De Havilland DH.15

Galloway Engineering Company

Industry	Engineering, Aircraft engines
Products	Galloway Atlantic engine

Template:One source Template:Infobox aircraft The de Havilland DH.15 Gazelle served as a platform for testing the Galloway Atlantic engine, being a modified version of the de Havilland DH.9A adapted for flight evaluations during 1919–1920. Only a single unit was constructed.

Development

Known primarily as the DH.15, the Gazelle originated from a standard de Havilland DH.9A airframe, retaining its original weaponry but altered to function as an engine test platform. The powerplant installed was the 500 hp (373 kW) Galloway Atlantic, a water-cooled V-12 engine manufactured by the Galloway Engineering Company. This engine combined two six-cylinder inline Galloway Adriatic units on a shared crankcase, supplanting the DH.9A’s typical 400 hp (300 kW) Liberty 12 engine. Despite this upgrade, the outward appearance remained largely unchanged, as the Atlantic was fitted behind a similarly sized rectangular radiator. Both engines featured upright V-12 configurations with crankshafts positioned near the bottom, and in both cases, the propeller shaft was mounted low on the nose. The exhaust system on the DH.15 differed by having extended pipes running straight back from the upper sides of the engine, terminating at the rear cockpit occupied by the observer.

Although two DH.15 aircraft were ordered, only one was ultimately produced. This sole example conducted numerous test flights powered by the Atlantic engine between 1919 and 1920.