Small hybrid rocket engines of a proposed type would burn specially shaped hollow cylinders of solid fuel containing slanted oxygen-injection channels, as shown in the figure. These engines would exploit a vortex flow phenomenon associated with the radial inflow of the oxygen in the channels. The fuel/flow-channeler cylinders could be supplied in or as cartridges that could fit into reusable receptacles.

In a PMMA Vortex Engine, oxygen is injected through holes in the PMMA fuel cylinder

The basic vortex-combustion engine concept, using poly(methyl methacrylate) (PMMA) as the solid fuel, has been investigated previously. The novel aspect of the present proposal pertains to the size range and the means of fabrication. The proposed engines would be too small for conventional machining, making it necessary to fabricate the engines (including the fuel/flow-channeler cylinders) by use of x-ray lithography.

Small engines of the proposed type could be used in their own right as thrusters for small spacecraft or as experimental small-scale prototypes of larger thrusters. After further research to gain better understanding of the vortex flow in question, it might become feasible to apply the vortex-combustion engine concept to develop improved combustion chambers in fossil-fuel power stations, boilers, retorts, gas-fired home furnaces, and turbojet engines.

This work was done by Victor White of Caltech for NASA's Jet Propulsion Labo-ratory. NPO-20594