Prolific aircraft designer Burt Rutan has emerged from a brief retirement to unveil a new seaplane design he claims can seat two people, fly up to 2,100nm (3,890km) non-stop, survive a 10g impact on rolling seas and fit inside the one-car garage of his lakeside home.
Any other retired aircraft builder might invite scrutiny – if not intense scepticism – with such claims, but Rutan has a reputation for defying traditional limits with the non-stop, round-the-world flight of the Voyager, the first private suborbital flight of SpaceShipOne, endurance record-setter GlobalFlyer and 43 other novel designs.
Indeed, Rutan credits his own record for driving him to make a new seaplane – named the SkiGull – that exceeds the range and efficiency of most land aircraft, but which is flexible enough to operate from water or land.
“I did Boomerang and Voyager. Why would I do something for a seaplane that was just a little better?” Rutan said, addressing an audience in late July at the Experimental Aircraft Association’s AirVenture fly-in in Oshkosh, Wisconsin.
After selling his ownership stake in Scaled Composites to Northrop Grumman in 2007, Rutan retired to his home in Coeur d’Alene, Idaho. Inactivity appeared to suit him at first, but after 18 months he returned to his lifelong vocation of dreaming up exotic new aircraft.
Moving from Scaled Composites’ desert headquarters in Mojave, California, to the banks of an Idaho mountain lake, it was perhaps inevitable that Rutan’s interest would be drawn to aircraft that could operate on water.
But the design of the SkiGull began with Rutan listing all of the annoyances about seaplanes that he wanted to overcome.
Some were as simple as installing shock absorbers. Noting that most seaplanes land on rougher surfaces than fixed wing aircraft yet lack a device to attenuate the load, Rutan seemed incredulous: “It’s all backwards. Why in hell have people not put shock absorbers on a seaplane? They’re the only guys that need it!”
The SkiGull will not only feature retractable skis with shock absorbers, the airframe is also designed to survive a 10g impact on water. Rutan formed that requirement after envisioning the SkiGull slamming into the crest of a 12ft-high wave while landing on a rough sea. If the pilot could survive that impact up to 10g, Rutan wants the aircraft to survive it as well.
To enable enough range to fly non-stop from San Francisco to Honolulu, Hawaii, Rutan designed the SkiGull with a 14.3m (47ft), strut-braced wingspan and what he calls the world’s most efficient aircraft engine: a Rotax 912IS.
Another Rutan peeve with seaplanes is the lack of power, with an engine-out on take-off especially risky if it is necessary to clear trees beyond the lake. So he is installing an auxiliary electric power system that can provide an extra 30% thrust increase on take-off. The aircraft also can fly in cruise mode for about 7nm using electric power alone. In water, the electric power system can also be used to manoeuvre the aircraft to the dock.
Rutan emphasises, however, that he has not yet flown the SkiGull, and so the claimed performance remains unproven. An attempt to assemble and test the aircraft ended in failure about three weeks before the AirVenture event, when Rutan realised the skis would have to be redesigned.
Source: Flight International