[1] During World War I he was granted patents for methods of in-flight disposal of burning fuel, of metal propellers and for bomb releases.
Towards the end of the war he flew with the Belgian Air Force and completed a series of calculations over propeller efficiency.
[citation needed] They built a series of military prototypes, starting with the Dyle et Bacalan DB-10 heavy bomber of 1926.
[5] In 1925, de Monge joined car and motorcycle makers Impéria at Liège as chief research engineer.
[6] This had been almost completed in Paris in 1940 but when France was occupied by Germany it was moved to the French countryside, where it was hidden for the next thirty years.