text: The arrangement was described by Frederick Libby, an American ace who served as an F.E.2b observer in 1916:
  The Royal Aircraft Factory was primarily a research establishment and other experiments were carried out using F.E.2bs, including the testing of a generator-powered searchlight attached between two .303 inch (7.7 mm) Lewis guns, apparently for night fighting duties.
  The F.E.2c was an experimental night fighter and bomber variant of the F.E.2b, the main change being the switching of the pilot's and observer's positions so that the pilot had the best view for night landings.  Two were built in 1916, with the designation being re-used in 1918 for a similar night bomber version of the F.E.2b, which was used by 100 Squadron. In the end, the observer-first layout was retained for the standard aircraft.
  The final production model was the F.E.2d (386 built) which was powered by a Rolls-Royce Eagle engine with 250 hp (186 kW). While the more powerful engine made little difference in maximum speed, especially at low altitude, it did improve altitude performance, with an extra 10 mph at 5,000 ft. The Rolls-Royce engine also improved payload, so that in addition to the two observer's guns, an additional one or two Lewis guns could be mounted to fire forward, operated by the pilot.