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THE LIFE AND ADVANCED TECHNOLOGY OF ARMAND DEPERDUSSIN

ARMAND DEPERDUSSIN, pioneer French airplane manufacturer, was larger than life. He had been a traveling salesman, a cabaret singer and a silk tycoon. His aeroplanes were the world’s first to exceed 100 mph and 200 km/h. These aircraft won successive Gordon Bennett air races, 1912 and 1913, and the first Schneider Cup in 1913.

Yet, in the eyes of the French government, Deperdussin was something of a con artist, his notoriety causing SPAD, originally Société de Production des Aéroplanes Deperdussin, to change its name, twice.

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Armand Deperdussin, 1860 – 1924, French aviation entrepreneur.

The Deperdussin Monocoque is the most famous aircraft to carry his name. Built in 1913, this aircraft was technically advanced, not because of Deperdussin’s design expertise, but rather his skill in hiring a talented engineer.

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This replica of the Deperdussin Monocoque resides at the Owls Head Transportation Museum, Owls Head, Maine (http://owlshead.org).

Deperdussin’s Louis Béchereau enhanced themes originated in Swiss engineer Eugene Ruchonnet’s Cigare aircraft, so named because of its monocoque fuselage. Standard practice at the time was to use a box-girder wire-braced construction. In lieu of this, the monocoque fuselage is formed of laminated layers, its surface being a load-bearing element.

Longitudinal fuselage halves were formed of three thin cross-grained layers of tulipwood, total thickness of about 1/8 inch, covered with doped fabric inside and out. Then the two halves were mated with attachments for engine, controls, landing gear and tail structure. In many aspects, the 1913 Deperdussin monocoque had a lot in common with that of the World War II De Havilland Mosquito (http://wp.me/p2ETap-2nU).

The Monocoque was a monoplane; this, in an era of biplane dominance. On the other hand, its retention of wing warping instead of ailerons was an old-fashioned means of lateral control.

Controls

The pilot’s controls consisted of an inverted-U fixture with a steering wheel for wing warping and its fore/aft movement giving the elevators’ pitch control. A foot-bar operated the rudder.

Power came from a 14-cylinder Gnome air-cooled rotary producing 160 hp. This Lambda-Lambda, as it became known, was essentially a pair of 7-cylinder Gnome Lambdas spinning around a single crankshaft. Its propeller’s oversize spinner and engine cowling contributed to the Monocoque’s sleek appearance, as did a streamlined fairing for the pilot’s headrest.

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Streamlining of the 1913 Deperdussin Monocoque was years ahead of its time. Image from Milestones of the Air by John W.R. Taylor and H.F. King, McGraw-Hill, 1969.

The 1913 Monocoque and its 1912 antecedent were extremely successful air racers. Pilot Jules Vedrines and his Deperdussin were timed at 174.10 km/h (108 mph) at the Reims Gordon Bennett races in 1912, the first aeroplane to break 100 mph. Quoted in The Air Racers, he said “The controls are so light that I can maintain my flyer in perfect poise with only the thumb and forefinger of my left hand.”

Perhaps there’s a bit of bravado in this comment, as seen in a video of a modern Deperdussin Monocoque replica at Owls Head Transportation Museum (http://goo.gl/zxHdwf.) Note especially the exercise of control on takeoff and landing. See http://wp.me/p2ETap-1k9 for other Owls Head details.

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Then, as now, air racers waste no power in altitude. This Deperdussin Monocoque rounds a Reims pylon in 1913. Image from The air racers: Aviation’s golden era, 1909-1936 by Terry Gwynn-Jones, foreword by Sir Thomas Sopwith CBE, Pelham Books, 1983.

In 1913, Maurice Prevost and a float-plane version of the Monocoque won the first Schneider Cup, part of which required demonstration of each seaplane to taxi 5 km. At Reims that year, his clipped-wing conventional-gear Monocoque ran 126.67 mph, thus breaking the Euro-magical 200-km/h barrier.

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The barely controlled fury of a Deperdussin Monocoque is evident in this Reims photo, 1913. Image from The Air Racers.

However, Armand Deperdussin’s life fell apart in 1913 too. He was arrested on charges of fraud, allegedly using forged receipts from his silk business as security on loans. Inexplicably, he was jailed until brought to trial in 1917.

Deperdussin’s company went into administration in 1913, and it changed its name to Société Provisoire des Aéroplanes Deperdussin. Investment dried up and a consortium led by Louis Blériot bought up its assets. They kept the SPAD acronym by changing the name again to Société Pour l’Aviation et ses Dérivés.

SPADs designed by Béchereau went on to make aviation infamy (the A2, see http://wp.me/p2ETap-fB) and renown (the XIII, see http://wp.me/p2ETap-1RL).

Through all this, Deperdussin claimed he had used much of the money to promote French aviation (likely true). Nevertheless, he was convicted and sentenced to five more years’ imprisonment. As a concession to his being a first offender (and no doubt reflecting his incarceration since 1913), he was granted an immediate reprieve.

Alas, Deperdussin never recovered from the ordeal. He took his own life in 1924. ds

© Dennis Simanaitis, SimanaitisSays.com, 2014

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