It Doesn't Have Wheels ... But It's Easy To Carry

When a new airliner or bizjet is ready for its public debut, it emerges from a giant hangar in a glitzy roll-out extravaganza. But when you have a very small aircraft and an equally small company, you have to think on a different scale. Tad McGeer, Aerovel's president, recalls that "We started a company called Insitu in 1992 to develop the miniature Aerosonde for long-range weather reconnaissance." Its roll-out - from a proverbial Silicon Valley garage - was "a little push out into the driveway." Aerosonde eventually became part of AAI's product line, while Insitu went on to develop Scaneagle, and was bought by Boeing in 2008 for a rumored $400 million. Lately McGeer's new start-up, Aerovel, has been busy in another garage - this time in Washington's Columbia Gorge - and has now brought another little aircraft out into the light of day. "It doesn't have an undercarriage, so we couldn't do a roll-out," he explains, "but it's easy to carry so we had a stroll-out instead."

Aerovel Flexrotor

The aircraft is dubbed Flexrotor, and it promises some steps forward for UAVs in the 20 kg class. With a 1 kg payload, as is typical for imaging or geomagnetic survey, its range is expected to be more than 1,620 nm, and endurance more than a day and a half. Yet it also has a Aerovel's Flexrotor prototype capability not normally associated with long range: VTOL. "Our interest in VTOL is economic," says McGeer. "Equipment can be made very portable, which is not just convenient but, for some applications, positively enabling."

Aerovel's design is essentially an efficient winged airframe with a large rotor in place of a propeller. For hover, it pitches from wing-borne flight to nose-vertical, and uses helicopter-style collective and cyclic pitch controls. Meanwhile electrically-powered wing-tip thrusters play the role of a helicopter's tail rotor. The main rotor is powered by a single-cylinder 28 cc two-stroke through a reduction gearbox. It is placed forward of the wing in a tractor layout, but aft of a non-rotating nose reserved for an imaging turret or other payload.

This arrangement allows Flexrotor to achieve not only VTOL, explains McGeer, but also fully automated turnaround. "We're designing a lightweight base station for automatic retrieval, parking, refueling, and launch. It should be practical for tough spots, like the windswept, heaving deck of a small boat."

The benefits would be telling for an application like geomagnetic survey. "It's a natural job for robots: flying parallel lines very precisely at low altitude, usually in remote areas. A base station and a bunch of Flexrotors could be shipped into a rough base site, and one person could keep them flying from there with high utilization. That's a formula for getting costs down."

Aerovel's prototype is for work on the powerplant, hover-and-transition control, and automated turnaround. Then, says McGeer, "with luck we might be ready for a user trial with a long-range aircraft late in 2011."

FMI: www.aerovelco.com