Re: Concorde's Engines

Date:         24 May 99 01:52:44 
From:         ehahn@mitre.org (Edward Hahn)
Organization: The MITRE Corporation
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In article <airliners.1999.498@ohare.Chicago.COM>, "Bill Herman" <hermanwc@fuse.net> wrote:
>I don't regularly read this group, so sorry if this has been asked
>previously...
>
>Do the Concorde's Olympus engines use some form of afterburner while flying
>supersonic?  A friend of mine doesn't think so, but I don't see how that
>plane can fly at Mach 2 without reheat.  I thought the F-22 was considered
>to be a great technological achievement because of its ability to fly beyond
>Mach 1 at military power (no afterburner).  It's hard to believe that a
>plane designed 20+ years prior to the F-22 already had that capability.

The Concorde does in fact cruise without afterburner.

It turns out that the components of drag for a supersonic aircraft are
at a local maximum at the speed of sound (makes sense - initial
generation of the shock wave would require lots of power).  However,
once past Mach 1, the wave drag is dramatically reduced.

What this means is that both the F-22 and Concorde need an afterburner
to get through Mach 1, but do not require afterburners to maintain a
supersonic speed.

As for the Concorde, remember, it's a pretty light plane, only carries
100 pax, carries lots of fuel in its delta wings, and has four engines
to move it.  The F-22, of course, only has two engines.  Despite this,
the Concorde can barely make it across the Atlantic, and sometimes has
to stop in Boston on the westbound leg to refuel if headwinds or even
minor delays occur.

ed

----
Ed Hahn / ehahn@mitre.org / +1 703 883-5988
The above statement is solely an opinion of the author, and
does not express a position or implied warranty by the MITRE
Corporation.  Really.