Contra Electric Propulsion Ltd., announce the completion of design and specification for their new electric CRPS 260 GT aircraft propulsion system.

The system comprises two 160kW (peak power) electric motors driving two fixed pitch contra rotating propellers via a coaxial shaft arrangement housed within a power transfer box. 

Quarter Scale Engineering Model of CRPS 260 GT showing power transfer box, twin motors mounted to rear and twin contra rotating propellers (cut down).

The power transfer box forms the structural element of the propulsion system and is designed to be mounted to the firewall of an aircraft with a conventional “engine” frame.

All subsystems including battery packs, inverters, cooling systems and ancillaries are duplicated to provide a true twin “engine” system either of which is capable of maintaining flight in the case of a motor or electrical systems failure. Although classified as a twin engine system pilots will not be required to hold a “twin rating” to operate the equipment as the two propellers are coaxially mounted. Stopping one causes little asymmetric flight.

The system has a continuous rating of 200kW (250hp) but with a peak power of 320kW (400hp) for one minute, can offer many aircraft an upgrade from standard take-off and climb out performance to full “STOL” performance.

This is because the almost instant full power response of the electric motors and the yaw-free thrust generated by contra rotating propellers eliminates the four “swirl” effects experienced by single propeller aircraft during take-off.

These effects, yaw (slipstream effect) and asymmetric wheel drag in aircraft with tricycle undercarriages and in addition asymmetric blade effect and tail wheel drag in tail wheel types, severely limit the ability of single propeller aircraft to undertake short take-off and landing (STOL) operations.

The system can be configured as a pure electric system or incorporated within a hybrid combustion and electric architecture and has a full reverse thrust capability. Retrofitting the equipment to aircraft currently fitted with single propeller systems of the same power will greatly improve the aircraft’s overall performance in flight.

Ground and air trials of the system are scheduled for 2020 and 2021 installed in a purpose modified RV 4 Harmon Rocket in partnership with Condor Aviation Limited at Birchwood Air Field.

Uncertified systems for installation in experimental and permit aircraft will be released in 2021. Excluding batteries, the complete propulsion system will weigh 125kgs and cost (excluding battery pack) will be £95k, competing favourably with similar power single VP propeller piston installations.