Felix du Temple de la Croix (known almost
universally as "Felix du Temple") patented his design for an
aerial machine in 1857. The design featured retractable
wheeled landing gear, a tractor propeller, an internal
engine and a boat-shaped hull (Mons. Du Temple had been a
French Naval officer). He believed that a 6 h.p. engine
would suffice to lift the machine, which had an estimated
weight of about one ton. To pursue his design, Felix du
Temple constructed numerous bird-shaped models and deduced
that a dihedral angle to the wings would assist in
stability, as well as placing most of the weight to the
front of the machine. He ultimately worked with his brother,
Louis, to build a large-sized version of his design. Finding
existing steam engines to not be lightweight and powerful
enough, in 1867 the two brothers built and patented an
innovative "hot air" steam engine.
Félix Du Temple de la Croix Monoplane of 1874
By 1874 the du Temples had constructed a
large finely-built monoplane, at Brest, France, with a wing
span of some 40 feet and a weight (minus the operator) of
only about 160 pounds. At least one attempt to actually fly
the machine was made and it is generally agreed that after
gaining speed down an incline, the flying machine lifted off
for a short time and then returned to the ground, with both
machine and operator uninjured.