HyPrSpace targets affordable space access with hybrid ‘Baguette’ launchers

“Until a very few years ago in the space industry, the idea was: ‘If it works, we don’t change anything’,” said Sylvain Bataillard, co-founder and chief strategy officer at HyPrSpace. “Then arrived the idea of New Space.”

This triggered an interest in the possibilities of hybrid rocket propulsion for cheaper launch, he told Professional Engineering in the Space Hub at this year's Paris Air Show. Practically all rocket engines run on either solid or liquid propulsion – “extremely mature technologies developed during the Cold War, or even before, on unlimited funds,” as Bataillard put it. 

The two approaches have their own advantages and drawbacks, he continued. “Solid is cheap and simple to use, but pyrotechnical, and you can’t modulate thrust. At the opposite end, you’ve got liquid propulsion, with which you can modulate thrust – it’s really effective. However, it’s extremely complicated due to turbo pumps, and it’s extremely expensive.”

Historically the preserve of research students, hybrid propulsion offers a potential middle ground, being explored by the Bordeaux company. Liquid oxidiser is stored in a tank and injected into a combustion chamber containing the solid fuel – recycled high-density polyethylene in this case. 

“This technology has the advantages of both,” Bataillard said. “It’s simple, it’s cheap – no turbo pumps – but you can modulate thrust and turn the engine on and off. It’s non-pyrotechnical. So on paper, it’s perfect – but it’s not used currently because it suffers from a technological barrier.”

That barrier limits stable fuel mixing and efficiency as engine size increases. HyPrSpace hopes to break through it with a new architecture, which surrounds a cylindrical oxidiser tank with a very thin toroidal combustion chamber, the walls of which are lined with the solid fuel itself. The liquid fuel is injected into the space between the walls of solid fuel. 

“Whatever the size of the engine… the space between fuel blocks is a variable we can choose,” Bataillard said. “The flame is mechanically forced to be really close to the fuel, which brings enough heat to vaporise the fuel, to create enough propulsive material.” 

The approach should also ensure proper mixing of the liquid and solid fuels, he added, and minimise the amount that is unused. 

The firm has embraced not only the design ethos of New Space, but also its tongue-in-cheek naming conventions. The suborbital Baguette One is planned to launch for the first time next year, followed by the Orbital Baguette One (OB1) microlauncher in 2027. Standing at 17 metres (55ft), the OB1 is designed to launch payloads of up to 250kg (550lb) into low Earth orbit.

HyPrSpace hopes its relatively simple, turbo pump-free design could make space more affordable and enable access for more customers – an alternative to SpaceX dominance.