The most prolific and enduring of the Fairey IIIs was the final model, the IIIF, which was designed to meet Air Ministry Specification 19/24 for a three-seat spotter/reconnaissance aircraft for the Fleet Air Arm and a two-seat general purpose aircraft for the Royal Air Force. The IIIF, which first flew on 20 April 1926,[7] had a more streamlined engine installation and initially a fuselage of mixed metal and wooden construction, with similar wings to the IIID, although later production aircraft were fitted with an all-metal fuselages and wings.[8]