De Havilland Gipsy Major

The de Havilland Gipsy Major or Gipsy IIIA is a four-cylinder, air-cooled, inverted inline engine used in a variety of light aircraft produced in the 1930s, including the famous Tiger Moth biplane. Many Gipsy Major engines still power vintage aircraft types.

Engines were produced by de Havilland in the UK and by the Australian arm of the company, de Havilland Australia, the latter modifying the design to use imperial measures rather than the original metric measurements.

Design and development

The engine was a slightly modified Gipsy III, which was effectively a de Havilland Gipsy engine modified to run inverted so that the cylinders pointed downwards below the crankcase. The Major was also bored-out (118 mm from 114 mm) compared to the Gipsy III, increasing displacement from 5 L to 6.1 L.

The inverted configuration allowed the propeller shaft to be kept in a high position without having the cylinders blocking the pilot's forward view over the nose of the aircraft.

One initial disadvantage of the inverted configuration was the high oil consumption (up to four pints per hour) requiring regular refills of the external oil tank; this problem improved over time with the use of modified piston rings. First built in 1932, total production of all Gipsy Major versions was 14,615 units.

Further development

In 1934, when Geoffrey de Havilland needed a more powerful engine for his twin-engined transport aircraft, the four-cylinder Gipsy Major was further developed into the 200 hp six-cylinder Gipsy Six. In 1937 even more power was needed for the new D.H.91 Albatross four-engined transatlantic mailplane, and so two Gipsy Six cylinder banks were combined to form one 525 hp (391 kW) Gipsy Twelve 12-cylinder inverted Vee. In military service, the Gipsy Twelve became known as the Gipsy King and the Gipsy Six the Gipsy Queen.