Meusnier is sometimes portrayed as the inventor of the
dirigible, because of an uncompleted project he conceived in 1784, not long after the first
balloon flights of the
Montgolfiers, and presented to the
French Academy of Sciences. This concerned an elliptical balloon (
ballonet) 84 metres long, with a capacity of 1,700 cubic metres, powered by three propellers driven by 80 men. The basket, in the form of a boat, was suspended from the canopy on a system of three ropes.
Jacques Charles and Les Frères Robert After their successful hydrogen balloon flights in 1783, professor
Jacques Charles and the
Robert brothers built an elongated, steerable craft that followed Jean Baptiste Meusnier's proposals. Their design incorporated Meusnier's internal
ballonnet (air cell), a rudder, and a method of propulsion. On 15 July 1784 the brothers flew for 45 minutes from
Saint-Cloud to
Meudon with M. Collin-Hullin and
Louis Philippe II, the Duke of Chartres in their elongated balloon. Rather than 80 men it was fitted with oars for propulsion and direction, but these proved useless. The absence of a gas release valve also meant that the duke had to slash the
envelope to prevent it rupturing when they reached an altitude of about 4,500 metres (15,000 ft). On 19 September 1784 the brothers and M. Collin-Hullin flew for 6 hours 40 minutes, covering from Paris to
Beuvry near
Béthune, passing over
Saint-Just-en-Chaussée and the region of
Clermont de l’Oise. This was the first flight over 100 km. ==Meusnier's military career==