Interesting insight - so XM691 was a Flight Test aircraft...?conistoncollie wrote: ↑Mon Jul 02, 2018 8:38 am A late friend of mine worked at BS in the sixties. He had this to say about XM691
It would be silly to say that I knew XM691 well, but it feels like it. It was used by Bristol Siddeley not only for flight test, but also a chase plane, for observation and for photography. The in-flight photograph of the Valiant, used briefly as Pegasus test bed, was probably taken from it.
In 1964 or thereabouts, in the course of my apprenticeship, I spent two weeks in the Flight Shed, and XM691 was there. It was much used and much liked.
Pegasus of course had its origins in the Orpheus, later powered the Harrier.
According to Stanley Hooker's book, the Pegasus began as an amalgam of an Olympus LP (as the fan) and an Orpheus (as the core or HP).