Re: Concorde's Engines

Date:         25 Jun 99 01:32:57 
From:         greg@sherrill.kiva.net (Gregory Travis)
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In article <airliners.1999.655@ohare.Chicago.COM>,
Brad Crosier  <bradcrosier@integrityonline32.com> wrote:
>Gregory Travis wrote:
>
>> I've always wondered about that.  How does the >INLET< produce thrust?
>
>My understanding is it's a bit of a misnomer.  The inlet doesn't
>actually produce thrust, but it does act as a compressor (with no moving
>parts, save the "spike," which moves fore and aft).  The spike triggers
>a sonic shockwave, which is reflected down through the inlet.  As
>airflow crosses a shockwave, it's velocity decreases and it's pressure
>increases - the same as when it goes through a compressor stage of the
>turbine engine.

That's my understanding as well.  That sounds like a straightforward
ramjet engine and that's the mode that I believe the SR-71's engines
operate in at speed.

The inlet doesn't produce thrust.  Thrust is produced, as it always is,
by expanding air by heating it (by burning fuel) and directing that
expanded air out rearward.

greg
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