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Limiting factors in air and space propulsion systems affect both design and operation of the engines and the energy derived from a fuel source. Translation of the fuel source to energy (combustion) always requires an oxidizer. The process of breaking the energy-laden bonds of the fuel has classically been achieved using the oxygen in air for air-breathing engines or an onboard source of oxidizer for spaceflight. This is a critical limitation for a possible single-stage vehicle, because the weight of the fuel and oxidizer needed to achieve the necessary speed and altitude for orbit is excessive. This problem was overcome using multi-stage engines that are discarded sequentially during vertical ascent. However, the relative inefficiency of fuels currently available perpetuates the requirement for multi-stage engines to achieve orbit. Multi-stage rockets still require onboard fuel and oxidizer at lift-off that can account for over 95% of the lift-off weight.

Spacecraft designs incorporating a propulsion system powered by a more efficient fuel would greatly reduce the oxidizer to payload ratio. This could be accomplished with a single-stage vehicle that uses air while in the atmosphere and switches to onboard oxidizer only after reaching the upper limit of the atmosphere. In this presentation, a revolutionary new vehicle is proposed that incorporates silane-based fuels into an air-breathing spacecraft design that achieves orbit via low ascent angles, where it then switches to onboard oxidizer. A ceramic and alloy propulsion system takes advantage of the properties of silane, utilizing both the oxygen and the 80% nitrogen of the atmosphere for combustion.