Deperdussin Monocoque

Deperdussin Monocoque
The Deperdussin Monocoque racer and four of its pilots. From left to right: Guillaume Busson, René Vidart, Jules Védrines and Maurice Prevost
Role	Racer
Manufacturer	SPAD
Designer	Louis Béchereau
First flight	1912

The Deperdussin Monocoque was an early racing aircraft built in 1912 by the Société Pour les Appareils Deperdussin, commonly abbreviated "SPAD". It is so named because of the method of construction of its fuselage. The aircraft is noted for winning the Gordon Bennett Trophy in 1913, and for raising the world speed record for aircraft to 126 mph (203 km/h). This aircraft is sometimes confused with the Deperdussin 1912 racing monoplane, which won the 1912 Gordon Bennett race at 106 mph (171 km/h) and was first aircraft to fly faster than 100 mph (160 km/h).

Background

The first use of monocoque construction in aviation is attributed to Eugene Ruchonnet, a Swiss marine engineer who had built an aircraft nicknamed the Cigare in 1911, which had a fuselage constucted by building up several layers of thin wood, each lamination being applied at right angle to the one underneath. The usual method of construction of an aircraft's fuselage at this time was to use a wire braced box-girder covered in fabric. Ruchonnet's technique, in which the outer surface of the structure is load-bearing, would become the usual method of aircraft construction.

The Deperdussin Monocoque was a development of an earlier racing aircraft designed by Louis Bechereau which was first flown at the end of 1911 and which won the 1912 Gordon Bennett Trophy race. This aircraft made partial use of the monocoque technique, with a pair of curved load-bearing shells used in conjunction with a conventional wooden box-girder.

Design

The Deperdussin Monocoque was a mid-wing monoplane with parallel-chord wings with the spars made of hickory and ash and ribs made of pine. The fuselage was made in two halves, each made by glueing and pinned a layer of tulip wood to a framework of hickory supported by a former, and then applying two further layers of tulipwood, the thickness of the shell being around 4 mm (⁵⁄₃₂ in). The shells were then removed from the formers, internal fittings added and the two halves glued together and covered in fabric. Every effort was made to reduce drag: a large spinner was fitted over the hub of the propeller and the undercarriage was an aerodynamically clean design made from a pair of u-shaped plywood frames.

Service History

Deperdussin entered three aircraft for the 1913 Gordon Bennett Trophy race, which was held as part of the week-long aviation meeting at Rheims in September 1913. These were flown by Prevost, Gilbert and Rost. A fourth aircraft was entered by Crombee, representing Belgium in the competition. The aircraft flown by Prevost had been modifiedby rcucing the span of the wings. Elimination trials to decide who would be the three entrants to form the French team. Prevost came first and Gilbert third, second place being won by Jules Vèdrines in a Ponnier monoplane.

The race was won by Prevost, who completed the 200 km (120 mi) course in 59 min 45.6 seconds, an average speed of 200.5 km/h (124.6 mph)

Specifications (1913 Gordon Bennett winner)

Data from

General characteristics

• Crew: 1
• Length: 6.1 m (20 ft)
• Wingspan: 6.65 m (21 ft 10 in)
• Wing area: 9.7 m² (104 sq ft)
• Gross weight: 612 kg (1,350 lb)
• Powerplant: 1 × Gnome Lambda Lambda air cooled 14-cylinder two-row rotary, 120 kW (160 hp)
• Propellers: 2-bladed Chauvière, 2.31 m (7 ft 7 in) diameter

Performance

• Maximum speed: 210 km/h; 110 kn (130 mph)

References

• Wayne Biddle - Barons of the Sky: From Early Flight to Strategic Warfare. Johns Hopkins University Press, 2001. ISBN 0801868289.
• Émile Auguste Duchêne - Flight Without Formulae: Simple Discussions on the Mechanics of the Aeroplane. Longmans, Green and co., 1914.
• Jane's All the World's Aircraft. London: Sampson Low Marston. 1913. pp. 89.