Les Frères Robert

Nicolas-Louis Robert
The world's first manned hydrogen balloon flight. 1783
Born	1760 Paris
Died	1820
Other names	Marie-Noël Robert Robert le Jeune cadet the younger
Occupation	Mechanical engineer, Balloonist
Known for	Builder of first hydrogen balloon Builder of first manned hydrogen balloon Co-pilot of first manned hydrogen balloon flight in 1783 Co-pilot of first balloon flight over 100km 1784

Les Frères Robert were two French brothers. Anne-Jean Robert (1758–1820) and Nicolas-Louis Robert (1760–1820) were the engineers who built the world's first hydrogen balloon for professor Jacques Charles; which flew from central Paris on August 27, 1783. They went on to build the world's first manned hydrogen balloon, and on 1 December 1783 Nicolas-Louis accompanied Jacques Charles on a 2-hour, 5-minute flight. Their barometer and thermometer made it the first balloon flight to provide meteorological measurements of the atmosphere above the Earth's surface.

The brothers subsequently experimented with an elongated elliptical shape for the hydrogen envelope in a balloon they attempted to power and steer by means of oars and umbrellas. In September 1784 the brothers flew 186 km from Paris to Beuvry, the world's first flight of more than 100 km.

The Robert brothers were skilled engineers with a workshop at the Place des Victoires in Paris, who worked with professor Jacques Charles to build the first usable hydrogen balloon in 1783. Charles conceived the idea that hydrogen would be a suitable lifting agent for balloons because, as a chemist, he had studied the work of his contemporaries Henry Cavendish, Joseph Black and Tiberius Cavallo.

Jacques Charles designed the hydrogen balloon and the Robert brothers invented the methodology for constructing the lightweight, airtight gas bag. They dissolved rubber in a solution of turpentine and varnished the sheets of silk that were stitched together to make the main envelope. They used alternate strips of red and white silk, but the discolouration of the varnishing/rubberising process left a red and yellow result.

Jacques Charles and the Robert brothers launched their balloon, the world's first hydrogen-filled balloon, on August 27, 1783, from the Champ-de-Mars (now the site of the Eiffel Tower); Benjamin Franklin was among the crowd of onlookers. The balloon was comparatively small, a 35 cubic-metre sphere of rubberised silk, and only capable of lifting about 9 kg. It was filled with hydrogen that had been made by pouring nearly a quarter of a tonne of sulphuric acid onto half a tonne of scrap iron. The hydrogen gas was fed into the envelope through lead pipes; but as it was not passed through cold water, great difficulty was experienced in filling the balloon completely (the gas was hot when produced, but as it cooled in the balloon, it contracted). Daily progress bulletins were issued on the inflation; and the crowd was so great that on the 26th the balloon was moved secretly by night to the Champ-de-Mars, a distance of 4 kilometres.