
force resulting from inadequate pressure area. If you want more push for a given
hydraulic pressure, you need a larger cylinder.

My regards,

Widewing (C.C. Jordan)
http://www.worldwar2aviation.com
http://www.netaces.org
http://www.hitechcreations.com

(Corey C. Jordan) wrote:

On 23 Sep 2003 05:53:00 GMT, (DunxC) wrote:

By the way, the "damage" was the result of a design fault in the nose gear
extension mechanism, not a result of excessive speed on climbout.

The damage was caused by fast retraction of the nose gear on take-off (because
of the weak cylinder against building airspeed); the solution to that one was
to fit a restrictor in the hydraulic 'up' line. Any other problems were linked
to, but not the cause of, the damage.

The NAA logs are quite detaioled on this.

Duncan

According to Roy Ferrin, the actuator was replaced with one having a
larger diameter piston, and the door linkage was adjusted to close a tad sooner.
I can't see how a flow restrictor in the line will compensate for a lack of
force resulting from inadequate pressure area. If you want more push for a given
hydraulic pressure, you need a larger cylinder.

My regards,

Widewing (C.C. Jordan)

They likely had to cause the NG to retract fast originally
because as mentioned the cyl was weak and they needed to get the
gear up before the airspeed had built up too far. That's what I
gather from the writeup above. Problem likely was that, although
the restrictor would reduce the speed of the retraction, it seems
reasonable that it would combat the purpose of the fast
retraction. Seems reasonable to fit a more powerful jack as they
did.
--

-Gord.