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Proteus in flight over Southern California Proteus in flight over Southern California

Photo Number: EC03-0085-3

Photo Date: March 27, 2003

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Scaled Composites' unique tandem-wing Proteus was the testbed for a series of UAV collision-avoidance flight demonstrations. An Amphitech 35GHz radar unit installed below Proteus' nose was the primary sensor for the Detect, See and Avoid tests.

NASA Photo by: Carla Thomas

Scaled Composites' unique tandem-wing Proteus was the testbed for a series of UAV collision-avoidance flight demonstrations. An Amphitech 35GHz radar unit installed below Proteus' nose was the primary sensor for the Detect, See and Avoid tests.


The Proteus is a unique aircraft, designed as a high-altitude, long-duration telecommunications relay platform with potential for use on atmospheric sampling and Earth-monitoring science missions. Designed by Burt Rutan, president of Scaled Composites, LLC, of Mojave, Calif., Proteus is an "optionally piloted" aircraft ordinarily flown by two pilots in a pressurized cabin. However, it also has the capability to perform its missions semi-autonomously or flown remotely from the ground.

The aircraft is designed to cruise at altitudes from 59,000 to more than 65,000 feet for up to 18 hours. It was designed to carry an 18-foot diameter telecommunications antenna system for relay of broadband data over major cities. The design allows Proteus to be reconfigured for a variety of other missions such as atmospheric research, reconnaissance, commercial imaging, and launch of small space satellites. It is designed for extreme reliability and low operating costs, and to operate out of general aviation airports with minimal support.

Proteus has an all-composite airframe with graphite-epoxy sandwich construction. Its wingspan of 77 feet 7 inches is expandable to 92 feet with removable wingtips installed. Proteus is 56.3 feet long, 17.6 feet high and weighs 5,900 pounds empty. Proteus is powered by two Williams FJ44-2 turbofan engines, each rated at 2,300 pounds of thrust.

Flight testing of the Proteus began in the summer of 1998 at Mojave Airport and continued through the end of 1999.

Under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) project, NASA's Dryden Flight Research Center assisted Scaled Composites in developing a sophisticated station-keeping autopilot system and a satellite communications (SATCOM)-based uplink-downlink data system for Proteus' performance and payload data.

Flight testing included the installation and checkout of the autopilot system, including the refinement of the altitude hold and altitude change software. The SATCOM equipment, including avionics and antenna systems, was installed and checked out in several flight tests. The systems performed flawlessly during Proteus' deployment to the Paris Airshow in 1999.

NASA has used Proteus as a testbed for a variety of technologies related to maturing unmanned air vehicles (UAVs) for use in civil applications.

A small Airborne Real-Time Imaging System (ARTIS) camera, developed by HyperSpectral Sciences, Inc., under NASA's ERAST project, was demonstrated during the summer of 1999 when it took visual and near-infrared photos from Proteus while it was flying high over the Experimental Aircraft Association's "AirVenture 99" Airshow at Oshkosh, Wisc. The images were displayed on a computer monitor at the show only moments after they were taken.

In March 2002, NASA Dryden, in cooperation with New Mexico State University's Technical Analysis and Applications Center (TAAC), the FAA and several other entities, conducted flight demonstrations of an active detect, see and avoid (DSA) system for potential application to unmanned aerial vehicles (UAVs) out of Las Cruces, New Mexico. Proteus was flown as a surrogate UAV controlled remotely from the ground, although safety pilots were aboard to handle takeoff and landing and any potential emergencies. Three other aircraft, ranging from general aviation aircraft to a NASA F/A-18, served as "cooperative" target aircraft with an operating transponder.

In each of 18 different scenarios, a Goodrich Skywatch HP Traffic Advisory System (TAS) on the Proteus detected approaching air traffic on potential collision courses, including several scenarios with two aircraft approaching from different directions. The remote pilot then directed Proteus to turn, climb or descend as needed to avoid the potential threat.

In April 2003, a second series of flight demonstrations focusing on "non-cooperative" aircraft (those without operating transponders), was conducted in restricted airspace near Mojave, Calif., again using the Proteus as a surrogate UAV. Proteus was equipped with a small Amphitech OASys 35 Ghz primary radar system to detect potential intruder aircraft on simulated collision courses. The radar data was telemetered directly to the ground station as well as via an Inmarsat satellite system installed on Proteus. A mix of seven intruder aircraft, ranging from a sailplane to a high-speed jet, flew 20 scenarios over a four-day period, one or two aircraft at a time. In each case, the radar picked up the intruding aircraft at ranges from 2.5 to 6.5 miles, depending on the intruder's radar signature. Proteus' remote pilot on the ground was able to direct Proteus to take evasive action if needed.

Based on the preliminary results of both series of tests, project engineers believe that some upgrades would have to be made to both the Skywatch and the OASys detection systems to maximize their effectiveness as collision-avoidance detection sensors for UAVs. Additional flight tests of other types of detection systems, such as electro-optical infrared devices, may occur in the future under a follow-on program in an effort to establish an equivalent level of safety for UAVs to that now required of manned aircraft.

The ERAST Project is sponsored by the Office of Aerospace Technology at NASA Headquarters, and is managed by the Dryden Flight Research Center, Edwards, Calif.

Keywords: Proteus, Scaled Composites, inflight

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