Green Application for Space Power Project Manager(s)/Lead(s) fighter jet uses H-70 propellant (30% diluted hydrazine) for providing the plane emergency power if the pilot Joel Robinson/CS10 loses engine power. Since there have been over 4,400 (256) 544–3513 F-16 planes built, there are a number of these planes that have been retired and await destruction at the Davis Sponsoring Program(s) Monthan Air Force Base in Tucson, AZ. Space Technology Mission Directorate The feasibility testing funded by MSFC investment Center Innovation Fund was to utilize a modified version of the USAF’s green Space Launch System Advanced Development propellant to decompose with the F-16 gas generator, a main component within the emergency power unit Project Description (EPU) assembly. MSFC worked closely with engineers/ chemists at the Air Force Research Laboratory (AFRL), Most space vehicle auxiliary power units (APUs) use adding water content to the AF-M315E to lower antici- hydrazine propellant for generating power. Hydrazine pated combustion temperatures. AFRL mixed the pro- is a toxic, hazardous fuel that requires special safety pellant, performed catalyst heating tests, and provided equipment and processes for handling and loading. In 5 gallons of propellant to MSFC for test operations. recent years, there has been development of two green MSFC disassembled the EPU and configured the test propellants (less toxic) that could enable their use in setup shown in figure 1. A series of 64 pulse operations APUs. The Swedish government, in concert with the were performed over the course of 2 days. Swedish Space Corporation, has developed a propel- lant based on ammonium dinitramide (LMP-103S) Anticipated Benefits that was flown on the Prisma spacecraft in 2010. The United States Air Force (USAF) has been developing Demonstration of green propellant with an alternative a propellant based on hydroxylammonium nitrate (AF- catalyst material could lead to cost savings across the M315E) that is scheduled to fly on the Green Propellant F-16 fleet and SLS booster nozzle gimballing. This test- Infusion Mission in the spring of 2016 to demonstrate ing could further be extended to testing the other green apogee and reaction control thrusters. However, no one monopropellant that has matured: LMP-103S. Both else in the Agency is currently pursuing use of green leading green propellants offer not only increase perfor- propellants for application to the APUs. Per the TA-01 mance characteristics compared to hydrazine (density Launch Propulsion Roadmap, the Space Technology and impulse) but also are less hazardous. Safety testing Mission Directorate had identified the need to have reveals that SCAPE (self-contained atmospheric pro- a green propellant APU by 2015. This is our motivation tective ensemble) suits are not required for transport, for continuing activities. loading, and handling of the propellant, which would lower operations costs and allow for serial operations to The plan proposed by NASA Marshall Space Flight occur for aircraft and spacecraft preparation. Center (MSFC) is to utilize existing F-16 and Space Shuttle hardware to provide a low-cost demonstration Potential Applications testbed for green propellant APUs. During preparation Besides the F-16 EPU and the SLS booster APU, the for the TDM12 solicitation, MSFC was able to acquire U-2 spy plane also uses a form of hydrazine for engine a solid rocket booster gas generator and an orbiter APU restart at altitude. Given further interest, there may be residing at White Sands Test Facility that were no lon- the opportunity to investigate that platform as well. ger needed by the Space Launch System (SLS). Since these test assets are limited in number, a Department of Defense equivalent asset was identified. The F-16 134 C I F Figure 1: F-16 gas generator installed at MSFC Component Development Area Test Cell. Notable Accomplishments References MSFC recently completed feasibility testing of an F-16 MSFC 2014 Center Innovation Fund Final Report, EPU gas generator using a variant of the AF-M315E Green Application for Space Power, J. Robinson. (higher water content). MSFC demonstrated that the gas generator can develop 300 psi of pressure. What is unique about this accomplishment is that the propellant mixture was reactive with the hydrazine catalyst mate- rial (Shell 405). With additional testing, there could be a significant cost savings and safety improvement if the F-16 System Program Office decides to implement this propellant across the vast fleet of F-16 users. Like- wise, SLS may consider transitioning from hydrazine- powered APUs to a green propellant alternative. 135