U.S. researchers say they've developed robotic legs for helicopters that could allow the hovering craft to take off and land almost anywhere, even on uneven terrain or the pitching deck of a ship.
The legs can alter their position and reach to adapt to surfaces that are irregular, angled or even in motion, researchers at the Defense Advanced Research Projects Agency say.
Despite being some of the most agile of flying vehicles, able to take off and land vertically, hover, and then cruise at high speed, current helicopters have one drawback — they need a stable, level surface to land on.
The DARPA design, developed in collaboration with researchers at the Georgia Institute of Technology, utilized four articulated legs ending in feet with contact sensors that help the legs determine in real time how much to fold in or out to compensate for an irregular landing surface.
That ensures the helicopter remains level on landing, minimizing any risk of the craft's rotor blades touching the chosen landing site, the researchers say.
They fitted the prototype legs to a radio-controlled model helicopter to demonstrate its ability to land on uneven surfaces in tests carried out near Atlanta.
"The equipment – mounted on an otherwise unmodified, unmanned helicopter – successfully demonstrated the ability to land and take off from terrain that would be impossible to operate from with standard landing gear," says DARPA program manager Ashish Bagai.
The technology should allow safe landings and takeoff from terrain that slopes as much as 20 degrees, more than twice the current limits of existing helicopters, he says.
That makes craggy, boulder-strewn or otherwise irregular terrain potential landing and takeoff sites, he explains.
The legs can also provide safer landing on ships in violent seas, he says.
Another benefit of the articulated landing legs – which represent only a modest increase in weight over current designs – is the ability to fold up tightly against the helicopter's undersurface in flight, reducing drag, the researchers point out.
