This STTR program will mature high density, high regression rate hybrid rocket motor technology through TRL6 through the design, fabrication, and testing of third and fourth stage nanosatellite motors, while preparing designs and sizing for booster stages. Hybrid Rockets offer substantially lower cost compared to storable and cryogenic bipropellant systems, but currently suffer from poor packaging efficiency. During proof of concept work, the use of a high density, HAN based oxidizer system combined with a high density and high regression rate solid fuel were demonstrated as solutions to packaging efficiency, O/F ratio sensitivity, and regression rate limitations of hybrid motors. The HAN based oxidizer has low freezing temperature and no appreciable vapor pressure, being safe, storable, and eliminating the need for special handling and shipping precautions. The high density oxidizer combined with the high density, high performance fuel, creates a hybrid engine system with the density impulse performance of a solid rocket motor, but the throttleability of a bipropellant system, with the safety approaching an inert system. An electrically enhanced ignition system was demonstrated which improved C*, and enables higher performance to be met with shorter motor grains, with the potential for multiple start capabilities. This Phase II program will continue the development of high density, safe, storable, non-toxic hybrid motors to optimize ISP and motor design, improve injector and igniter performance, and mature third and fourth stage motor maturity through full scale motor burns.
The third and fourth stage motor designs are sized using the nanolaunch2000 PSRM-120 and PSRM-30 third and fourth stage motors as the reference motors. While a slight weight penalty is incurred over the solid stage, the lower costs, easier integration, and throttleability reduce launch costs per lb to orbit. During Phase II, improved propellant formulations and combustion efficiencies and reducing injector pressure drop and refining the pressurization system will eliminate the performance penalty of the baseline system. A storable hybrid is a highly attractive alternative for kick motors, being the size of a solid motor but with throttleability and near infinitly storability without a hazard classification. Storable high density hybrids, due to their improved reliability, and high density-isp, also make compelling candidates for mars sample return and planetary missions, as well as nano- and picosatellite propulsion systems. The complete development of the electrical ignition and combustion augmentation system will enable insertion of these high density, low cost, safe hybrid motors into future NASA missions.
Commercial access to space, particularly in the exploding microsattelite field, is hindered by reliable, low cost access. While SLS and other commercial large launchers offer lower $/lb, access relies on available excess space, and integration requirements are stringent. A safe hybrid propulsion system enables ease of integration for ride-along satellites, as well as greatly reduces the timeline (logistics) and cost of independent small launchers. As costs are reduced, on-demand launch capabilities provide a major, economic option for communications and information services. Once scaled to booster sizes, low cost, safe hybrids can dramatically reduce launch costs and logistics, enabling airplane-like space access (anywhere, anytime) to support an expanding orbital and interplanetary commercial space.