On Monday 24 June 2002 15:17, Mark Bock wrote:
> >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 http://www.fas.org/irp/program/collect/sr-71.htm, 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.
>
Wow! I actually remembered some of this stuff more or less correctly! I'm
amazed about me!
So, would it be correct to type the SR-71 engines as a hybrid turbo-ramjet?
> >Isn't a supersonic ramjet called a 'scramjet'?
>
> Yes -- a supersonic combustion ramjet is called a scramjet (see
> http://www.aviation-history.com/engines/ramjet.htm).
>
> 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.
>
-- Karel Jansens."Ceteris censeo Fenestras delendas." (Cato - de Terrore Portarum)
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