Interesting Article Flyer43. Until Louis Breguet made his return, Marquis Raul Pateras Pescara certainly made the most convincing advances.
Dave, i think the Leishman calcs for helicopter performance stand, but i question the quoted 24 SHP of that V8 Antoinette engine. This site gives 50 SHP for a later version of the V8:
http://www.hydroretro.net/etudegh/antoinette.pdf
Wikipedia is not so useful here:
http://en.wikipedia.org/wiki/V8#History
This site talks about the 24CV Antoinette engine.
http://www.eurocopter.com/bourget/in...news.php?id=20
The problem here is that in france there used to be some strange system for "CV" that has an indirect relation to SHP:
http://fr.wikipedia.org/wiki/Cheval-vapeur