"BOB URZ" wrote in message
...


Scott Ferrin wrote:

Assuming B70's were built and upgraded umpteen times by now,
what do you think the results would be with a re-engine of the
six pack with a
modern supercruise engine such as a F119?

Bob

Actually I'd be surprised if the F119 powered one wasn't *slower*.
The J93 was designed for Mach 3 and high altitudes. The F119 is
not.

I realize that airflow and inlet geometry are critical for a high
mach plane, but what would be different in the guts of the engine?
Did the XB-70 burn a non standard fuel like the SR71?

Hey, it's Xmas. Mebbe I can make another mistake.

For a supersonic aircraft, the purpose of the inlet geometry is to
reduce the supersonic airflow at atmospheric pressure to subsonic
airflow at super-atmospheric pressure. ;-)

This means there's more oxygen to burn more fuel, thus getting more
power. It also runs the engine hotter. The faster the supersonic
aircraft goes, the hotter the engine can run.

This raises the following critical question: how long an engine life
do you want? I understand the Mig-31 Foxhound is _capable_ of
astonishingly high speeds, as it has demonstrated on at least one
occasion in the mideast. It generally doesn't, because an immediate
engine overhaul/replacement is then needed.

The F-119 engined F-22 has fixed inlets and is not especially fast.
The engine, therefore, does _not_ have to be made of the *very*
expensive highest-temperature alloys. My question is, how long would
the F-119 last in a mach3 aircraft like the B-70?