--SNIP--
A6906 has the single Lewis and no mention of the original Vickers installation. Knowing that this is a Hooper built aeroplane I wonder who built the other one? The serial number is not in a range mentioned in either Windsock but I think that I need to read both books again to get back up to speed.
Hi Simon, looking forward to this build! What's the other serial you're looking for, again? I've got some references that might help (being a bear of very little brain I get confused pretty easily these days

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RE: the cowling, as I understand it the reinforcements weren't structural in the sense of strengthening the cowling or compensating for cutouts, they were to keep the retaining cables & turnbuckles from falling off. In Mick Davis's Sopwith book he wrote:
The overhung engine mounting offered very little support for the engine cowling and that component was in danger of detaching under vibration, with potentially catastrophic results. A simple Sopwith solution was patented (Patent 127847). The cowling ring that attached to the fuselage longerons was made of V section. The engine cowling had a V-shaped channel around its rear end, that engaged the cowling ring. A cable was then fitted into the recess and tensioned by use of a turnbuckle. This innovation was continued on the Pup, Triplane and Camel, but it was found that engine vibration could loosen the turnbuckle and so retaining clips had to be strapped across, to secure the cowling to the fuselage.Interestingly enough, I was just reading an initial flight test report of a repro Triplane from the early 1990s where that very thing happened, the retaining cable worked loose and took off part of the sheet metal, fortunately the pilot/builder was able to set her down without further incident.
Dutch