Re: [NTLK] up in the sky

From: Mark Bock (
Date: Mon Jun 24 2002 - 09:17:24 EDT

>Um, IANAE but... I don't think the SR-71's jets ever operate as ramjets.

Not true ramjets, no -- that's why I said "quasi-ramjets".

>The huge cones (which are adjustable) serve to keep the air intake speed
>below mach 1. It is true that the compressors don't do much compressiong
>anymore at cruise speed, but they keep churning...

 From, also mentioned
in Ben Rich's book about the Skunk Works (he designed the engine
inlet system):
The SR-71 is a delta-wing aircraft designed and built by Lockheed.
They are powered by two Pratt and Whitney J-58 axial-flow turbojets
with afterburners, each producing 32,500 pounds of thrust. Studies
have shown that less than 20 percent of the total thrust used to fly
at Mach 3 is produced by the basic engine itself. The balance of the
total thrust is produced by the unique design of the engine inlet and
"moveable spike" system at the front of the engine nacelles, and by
the ejector nozzles at the exhaust which burn air compressed in the
engine bypass system.

The air compression and ignition in the engine bypass system is what
I was talking about. This is the same concept as a ramjet.

>Isn't a supersonic ramjet called a 'scramjet'?

Yes -- a supersonic combustion ramjet is called a scramjet (see

But in theory a ramjet operates into the low hypersonic range (mach 6
or so), at which point a scramjet becomes necessary to get you up to
mach 8 or 9.


. . . . .
mark bock

"A youth who can't hit a cathedral at thirty yards with a Gatling gun in three-quarters of an hour, can take up an old empty musket and bag his grandmother every time, at a hundred." --Mark Twain

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