Fairchild AT-21 Gunner

The importance of heavy defensive/offensive armament for its bomber aircraft had not been appreciated by US Army Air Corps planners until early in World War II, when information on combat experience in Europe became available to them. This can be illustrated by the fact that the Boeing B-17B Fortress then carried only five machine-guns on separate mountings. Whilst additional weapons could be added to most aircraft, their crews needed training in the most effective deployment of these weapons.

The USAAC lost little time in ordering two specialised gunnery trainer prototypes from Fairchild. The first (XAT-13) was intended to provide team training for a bomber aircraft's entire crew, and this aircraft was powered by two Pratt & Whitney R-1340-AN1 Wasp 9-cylinder radial engines. The second prototype (XAT-14) was of similar layout and powered by two 388kW Ranger V-770-6 inline engines. It was adapted subsequently as a specialised trainer for bomb-aimers, with its defensive guns removed, under the designation XAT-14A. Testing and evaluation of these aircraft resulted in the procurement of a specialised gunnery trainer underthe designation AT-21 Gunner.

A cantilever mid-wing monoplane of mixed construction, the AT-21 had a deep oval-section fuselage, a tail unit incorporating twin fins and rudders and retractable tricycle landing gear, and was powered by two Ranger V-770 engines.

Accommodation was provided for a crew of five, including pilot, co-pilot/gunnery instructor and three pupils. Of the 175 AT-21 s constructed, 106 were built by Fairchild and, to speed deliveries to the USAAF, 39 were built by Bellanca Aircraft Corporation and 30 by the McDonnell Aircraft Corporation at St Louis. Entering service with newly-established air gunnery schools, the AT-21s remained in service until 1944, when they were displaced by training examples of the operational aircraft in which the air gunners would eventually serve. Many of these surplus aircraft were then converted for use as target tugs.