Landing Legs

DARPA never fail to impress, their latest is right out of a Sci-Fi movie, landing legs for helicopters.

Helicopters are incredibly maneuverable in the air, but during landing and takeoff their traditional skid- and wheel-based landing gear requires stable, flat surfaces—surfaces that are often unavailable in helicopter-needy environs such as forward operating areas, ships at sea and natural-disaster zones. Having the ability to land on and take off from angled, irregular and moving surfaces would greatly expand the effectiveness of helicopters across many military and national security missions.

As part of its effort to provide such a breakthrough capability, DARPA has conducted an experimental demonstration of a novel robotic landing gear system. The adaptive system replaces standard landing gear with four articulated, jointed legs that are able to fold up next to the helicopter’s fuselage while in flight and are equipped with force-sensitive contact sensors in their feet. During landing, each leg extends and uses its sensors to determine in real time the appropriate angle to assume to ensure that the helicopter stays level and minimize any risk of the rotor touching the landing area.

“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,” said Ashish Bagai, DARPA program manager. Bagai described the previously unreleased results of the flight demonstration at Wait, What? A Future Technology Forum, in St. Louis.

Along with comprehensive dynamic simulation and structural analyses, the demonstration flight—conducted near Atlanta—indicated numerous potential benefits, Bagai said, including:

  • Reduced risk of damage during hard landings, by as much as a factor of five, compared to conventional landing gear
  • Stable landing and take-off on sloping terrain of up to 20 degrees, more than twice current limits, and on craggy, boulder-strewn or otherwise irregular terrain
  • Ship landings in violent sea states
  • Significant increase in capabilities with only a modest increase in landing gear weight

The robotic landing gear system was developed with funding from DARPA’s Mission Adaptive Rotor (MAR) program, and is now undergoing continued development by the Georgia Institute of Technology.

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The Other Chris
September 13, 2015 6:52 pm

Fantastic! Sci-Fi definitely. Very reminiscent of the Sheathipede-class shuttle landing system from the Star Wars prequels.

Great direct replacement for skids, wonder if they’ll be looking at wheels as well in a Ka-32-like landing system arrangement.

(Star Wars take-off sequence mark at 2h 28m if it does not automark for you)

http://img2.wikia.nocookie.net/__cb20130806044658/starwars/images/5/57/StolenSheathipedeShuttle-CotF.png

stephen duckworth
September 13, 2015 7:44 pm

The adjustable legs concept has been visualized and used before to enable an aircraft to adjust its right on the Fairchild XC-120 . Just reimagine that pod as an ISO container with a detachable nose cone.comment image
https://en.m.wikipedia.org/wiki/Fairchild_XC-120_Packplane

DavidNiven
DavidNiven
September 14, 2015 8:32 am

It would open up a lot more areas for landing your aircraft I wonder if the offshore and energy sectors would be interested as well as the obvious uses for the rescue services.

Brian Black
Brian Black
September 14, 2015 11:17 am

Passengers already show a tendency to run into the rotor disc when approaching or leaving helicopters landed on gentle slopes.

The Other Chris
September 14, 2015 11:19 am

Indeed, successful manufacturers would be daft not to aim for the offshore and ocean support industries.

DavidNiven
DavidNiven
September 14, 2015 11:45 am

@BB

Does this not mitigate the problem to some degree by insuring the aircraft is always vertical?

TAS
TAS
September 14, 2015 2:06 pm

A good idea, a fairly simple one mind you but great nonetheless. Linked to the deck harpoon this could push the envelope considerably for single-spot helicopter operations.

Let’s get a demonstrator on a Wildcat, then add coaxial rotos and a pusher prop…

A Different Gareth
A Different Gareth
September 14, 2015 4:02 pm

If the legs were wing shaped you could have them stick out instead and provide a bit of lift rather than folding right up.

Brian Black
Brian Black
September 15, 2015 9:17 am

@DN

If the aircraft can remain level on a steeper slope, then the ground would rise towards the horizontal rotor disc on one side and fall away on the other.

I don’t think head injuries or decapitations are all that common, but I have heard of military pilots quickly taking off again when attempts to wave folks around to the safe side go unnoticed. Disembarking troops would likely get an instruction. It’s also apparently a concern for search & rescue pilots inland as civilian climbers and hikers are generally more unpredictable around helicopters and have to be watched closely.

I expect this would be very useful on rocky ground where it wouldn’t take much of an uneven surface to make landing dangerous.

The old Lynx and Gazelles usually had a nice flat and soft grassy Irish or German field to land on. Skids though are generally a light alloy tube with a thin steel shoe, and don’t take point loads or hard uneven surfaces very well. I heard of one Lynx in Northern Ireland having a skid replaced in the hover after it returned with a broken skid dangling after slicing through the middle on a rock. I imagine the USMC’s widespread use of skiddy helicopters in Iraq and Afghanistan resulted in a fair few maintenance and repair events.

DavidNiven
DavidNiven
September 15, 2015 1:15 pm

@BB

My point exactly, you will always have the downward slope as a safe area to approach the aircraft if it positions it self with the fuselage perpendicular to the slope and always have a level platform to load/unload for stores, it could open up more areas for landing in both terms of slope and geology.

Benjamin Oliver
September 16, 2015 4:00 pm

Absolutely brilliant!
Needs a bit of work to maybe extend on take-off, just in case of power failure squall gusts, and adsorb impacts.
Also to “sway” with a rolling deck on take-off and landing.
But this right there has such potential, wonder how much it weigh’s?