by: Stephen T. Lawson [ ]
Originally published on:
HistoryThe 150hp Bentley BR.1 rotary was a British aircraft engine designed by W.O. Bentley. It was built as an alternate motor for the Sopwith Camel constructed under Admiralty contracts for the RNAS. When the RNAS and the RFC combined into the new RAF the RNAS Sqns were renumbered in the 200 series. Such as the RNAS (N) 9 became the RAF 209 Sqn. Thusly the BR.1 was still to be seen almost exclusively in these units.
To overcome the problems faced with the British built Clerget rotary W.O.Bentley came up with idea of an engine - fitted with aluminium cylinders with cast iron liners, and aluminium pistons. Dual ignition was introduced to improve reliability, and the stroke increased to 6.7 inches (17 cm) which allowed power to be increased to 150 horsepower (110 kW). The cost of the engine was also reduced, falling to £605 per engine
The resulting engine, initially known as the A.R.1 for "Admiralty Rotary", but later called the BR.1 ("Bentley Rotary") was manufactured in quantity, although initially against Admiralty orders. It was standardised for the Camel in RNAS squadrons, but unfortunately there were never enough to entirely replace the inferior and more expensive British built Clerget engine, and most RFC Camel squadrons continued to use Clerget engines; in fact licenced production of the Clerget continued. In Nov. 1917 the BR.2, a heavier, more powerful engine (230hp) was first used in a Sopwith Snipe prototype. The BR.2 powered, among other types or aircraftas well. See list below. Coming as it did near the end of the war, the BR.2 was built in smaller numbers than the earlier BR.1 its main use being by the RAF in the early 1920s.
ApplicationsHere is a list of some applications for both the BR.1 & BR.2:
Armstrong Whitworth Armadillo
Bobolink Gloster Grouse
Gloster Nightjar Gloster
Sparrowhawk Grain Griffin
Handley Page Type S
Port Vitoria P.V. 9
The buildIn this scale and under an engine cowling this kit can easily pass for a BR.1 or BR.2. I have to be honest here I am not thrilled about the push rods being molded with the cylinders. I am working with the Copper State Models Bentley rotary kit today. The directions show that originally the push rods were not cast in resin. The problem with casting them in the resin block is that 3 of the 9 cylinders in my review sample have the resin flash connecting the cylinders and push rods. Cleaning it up tends to leave 2 tracks that have to be cleaned up. These will be easy to fix or any minor scars left will be hidden under the shadow of the final placement of push rods. I will use small diameter brass rod at about 7/32 long.
Methods of payment are listed on http://www.copperstatemodels.com/ At this time you must contact them there for prices and delivery schedules.
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