Mignet Pou-du-Ciel - Wikipedia

Main article: Mignet HM.14

In 1933, Mignet successfully flew for the first time in his HM.14, the original flying flea, and publicly demonstrated it. In 1934, he published the plans and building instructions in his book Le Sport de l'Air. In 1935, it was translated into English in Britain and serialised in Practical Mechanics in the USA, prompting hundreds of people around the world to build their own Flying Fleas.[3]

Mignet's original HM.14 prototype aircraft was powered by a 17 hp (13 kW) Aubier-Dunne 500 cc two stroke motorcycle engine. It had a wingspan of 19.5 feet (5.9 m), a length of 11.5 feet (3.5 m) and a gross weight of 450 lb (204 kg).[4] It had a usable speed range of 25–62 mph (40–100 km/h).[1] In the UK in 1935 and 1936, many aerodynamic and engine developments took place, notably by Stephen Appleby, John Carden and L.E. Baynes.[2]

Despite the initial popularity of the design, thanks in no small part to the passionate enthusiasm of Mignet himself, the original HM.14 revealed design flaws that could lead to an unrecoverable and often fatal dive under certain conditions; when the front wing was put in a high attack angle for climbing, the high-speed flow of air deflected by the front wing went to the rear wing upper surface, greatly increasing the rear wing's lift, and putting the nose down, the instinctive reaction of pilot being pulling even more the stick, this worsened the situation, as the way to go out of this 'vicious circle' was reducing the front wing incidence, as to command a nose down descent. Also some homebuilders attempted to simplify construction by modifying components such as the wings tips curving up, resulting in extremely dangerous airplanes and deadly accidents that forced the air authorities to ban building more of them.[5] Studies in the UK and France revealed the problem (the HM.14 was small enough to fit in wind tunnels in both countries usually used for scale models of larger aircraft) and corrections were made to the design. Unfortunately, the wave of bad publicity created by the crashes dogged Mignet for the rest of his life and continues to be associated with the design today despite the fact that the basic Mignet configuration has proven to be safe in hundreds of successful homebuilt aircraft and factory built microlights.[2]