Rocket propellant and propulsion technology improvements can be used to reduce the development time and operational costs of new space-vehicle programs. Advanced propellant technologies can make the space vehicles safer, more operable, and better performing. Five technology areas are described: monopropellants, alternative hydrocarbons, gelled hydrogen, metalized gelled propellants, and high-energy density materials. The benefits of these propellants for future vehicles are outlined using mission study results and the technologies are briefly discussed.

The tube burner was developed to quantify the regression rate and combustion efficiency of fastburning cryogenic solids. The project objective was to demonstrate that fuels which are gases or liquids at room temperature could be condensed and burned as cryogenic solids in a controlled manner, which would support the idea that high energy density material (HEDM) could be burned as an additive in solid cryogenic fuel, e.g., solid hydrogen. We have now measured regression rates and mixing/combustion efficiencies of ten cryogenic solid hydrocarbon fuels with the tube burner under conditions where hybrid rockets operate, i.e., pressure and mass flux up to 800-psi and 60-g/cm2-s. Ported fuel cylinders with outside diameter of 0.9inch, port diameter of 0.4-inch, and lengths of 3inches and 6-inches have been burned with gaseous oxygen mass flow rates ranging from 5- to 30-grams per second. Regression rates of the cryogenic solid hydrocarbons are between two and eight times faster than conventional hybrid rocket fuels, e.g., Plexiglas and HTPB. Pentane, the most extensively studied fuel, burns four times faster than HTPB. Combustion efficiency is degraded by incomplete mixing of fuel and oxidizer, which was more pronounced in burns of 6-inch fuel cylinders, where O/F ~ 1, than in burns of 3-inch fuel cylinders, where O/F ~ 2. Higher pressure burns improved combustion efficiency of the shorter cylinders more than the longer cylinders. Maximizing specific impulse in propulsion applications requires that hydrocarbons be burned fuel rich to produce the lightweight CO combustion product rather than CO2. This paper reports on burns of 3-inch pentane cylinders at the near optimum O/F ~ 2.5.

Rocket propellant and propulsion technology improvements can be used to reduce the development time and operational costs of new space vehicle programs. Advanced propellant technologies can make the space vehicles safer, more operable, and higher performing. Five technology areas are described: Monopropellants, Alternative Hydrocarbons, Gelled Hydrogen, Metallized Gelled Propellants, and High Energy Density Materials. These propellants' benefits for future vehicles are outlined using mission study results and the technologies are briefly discussed.

A corona excited supersonic expansion (CESE) source (1) has properties that are well suited to the study of transient molecular species with a high resolution Fourier transform spectrometer. This source is run with a continuous dc discharge and a high speed Roots pumping system. The source of transient molecules is relatively confined and quite intense when compared to flowing afterglow or hollow cathode sources. The discharge serves not only to produce the transient molecules, but also to excite the desired molecules into high electronic states, which can be observed by emission in the ultraviolet and visible spectral regions. The supersonic expansion of the source rotationally cools the transients, thereby reducing spectral congestion from overlapping bands and reducing the Doppler line width of the rotational transitions.