Battery-Powered Helicopter Completes History-Making First Flight

By MARK KANE

What were the key specifications of the electric helicopter, such as its weights, power system and controls?

The helicopter had a Gross Weight of 2500 lbs and a BEW of 1250 lbs.  A series of 11 Brammo battery modules weighing 1100 lbs completely powered the aircraft.  The flight controls and drive train were unchanged from that of a Robinson R44, although a digital cockpit display was added for pilot management of torque and power, as well as for data logging.

What is the range of the electric helicopter?
The range of the proof-of-concept helicopter tested on September 21st is estimated at 20 minutes or approximately 30 nautical miles.  We expect to improve the endurance using higher energy density batteries, a more efficient electrical drive system, and ultimately a more aerodynamic airframe.

Can you provide us more information about the test pilot who flew the historic flight?
Ric Webb is a commercial helicopter pilot at OC Helicopters. He has 25+ years military service as a member of the air force, navy, army and coast guard.

Tier 1 Engineering: R44 engine bay following the removal of OEM engine.

Who led the design, build and installation effort?
Glen Dromgoole, President of Tier 1 Engineering.

Was this project in partnership with Robinson Helicopters, or any other companies?
There was no involvement with Robinson Helicopters, as we simply purchased a used R44. Design and development partners in the project include Rinehart Motion Systems and Brammo Power. Test pilot services were provided by OC Helicopters.  Lung Biotechnology PBC sponsored the project.

Is the US Government or military involved in the program?
There is no US Government or military involvement in the program other than the permission for conducting test flights at JTB Los Alamitos.

What was the size of the design & build team?
9 persons

Tier 1 Engineering: R44 engine bay with installed electric propulsion system.

How long did it take to design, build and install the electric propulsion system?
6 months. The design effort started in January 2016. The installation was completed in July 2016.

What was the biggest challenge?
Finding a design solution within the certified takeoff weight of 2500lbs.

What modifications were made to the helicopter?
We removed Lycoming IO-540 internal combustion engine, installed a custom mount for the electric motors and a reduction gearbox to interface with the existing drivetrain. No changes were made to drive train or flight control system. The engine bay contains the motor controllers and cooling system for the electric drive components. The battery modules are supported by a lightweight composite panel and attached to the landing gear under the belly.

Can you provide us more information about the electric motors?
There are two three-phase permanent magnet synchronous motors. The motors are stacked together and provide redundancy in the event of a motor failure. The motor assembly, which has a very a high power-to-weight ratio, was installed by one person by hand.

Tier 1 Engineering: High voltage battery system being prepared for installation.

Who manufactures the motor controllers?
Rinehart Motion Systems

What type of battery system is used?
Lithium polymer battery by Brammo, 700 volt, 100 amp-hour.

Why was a Robinson R44 helicopter chosen?
The R44 helicopter has a heavy 500lb Lycoming piston engine. The retrofit with electric motors, weighing a 100lb, provided useful load for batteries.

Are there other similar electric aircraft?
There are fixed wing electric aircraft but we do not believe there is another electric helicopter in this weight class.

Your press release says EPSAROD is an acronym for Electric Powered Semi-Autonomous Rotorcraft for Organ Delivery, but are there any Semi-Autonomous features to the electric helicopter?
There were no semi-autonomous features in the EPSAROD proof-of-concept aircraft flown on September 21st.  The purpose of the aircraft is to demonstrate the feasibility of battery-powered VTOL and cruise for a manned helicopter.  Semi-autonomous avionics, navigation and controls will be implemented later in the EPSAROD development program. The ultimate goal of the EPSAROD Program is to produce electric-powered semi-autonomous aircraft that are capable of distributing manufactured organs to hospitals for transplantation.

Tier 1 Engineering: Flight path of R44 under electric propulsion at Los Alamitos Army Airfield courtesy of Google Earth.

What is the purpose of the electric helicopter?
The purpose is to demonstrate the feasibility electric propulsion; identify key areas requiring further development; obtain performance data on battery, rotor and motor system; and validate our performance predictions. It is the first phase in the development of the EPSAROD.

How many passengers can it carry?
The mission specification for the EPSAROD aircraft is to carry two people and three manufactured organs with a total payload weight of 600 pounds for not less than 150 minutes, including a 30 minute reserve.