Novel Hypergolic Green Fuels with Hydrogen Peroxide for Propulsion Systems

By combining the advantages of chemicals from two different classes, a series of catalytically promoted green hypergolic fuels named polyamine/alkanolamine-based hypergolics (PAHyp) with highly concentrated hydrogen peroxide (96%) as an oxidizer was developed. In this paper, a novel recipe based on N;N; N⁰N⁰-tetramethylethylenediamine (TMEDA) and N-methyldiethanolamine (MDEA), named PAHyp 1, is characterized. Samples with different volume proportions of TMEDA and MDEA catalyzed with 0.5–4 wt % of copper salts were prepared. It was demonstrated that, by adding low catalyst loadings of 1–2 wt%, ultrafast ignition (as low as 8 ms) can be measured. Fast ignition is important to avoid a hard start in the startup phase, and reduced catalyst loading is important to avoid loss of performance in terms of specific impulse. To evaluate the system’s performance, an orbital transfer maneuver of a geostationary satellite that burns monomethylhydrazine with nitrogen tetroxide was considered. It was demonstrated that when using green formulations based on TMEDA/MDEA, smaller propellant tanks are required (because of the higher density of the green propellants), though more propellant mass is required due to a slightly low specific impulse. Besides good performance and reliable ignition, good storability is crucial for long-term space applications. Remarkably, although TMEDA is sensitive to air, visual inspection, ignition tests, and Fourier-transformed infrared spectroscopy analysis revealed that formulations with volume proportions of at least 60% of MDEA stored in vials filled with air survived with no signs of degradation after 14 months. Finally, to meet the requirement of long-term missions of several years in space, a hypergolic tripropellant feed system was proposed.