To satisfy NASA requirements for a Mars Ascent Vehicle (MAV), C3 Propulsion has designed, built, and tested a Constant Volume (CV) combustion engine. This rocket engine is novel in that it applies a thermodynamic cycle unusual in rocketry applications.

This CV engine can play a critical role in current NASA In-Space Propulsion Program. It was specifically designed for use with non-toxic, low temperature propellants. Its versatile multi-use capabilities for integrated main propulsion and reaction control, make it applicable for a broad range of missions. Other NASA applications would include lunar/planetary ascent/descent, integrated main propulsion and reaction control for orbital insertion/maneuvering, and return to Earth.Non-NASA applications include the potential for use on military platforms such as Kinetic Kill Vehicles (KKVs), as well as adaptation for commercial satellites using hypergolic propellants for orbital maneuvering and station keeping. Furthermore, C3 Propulsion will continue to leverage existing experience and expertise from its pool of technology partners at Aerojet, AMPAC-ISP, Lockheed-Martin, and their respective R&D efforts. Moreover, to increase its technology transition potential, C3 Propulsion works with business specialized in SBIR technology transition, like Vital Strategies, LLC. This ensures the alignment of small business inventiveness with industry technology gaps, as corporations make cost-effective responses to key national needs, as well as consumer needs.

What is the need for a CV engine?

Extensive trade studies on Mars Ascent Propulsion have been conducted. The results of a 2001 study indicated that a conventional two-stage solid would be the most promising and lowest risk for a Mars Sample Return mission. A subsequent study examined the trade between pressure fed vs. pump fed engines and reached the same conclusions obtained in previous studies. As long as conventional Constant Pressure (CP) engines cycles continue to be at the core of propulsion system trade studies, the result of any new study will not stray far from results obtained in the past. For non-traditional propellant systems to be competitive, there needs to be a fundamental change in the engine cycle as well, otherwise the optimum has already been identified.

The Innovation

Not only the CV engine has nearly identical specific impulse as the CP engine with the same mass flow and throat area, but also the nozzle optimizes at the same area ratio. Advantages of the CV combustion cycle over conventional liquid bi-propellant CP combustion cycles include the elimination of pumps and improved Isp for a given system supply pressure. This engine is not a pulse detonation engine, but an Adiabatic Isochoric Complete Combustion (AICC) engine. The advantages are the simplification of the ignition system, buffer gas injection, and a reduction in the extremely high pressures associated with PDEs.

Specific advantages of the CV propulsion device for the MAV mission include:

  • Light weight, low pressure fuel tanks
  • High chamber pressure
  • Meets martian temperature requirements without any form of active heating or stirring.