Variable Thrust Liquid or Gel Propulsion for Mission Flexibility

XCOR is proposing to study the combination of desensitized nitromethane (CH3NO2) and gaseous oxygen (GOX) as a propellant combination. Nitromethane has a density of 1.14 and the amount of low density oxygen needed for stable combustion is very low. Compared to nitrous oxide and ethane, this combination has higher density, and a greater range of storage temperatures. What is innovative about this approach is the combination of using desensitized nitromethane for better storage and handling properties, along with a new, small and light spark igniter, and just enough gaseous oxygen to permit reliable ignition and stable combustion of the fuel. Nitromethane has long been recognized as a high performance monopropellant, but is too sensitive for real-world tactical handling. If this fuel is desensitized for safety, it no longer works as a monopropellant because the catalysts no longer work. Adding oxygen to desensitized nitromethane and using spark ignition, making it a true bipropellant system, eliminates these problems at the expense of greater system complexity. Since a very small amount of oxygen is needed, the overall system density is reasonably high.