Condor: An All Electric Airplane

Boeing has designed and built an unmanned experimental Autonomously Piloted Vehicle called Condor, which has successfully flown. The flight control surfaces are operated using four basic types of electromechanical actuators (EMAs). A common controller design is used to operate all EMAs. This airplane utilizes only electrical secondary power to operate all the subsystems in the vehicle. So it is truly an “All Electric” airplane. This paper describes the Condor flight control actuation, propulsion control actuation, and electrical power generation and distribution systems. Each propulsion system is controlled by a single full authority digital Control Electronics Unit (CEU) with electrical actuators. A separate electronic Ignition Control Unit (ICU) drives the spark plugs, processes camshaft position sensors, and sends speed signals to the CEU and the mission computer. The electrical system consists of two engine-mounted 270 Vac oil cooled brushless hybrid homopolar generators that utilize high energy permanent magnets. The 270 Vac generator output is converted to 135 Vdc and 28 Vdc power by a dual output converter/regulator. The majority of the airplane loads are operated from the 28 Vdc power buses. The 135 Vdc power primarily is utilized for operating the flight control actuation system. Uninterruptible power is provided for operating the flight-critical equipment from the 28 Vdc flight-critical bus which is backed up by a battery with diode isolation. This paper also presents some of the pertinent flight test results for the electrical distribution system. There were no significant problems with the all electric flight control system during the eight test flights of the airplane.