Aircraft Systems
The DragonFly is a 12 foot wingspan radio-controlled airplane. It has a 2-stroke engine with a shielded spark plug. The radio receiver is shielded and located away from the avionics as well as its own battery pack in order to reduce interference. The avionics are placed into the fuselage.
The DragonFly can fly with or without the avionics as a remotely piloted vehicle. In addition to four GPS antennas and the IMU the DragonFly has airspeed and wind direction indicators. It also has a low power onboard video system which transmits to ground for video recording of test flights.
The DragonFly Project utilizes a large (12-foot wingspan), heavily-modified, radio-controlled model airplane. 
The plane features 4 GPS antennas on its upper side and a 5th GPS antenna on its lower side for updates during large maneuvers. The GPS data provides information about the aircraft's attitude, position and velocity.
In addition, the system features a special GPS receiver engine developed jointly with Trimble Navigation, Ltd. 
This receiver is a unique design which combines 5 parallel, 8-channel GPS receivers on one board together with one common reference oscillator. This receiver engine is stacked with a an embedded single board VersaLogic 5x86 computer.
The single board computer facilitates the integration and synchronization of data feeds from GPS sensors, inertial sensors and many analog sensors. The single computer operates with the real-time operating system QNX
The system also features a 
Honeywell HG1700 inertial measurement unit (IMU). This tactical grade unit features 3 ring laser gyros and offers relatively high accuracy, small size, low weight and low power consumption.
Inertially-aided GPS results from the combination of GPS data with data from inertial sensors. Inertial aiding enables the GPS receiver to reacquire signal lock rapidly and loose lock less frequently. It can also make the receiver resistant to jamming. Over all, this arrangement provides for a much more robust control system that is reliable through large vehicle maneuvers.
The avionics box encapsulates the single board computer, GPS receiver board, DAQ, IMU and the IMU interface boards, radio Modem, and additional expansion boards. It is built with a common PC architecture - modular and expandable.
Ground telemetry is facilitated by Freewave
spread-spectrum transceivers. These radio modems transmit at 115Kbaud and operate in the 902-928 MHz range. Several data streams are transmitted to the ground for subsequent processing and analysis.
The Actuator Control Computer switches control from the ground pilot to the autopilot and vice-versa.
The DragonFly runs off of two NiCad battery packs. Here Chris Carlson charges up the packs in preparation for a flight test.
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