kW) Wolseley Viper and the 230 hp (170 kW) Siddeley Puma. Trials of the Puma engine were carried out in February 1918; it was found to confer marginally better performance than the Hispano-Suiza and Arab engines but was difficult to install and unreliable. In September 1918, trials of a high-compression model of the Puma were carried out but it was found to have no significant performance benefit and this avenue was not pursued. The Type 22 was a proposed version adapted for a radial or rotary engine, either a 200 hp (150 kW) Salmson radial, a 300 hp (220 kW) ABC Dragonfly radial (Type 22A) or a 230 hp (170 kW) Bentley B.R.2 rotary (Type 22B). The type number was eventually used for the Bristol F.2C Badger, a completely new design. The All-Metal Bristol Fighter The Bristol M.R.1 is often described as an all-metal version of the F.2b but was a new design, although its fuselage was positioned between the upper and lower wing as with the F.2b. Two prototypes were built; the first flew on 23 October 1917, but the M.R.1 never entered mass production. American versions When the US entered the war, the Aviation Section, U.S. Signal Corps of the United States Army lacked any competitive combat aircraft either in inventory or under construction. On 1 August 1917, General John Pershing, the commander of the American Expeditionary Forces on the Western Front, issued his personal recommendation for the Bristol Fighter to be built in the United States, leading to plans for the development and production of an American version of the Fighter by the United States Army Engineering Division. Original proposals for American production had the Hispano-Suiza engine. On 5 September 1917, a F.2B Fighter was delivered to the Smithsonian Institution, Washington, United States. Attempts to begin production in the United States floundered due to the decision by Colonel V. E. Clark of the Bolling Commission to redesign the Fighter to be powered by the Liberty L-12 engine. The Liberty was unsuitable for the Bristol, as it was far too heavy, bulky and the aircraft had a nose-heavy attitude during flight. A contract for 1,000 aircraft was placed initially with the Fisher Body Corporation then cancelled and reallocated to the Curtiss Aeroplane and Motor Company. On 7 December 1917, the order was doubled to 2,000 aircraft. On 25 January 1918, the first aircraft, which was given the name