By Arie Egozi
A new revolutionary electric motor may give greater range to different types of UAV’s. Currently negotiations continue in an effort to test the motor on an existing Israeli made UAV. The electric engine was developed by American company Polarix and is creating great interest among Israeli UAV manufacturers.
Polarix, in cooperation with a fan jet engine company are developing a battery powered all electric VTOL UAV with enhanced range and endurance by modifying a high L/D ratio UAV airframe. This new electric VTOL UAV is aimed at providing military organizations with a unique surveillance platform that will be quieter and easier to launch/recover than current UAV in use by military forces.
The key disruptive technical component is the development and integration of a new class of electric motor called “Arrayed Controlled Turnless Structures (ACTS) and its integration into the rim of a propulsion fan.
This propulsor integration into this high L/D air frame will provide it with the required VTOL thrust with minimal reduction in its aerodynamic efficiency. It can also be highly useful for other missions where high specific power propulsors can be coupled with light weight and low noise
An integrated fan and the Polarix ACTS motor will provide the full vertical takeoff thrust using high disk loading. The small fan area will retain the high lift to drag ratio of the UAV airframe to provide longer range and endurance not presently available in all electric VTOL .The energy source will be a Li-ion battery system.
The concept is based on the ground breaking development by Polarix of a new type of propulsion motor. It was originally developed under a US Department of Defense program for flight control actuators. It’s very high specific power combined with enhanced efficiency and reliability make it particularly suitable for a rim driving fan application for aircraft propulsion. A propulsion motor version was developed over the last few years by Polarix with private funds.
Presently, all-electric VTOL crafts are substantially diminished in range and endurance due to their very large cumulative fan area requirement which reduces the crafts’ aerodynamics and thus their lift to drag (L/D) ratio. The later reduces both range and endurance. In contrast, Polarix, takes advantage of the much higher specific power and thus total power available from the ACTS motor and power supply to heavily load a much smaller fan to produce the full VTOL thrust, concurrently serving as the cruising propulsion fan but now at much reduced power.
Long range UAV’s are either catapult launched or use a runway and wheels, and use piston engine and fuel tank. Its replacement by the electrical rim driven fan and batteries will allow meaningful structural weight savings which Polarix estimates will reduce the dry weight from 37% to 33% of the craft.
Over the last few years, Polarix has developed and patented this enhanced specific power motor technology and recently designed a rim driven fan configuration with a fan jet engine company.
– The author is an Israel-based freelance writer. He has served in Israel Defense Forces.