Re: Concorde's Engines

Date:         05 Jun 99 02:09:33 
From:         greg@sherrill.kiva.net (Gregory Travis)
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In article <airliners.1999.600@ohare.Chicago.COM>,
Steve Lacker  <no@spam.thanks> wrote:

>Well, in the case of the Concorde this is true. However, if you REALLY
>want to go fast (like the SR-71) then afterburners become increasingly
>efficient. I forget the exact numbers, but during a typical SR71 mission
>profile (in the area of Mach 3) the turbine section of the engine is
>only producing about 20% of the effective thrust. The variable-geometry
>inlet and the afterburner section produce the greatest portion of the
>thrust.

I've always wondered about that.  How does the >INLET< produce thrust?

>From what I can see, the engines on the SR-71 consist of a fairly
routine turbojet that's surrounded by a fairly routine ramjet.  At high
speed, much (all?) of the air entering the engine inlet is bypassed around
the turbojet core (by the large diverting pipes arranged radially around
the turbojet casing) and to the afterburner section.  In the latter, the
incoming air is simply mixed with fuel and the resultant is burned,
producing thrust.  No moving parts.

greg
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