One-Disk Nutating-Engine Performance for Unmanned Aerial Vehicles

Abstract

The nutating engine is a new type of internal combustion engine. The engine has unique advantages over conventional piston engines and gas turbines in small power ranges suitable for unmanned aerial vehicles (UAV), and other applications. This publication is the original presentation of the performance potential of the simplest version of the engine, a one-disk engine operating at constant compression ratio, for light airframe propulsion. In its basic configuration the core of the engine is a nutating nonrotating disk, with the center of its hub mounted in the middle of a Z-shaped shaft. The two ends of the shaft rotate, while the disk “nutates,” performs a wobbling motion without rotating around its axis. The motion of the disk circumference prescribes a portion of a sphere. A portion of the area of the disk is used for intake and compression, a portion is used to seal against a center casing, and the remaining portion is used for expansion and exhaust. The compressed air is admitted to an external accumulator, and then into an external combustion chamber before it is admitted to the power side of the disk. The external combustion chamber enables the engine to use diesel fuel in small engine sizes, giving it unique capabilities for UAV propulsion. The performance of the one-disk engine configuration for flight Mach numbers from 0 to 1 and altitudes from 0 to 20 km is presented and discussed. The performance with equal compression and expansion volume is compared with the higher-efficiency version with expansion volume higher than compression volume. A companion paper examines multidisk alternative engine configurations and load control schemes.