Multi-Objective Propeller Design for mini-UAV

Ohad Gur (Israel Aerospace Industries)

CHALLENGE - The propeller design for a mini-UAV is mainly based on on performance considerations. Two design conditions are considered, which make the design procedure a multi-objective design problem. In the classic propeller design method, the cost function is either the thrust at given shaft power or minimum shaft power at given required thrust.

SOLUTION -  This study presents two cost functions that are loiter fuel-flow at the required flight condition and the thrust at ceiling at given throttle. In this way, the cost function no longer refers to the isolated propeller, but takes into consideration the engine characteristics as part of the optimization procedure. This gives immediate performance estimation as part of the design process, and avoids the requirement to calculate the performance of the vehicle as a retroactive process after the propeller design. Three additional flight conditions are considered, which cover other required performance constraints. These include slow loiter at low altitude, catapult thrust, and climb performance.

BENEFITS - modeFRONTIER has been used to calculate the performance for three different propeller concepts:  an existing wood propeller family, an existing composite propeller family and an optimized (no structural consideration) propeller family.