In article ,
(The Enlightenment) writes:
(Peter Stickney) wrote in message ...
In article ,
(The Enlightenment) writes:
(frank wight) wrote in message . com...
SNIP

The SR71 is limited in speed by the shock wave from the nose of the
aircraft impinging on the inlet lip of the engines over about Mach
3.5. The dash speed of the aircraft is not limited by either engine
thrust or or short term thermal issues.

Theoreticaly the A12 should be faster becuase of its shorter nose.

Uhm, Bernie -

Frederick actualy. Bernxard is my spanish blue cat. I use his email.

But it's pronounced Raymond Luxury-Yacht.
Bright cat.

If one of the limiting factors in an A-12/SR-71's speed
is shock impingement, (Which it is, a;though IIRC it's shoc
impingement on the leading edges of the wings, not the nacelles), how
is a shorter nose going to give you a higher Mach Number? A longer
nose would allow a steeper included angle. (Y'know, all that Opposite
vs. Adjacent stuff from High School Trig.) Unless, of course, Shock
Waves work backwards in Australia?

You got me there.

The shockwave story re impingingment on the nacels I though I read in
a review of sled driver published in Air International.

Are you sure its wing tips? The solution I think is in a protractor
and a photocopy of and SR71 outline.

Yep. That's how I figured it out. The wingtips would be impinged upon
first, then the chines on the outboard sides of the nacelles, then the
outer nafelle lip. Of course, you'd get some complicated shock
interactions going on in the region of the nacelle, so simple
straightedge and protracter stuff is only approximate.

There's a whole bunch of stuff going on that would limit the max speed
to somewhere between Mach 3.2 - 3.5. The shock impingement stuff, the
air temperature at the compressor face, the ability of the fuel to
carry heat away from critical components pop into mind at a first
stab. Those factors all meet at or about Mach 3.5.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster