LAUNCH VEHICLE PERFORMANCE USING METALLIZED PROPELLANTS

Gelled metallized propellants provide options for increasing the performance of future launch vehicle chemical propulsion systems by increasing fuel density or specific impulse I-sp, or both. These increases in density and I-sp can significantly increase the payload, reduce the propulsion system liftoff weight, and allow a liquid rocket booster (LRB) to fit into the same volume as a solid rocket booster. As design examples, metallized propellant propulsion systems are considered as replacements for the solid rocket boosters and liquid sustainer stages on the current launch vehicles: both the Space Transportation System (STS) and the Titan IV. These vehicles are considered as examples to understand the real-world integration issues with future vehicles. Propulsion system mass-scaling equations and rocket engine performance predictions are used to estimate the size reductions of the high-density metallized boosters and some of the issues that must be considered before applying these fuels to future boosters are reviewed. A payload increase of 14-35% was enabled for the STS example using O-2/RP-l/Al and NTO/MMH/Al, respectively, while keeping an LRB within the dimensions of the SRB. No tank volume reduction or payload benefit was enabled with O-2/H-2/Al for the Space Shuttle Main Engine. A 11.2-11.6% payload increase for a Titan IV example was possible with NTO/MMH/Al propellants.