Disclaimer: This text reflects only the opinion of its author and does not in any way commit the official word of the French Air and Space Academy.
By Michel VEDRENNE, Former Director at Dassault Aviation’s Direction Générale Technique and fellow of AAE
Diamant launchers, developed by France in the 1960s and 1970s, were the first French – and European – space launchers capable of placing satellites into orbit. The year 2025 thus marks the 60ᵉ anniversary of the launch of Asterix, the first French satellite put into orbit, a founding event in the nation’s space adventure. It also corresponds to the 50ᵉ anniversary of the three flights of the Diamant B-P4 launcher, the ultimate evolution of this pioneering family.
The current period is characterized by the development of a dozen “national” launchers in Europe. While these young teams benefit from the technological heritage accumulated over more than sixty years in the field of launchers, they still have to face up to fundamental physical phenomena, sometimes insufficiently anticipated.
The following text describes the difficulties encountered by French engineers at the time, and how they overcame the constraints associated with the Pogo effect – so named by the Americans, who themselves faced this problem a few years earlier with their own launchers. Perhaps this account will shed some light on current projects.
During flight, liquid-propulsion launchers are subjected to a variety of vibratory phenomena, the most restrictive of which is the Pogo effect. Because of their liquid-propulsion first stage, the launchers in the Diamant family have not escaped this difficulty, illustrating from the outset the complexity inherent in the conquest of space.