Attracted to unusual and unknown aircraft, I walked past the record-setting Airbus Perlan 2 stretching its 84-foot wingspan across AirVenture’s Boeing Plaza to find out what the large, white turboprop was and why its fuselage was a series of lumps and protrusions.
Grob built the composite G520/G520T Egrett in the late 1980s, when the US government wouldn’t sell the German government any U-2s, said Roberta Vasenden of Av Experts LLC, which own the airplane, and is based at North Texas Regional Airport, just outside of Dallas.
Like the U-2 and Perlan 2, the Egrett, with its 108.25-foot wingspan, is just a big glider, she said. Powered by a Garrett 1759-shp TPE-331-14F-801L derated to 750 shp so it will deliver full power at altitude, this airplane will carry a 2,000-payload to 50,000 feet and stay there for 8 hours. And that’s why it is the Perlan 2’s tow plane. (The duo did a demonstration during the air show.)
The Airbus Perlan 2 is optimized for flight at 50,000 feet and above, and the Egrett is the most efficient and expedient way to get it there, Vasenden said. With conventional tow planes, it would take hours for the glider to find a mountain wave to lift to 50,000 feet and more time for its pilots to find a stratospheric wave that would lift it toward its 90,000-foot goal.
During the 2018 season, Perlan 2 climbed to a record 76,124 feet on September 2, 2018, higher than the published altitude record set by the U-2, and the team hopes to reach 90,000 feet, which surpasses the SR-71’s published record altitude, in 2023.
The Perlan 2 isn’t the only record holder. Signs propped up against its right main gear leg listed the Egrett’s records for Class C-1c turboprops. In September 1988 it set records for absolute altitude and horizontal flight without a payload at 53,574 feet, and time to climb to 15,000 meters (49,213 feet). And in March 1994 it set a couple of absolute altitude records when it sustained an altitude of 51, 024 feet.
The name of the pilot who flew these records was given on the National Aeronautic Association certificate of record that recognized them, Einar Envoldson, who is the founder of the Perlan Project. Not only could the Egrett tow the Perlan 2 to its optimum starting altitude of 50,000 feet, its payload and equipment bays allowed for a reel to collect the towline after the glider let go of it. As the Egrett’s pilot said, “Having a towline flopping around at 50,000 feet is not good.”
Like the Perlan 2, the Egrett is pressurized, Vasenden said. “At 50,000 feet it maintains an 18,000-foot cabin.” The pilot does not need a pressure suit, but the aviator is masked with a pressure demand oxygen system. When not towing the Perlan, the Egrett is carrying all sorts of novel payloads and new technology to altitude.
Its newest effort is the Airbus UpNext Project. One aspect of it is Blue Condor, which will take modified Arcus-J jet sailplanes, one powered by hydrogen and the other by conventional kerosene, to 33,000 feet to analyze the contrails impact on the atmosphere. After release, the Egrett, packed with emission sensors and instrumentation provided by the DLR, Germany’s aerospace center, will follow in the glider’s contrail.
Basically, Vasenden said, the project will determine if the water vapor contrails produced by the hydrogen engine is good for the atmosphere. The tests are upcoming, she said, but in May the Egrett flew the sensors and related instruments, which have never been used before, so stay tuned. — Scott Spangler, Editor