By Nick Flaherty
A full size helicopter powered by lithium-ion batteries has taken off in what the developers believe is the first such flight.
The helicopter, a used Robinson R44 modified by Tier 1 Engineering (Costa Mesa, CA), flew for a five-minute cruise flight to 400 feet altitude with a peak speed of 80 knots. "I'm very pleased to achieve this historic breakthrough in aviation," said Glen Dromgoole, President of Tier 1 Engineering in a statement. "Never before has a manned helicopter performed a vertical takeoff, cruise and landing solely on battery power, and we are thrilled to have further achieved 400 feet altitude and 80 knots during our first full test flight."
The Tier 1 Engineering team designed and integrated all of the helicopter sub-systems, which included eleven 700-V, 100-Ah Brammo lithium polymer batteries weighing 500 kg, twin electric motors and a control system from Rinehart Motion Systems in a helicopter that weighs 1100kg. The five-minute flight on September 21 drained approximately 20% of the battery energy, giving the prototype a 20 mile (30km) range.
"We expect to improve the endurance using higher energy density batteries, a more efficient electrical drive system, and ultimately a more aerodynamic airframe," said Dromgoole. "We removed the Lycoming IO-540 internal combustion engine, installed a custom mount for the electric motors and a reduction gearbox to interface with the existing drivetrain but 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 and the battery modules are supported by a lightweight composite panel and attached to the landing gear under the belly."
There are two three-phase permanent magnet synchronous motors which are stacked together to provide redundancy in the event of a motor failure.
The project is funded by Lung Biotechnology to produce an Electrically-Powered Semi-Autonomous Rotorcraft for Organ Delivery (EPSAROD). All flights were accomplished at the Los Alamitos Army Airfield under a special airworthiness certificate in the experimental category. Lung Biotechnology intends to apply the EPSAROD technology to distributing manufactured organs for transplantation to major hospitals with much less noise and carbon footprint than current technology.