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Royal Aircraft Factory S.E.1

The S.E.1 was an experimental aircraft built at the Army Balloon Factory at Farnborough (later the Royal Aircraft Factory) in 1911.

Its place in aviation history is mainly that it was the first in the series of Royal Aircraft Factory designs, several of which played an important role in World War I.

In 1910 the Army Balloon Factory was not actually authorised to design or build aircraft, only to repair them.

When the remains of a crashed Blériot XII monoplane belonging to the army were sent from Larkhill to Farnborough for repair, authorization for a complete reconstruction was sought, and granted.

The result was a completely new design.

A tractor monoplane became a pusher biplane with large balanced fore-elevators, similar in basic layout to the Wright Flyer, but with a fully covered fuselage.

Ailerons were fitted to the top wing, and twin balanced rudders were mounted behind the propeller, but out of its immediate slipstream.

The only obvious component of the Blériot that found its way into the new design was its 60 hp (45 kW) E.N.V. Type F engine.

The S.E.1 made its first flight, a straight mile in the hands of its designer Geoffrey de Havilland on 11 June 1911.

Further flight testing revealed control problems and the area of the front wing/elevator was adjusted to try to bring together the centre of pressure and the hinge line and make the S.E.1 stable in pitch.

By the beginning of August the front surface was fixed and carried a conventional trailing edge elevator.

An attempt to improve the turning characteristics was made by stripping the side covering of the nacelle to reduce side area.

De Havilland continued to fly the S.E.1 until 16 August.

On 18 August the aircraft was flown by the inexperienced pilot Lt Theodore J. Ridge who was the assistant superintendent at the factory.

Both de Havilland and a factory engineer warned him against flying it.

The combination of the inexperienced pilot and the marginally controllable aircraft proved fatal, while landing with the engine off, he made a sharp turn, the S.E.1 stalled and spun in, killing Lt Ridge.

No attempt to rebuild the S.E.1 was made, and the design was abandoned.





29 ft 0 in (8.84 m)


38 ft 0 in (11.58 m)


11 ft 6 in (3.51 m)

Wing area

400 sq ft (37 m2)

Empty weight

1,200 lb (544 kg)

Gross weight

1,640 lb (744 kg)


1 × E.N.V. Type F, V-8 water-cooled piston engine,

60 hp (45 kW)


2 bladed fixed pitch pusher propeller

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