Lard Used as a Fuel for Hybrid Rocket Motors

A bio-derived fuel, lard, was successfully tested using a laboratory scale hybrid rocket motor and a static test stand at the University of Tennessee-Knoxville. The experimental setup used gaseous oxygen as the oxidizer. Twenty-three experimental tests were successfully conducted with lard and oxygen. The nine-inch fuel grains used in the current investigation produced a measured thrust ranging from 70-145 Newtons (15-33 pounds) with calculated specific impulses ranging from 122-181 seconds. All the tests conducted were intensely fuel rich, and had equivalence ratios ranging from 0.2 to 0.45. The low equivalence ratios are partially due to unburned fuel particles that exit the nozzle. The tests conducted have shown that the regression rate of the lard was higher than that of other fuels, such as HTPB (hydroxyl-terminated polybutadiene), used in hybrid rocket motors. Lard has produced results similar to those obtained by researchers at Stanford University using paraffin. This investigation has provided sufficient evidence to indicate that lard merits further study as a fuel for hybrid rocket motors.