This Incredible Plane: Scaled Composites Proteus

There aren’t many aircraft that can literally stop traffic, but the praying mantis shape of the giant composite lifter literally does just that. No one ever figured out what to do about it, though.

Giving it a name for a mythological Greek sea god who could change appearance at will, Burt Rutan originally designed Proteus as a high-altitude, long-operation, optionally piloted telecommunications platform. Its design mission included carrying an 18-foot-diameter telecom antenna system to provide high-speed internet over major cities. Proteus was to be the first of a series of aircraft built by Scaled Technology Works of Montrose, Colorado (a Scaled Composites spinoff company that eventually closed). But by the time Proteus was developed, telecom companies became more interested in ground-based fiber-optic systems. Lacking commercial interest, Scaled Technology Works built only one Proteus. But its story was far from done.

NASA’s Dryden Flight Research Center, seeing Proteus’ potential for its own research missions, stepped in and helped Scaled Composites continue the aircraft’s development. Airborne testing began with its first flight on July 26, 1998, piloted by Mike Melvill, Proteus chief test pilot, and Peter Siebold, Proteus flight test engineer, at the Mojave Airport. Testing continued through the end of 1999. NASA created a station-keeping autopilot and SATCOM system for the Proteus as a part of its Environmental Research Aircraft and Sensor Technology (ERAST) project. In June 1999, Proteus debuted at the 1999 Paris Airshow, completing its last leg nonstop from Bangor, Maine, to Le Bourget.

The aircraft features a tandem-wing, a twin-boom configuration, and two rear-mounted FJ44-2E turbofans, modified for high-altitude operations. Payloads up to 2,000 pounds are attached to the bottom fuselage. Tip sections can be added to or removed from the rear wing or the forward canards to tailor the Proteus’ aerodynamics for various external payloads or for maximum altitude. The aircraft typically cruises at altitudes from 50,000 feet to more than 63,000 feet for up to 18 hours. Notably, Proteus attained a maximum altitude of 62,385 feet in October 2000, earning it a Fédération Aéronautique Internationale Class C-1e world altitude record.

There is no shortage of projects to occupy its schedule—it has flown more than 1,000 flights. Atmospheric research, reconnaissance and surveillance projects; commercial imaging; and small satellite launches all keep Proteus busy. The aircraft requires minimal specialized ground support and regularly operates into and out of general aviation airports, making it a versatile and economic flying testbed.

Proteus’ legacy lives on in Scaled Composites White Knight aircraft, with the wing design and “mothership” concept being two of the most significant contributions to the project.

Designed for only 100 to 150 flight hours (as a proof of concept aircraft), Proteus, which is today owned and operated by Scaled Composites’ parent company, Northrop Grumman, passed the 4,500-hour mark in 2019 and continues to fly an abundance of research missions to this day, proof that a great design sometimes delivers way more than promised, and for much longer, too.