Mmm. I might look into that one. I've never really considered the relationship between the Cirrus and Gypsy. I'm wondering if the Gypsy line was developed as a higher performance successor to the Cirrus line, as the 6 cylinder Gypsy Queen powered aircraft such as the DH86 Dragon Rapide and the DH88 Comet, and of course the Gypsy line powered (relatively) high performance aircraft such as the Tiger Moth and the Chipmunk,whilst the Cirrus continued to power the majority of DH powered GA aircraft of the day...
I'm not an engine man but I've worked on both & knew there was a relationship.* The Cirrus & Gipsy engines were designed by the same man, Frank B Halford. http://100.rolls-royce.com/people/view.jsp?id=118
He originally worked as a freelance engine design consultant to various companies including DH until 1944 when he was put in charge of the new DH Engine Company. He also designed the Napier Sabre & was responsible for the DH range of jet engines. Quite a man.
[quote]You're making me jealous old friend!