The Aerodrome Forum - View Single Post - "Gross" and "Net" rotaries power outputs.

Greybeard · 3 January 2008, 05:19 AM

Thanks Bletchley, as always you've a lot of info and can provide detailed explanations.

BTW, did you see this about Clerget rotaries?
http://www.hydroretro.net/etudegh/mo...erget130ch.pdf

The point that confuses me is indeed with or without windage?

Sources of that time use loosely rotaries' horsepower without specifying if "gross" or "net", not to mention absolute negligence about british and metric units. But windage can't be neglected; the case of Camel is significant: if its british Clerget 9B really developed 126 HP "gross" it couldn't reach same speed of its Naval counterpart and vice-versa... or I must believe that donkeys can fly!

9BF had also a longer stroke (172 against 160) and an higher compression ratio (5.14 vs. 4). Actually, it was credited with 148 BHP on same Data Board document. Nevertheless, Camel powered with it wasn't the fastest, being so for Le Rhone powered one, developing "only" 137 BHP (perhaps "net"). Do you see what I mean?

GB

3 January 2008, 05:19 AM	#3 (permalink)
Greybeard Forum Ace Join Date: Jul 2005 Location: Italy Posts: 698	Thanks Bletchley, as always you've a lot of info and can provide detailed explanations. BTW, did you see this about Clerget rotaries? http://www.hydroretro.net/etudegh/mo...erget130ch.pdf The point that confuses me is indeed with or without windage? Sources of that time use loosely rotaries' horsepower without specifying if "gross" or "net", not to mention absolute negligence about british and metric units. But windage can't be neglected; the case of Camel is significant: if its british Clerget 9B really developed 126 HP "gross" it couldn't reach same speed of its Naval counterpart and vice-versa... or I must believe that donkeys can fly! 9BF had also a longer stroke (172 against 160) and an higher compression ratio (5.14 vs. 4). Actually, it was credited with 148 BHP on same Data Board document. Nevertheless, Camel powered with it wasn't the fastest, being so for Le Rhone powered one, developing "only" 137 BHP (perhaps "net"). Do you see what I mean? GB __________________ ------------------------------------------------------ It doesn't matter what we do but in what relationship we put each other while doing what we do.