HyImpulse Small Launcher SL1 - Access to Space with Hybrid Propulsion

The Small Launcher SL1 is a hybrid propulsion based small satellite launch vehicle that is currently under development at HyImpulse Technologies GmbH, a New-Space startup, and a spin-off out of the German Aerospace Center(DLR). SL1 will be able to place payloads up to 400 kg into a 500 km SSO. Designed specifically for affordability, responsiveness and high launch cadence, SL1’s salient characteristics derive from the usage of hybrid propulsion units in all its three stages. The first and second stages are powered by turbopump-fed 75 kN HyPLOX75 motors (8 and 4 numbers respectively). The third stage is powered by 4 25kN HyPLOX25 motors. The HyPLOX75 motor has already been tested successfully in September 2020 and became the largest hybrid motor ever to be tested in Europe. Powered by paraffin wax (fuel) and liquid oxygen (oxidizer) as propellants, the motor can reach a high specific impulse like traditional KeroLOX liquid systems. Development of a fully carbon-neutral way to produce paraffin wax using the Fischer-Tropsch process is being prepared at HyImpulse and will be explained in the paper. A technology demonstrator in the form of a Sounding Rocket SR75 is being manufactured in parallel with key critical systems undergoing qualification tests. SR75 is slated to be launched in Q3 2021 and will flight validate the HyPLOX75 motor. The current paper will detail the results of the progress and advancements made in the design of SL1 and its key critical systems during the last year. In particular, details about SL1’s design methodology and system architecture will be described. Additionally, progress on HyPLOX75 test firing, cryogenic LOX tank manufacturing, avionics and GSE development will also be described.