Originally Posted by OutOfRunWay
The Concorde's engines produced around 75% of their thrust at M2.2 in the diffusor section and only around 8% came from the actual engine. Another 29% thrust came from the nozzles, whereas the supersonic shocks at the intakes produced around 12% drag.
I've seen other figures quoted also, but same principle. BTW that was at Mach 2.0, i.e., in normal service. At Mach 2.23 (max ever) it would have been different again.
On another forum we wondered about the 12% drag figure. The 75/8/29 % figures would have been derived from the pressure ratios x areas, and therefore would already have taken internal drag into acount. We reckoned the 12% was the external drag of the nacelle structure.
uniuniunium,
One of my SR-71 books quotes even more extreme figures, and also states that under certain flight conditions (throttling back at Mach 3, IIRC) the engine produced no thrust as such at all, and actually moved back on the engine mountings....
Thanks to the contributors !
There IS a difference between having gotten your own head satisfactorily around the various notions and being able to describe them clearly and concisely to somebody else.