Proteus soars to new heights

Flight Journal, Apr 2001 by Marks, Bob

They say that records are made to be broken, and the crew of the insect-like Proteus high-altitude utility aircraft has gone to new heights to prove that old axiom. On October 25, 2000, pilot Mike Melvill and copilot Bob Waldmiller flew the Scaled Composites Model 281 Proteus to break two existing National Aeronautic Association/Federation Aeronautic International (NAA/FAI) medium-weight jet altitude records. Reaching a peak altitude of 62,786 feet and a sustained altitude in horizontal flight of 61,919 feet over the California high desert, Melvill and Waldmiller easily toppled the Class C-I.E, Group III record set by a Learjet 28 crew in 1988. Two days later, they established an entirely new record by lofting a 1,000kg payload of steel shot to 55,878 feet.

These records were pursued as part of the NASA Environmental Research and Sensors Technology (ERAST) project, which is funded by the NASA Office of Earth Science and the NOAA/DoD/NASA Integrated Program Office. These extreme-altitude flights proved the capability of the Scaled Composites-built, Burt Rutan-designed aircraft to loft sensors to the upper edges of the atmosphere.

Though the Proteus routinely hauls scientific and commercial payloads on high-altitude/long-loiter missions, these were the first ever for the aircraft above 51,000. Even though the Proteus is designed to operate at extreme altitudes with the crew in shirtsleeves, NASA's DFRC Life Support team was available to add an extra margin of safety. The flights were supported by the NASA Dryden Flight Research Center Life Support team, who supplied and maintained the Scaled Composite crews' David Clark pressurized suits.

Like most attempts to push aircraft to the edges of their flight envelopes, these missions were far from uneventful. The fuel load was kept light, and it had to be managed near the aft of the CG limit-no small task with the complicated wet-wing and wetcanard fuel system. The Williams Intl. FJ44-2E fanjet powerplants (almost identical to those on the garden-variety Cessna CitationJet) operated at the absolute edge of their chamber-tested altitude, and this forced the shutdown of one engine, as its compressor stalled in the thin air while being throttled back. While encumbered by the pressurized suits, the low indicated but high-mach airspeed made the flying especially challenging. "We were pretty busy up there," says Mike Melvill, in a typical understatement.

Although NAA volunteer observer and former USAF U-2 pilot Cozy Kline was on hand to supervise the record attempts, they're still unofficial, and NAA/FAI ratification is pending.