"Gross" and "Net" rotaries power outputs.

[Bletchley]

Thank you GB

"I don't think, though, they really fitted 110 hp Le Rhone during winter 1917-18 since, although being about 66 lbs lighter than Clerget, it couldn't give better climb having 20 hp less... I believe they were indeed Le Rhone 9Jby, giving 140 hp, still called "110 hp" like they did with all Le Rhone 9J.

If so (please correct me if I'm wrong), the "big picture" about Camel's engines on the front should be: 130 hp Clerget9B until dec. '17, 110(140?) hp Le Rhone until april 1918, then 140 hp Clerget 9Bf for RAF ex-RFC and 150 hp Bentley BR1 for RAF ex-RNAS?"

That sounds reasonable to me - it would indeed be an odd (retrograde) step to change out the reasonably reliable French built Clerget 9B for a lower powered engine. I would guess that at any one time there would be a mix of different engines on strength in any one squadron, as the new engines were phased in and older ones were lost or returned to the depot, although Fill's data on aircraft turnover in another thread would indicate that this process of 'phasing in' new equipment would be rapid, even in quieter periods, by 1918. I would guess that the more powerful Le Rhone and Clerget engines would have been 'standard' by May or June of 1918.

I would be happier if I could find a reference to a primary source for all this, so I will keep on digging. If true, I am sure someone will have researched this already and written it all down in one of the many Sopwith Camels books that are out there - just a question of finding the right book

Bletchley

[Bletchley]

I have done a bit more digging, and I have started a new thread (Sopwith Camel F.1 Engines) with the information that I have found, as I feel it has now moved away somewhat from the original subject of the thread

Bletchley