Robotic Landing Gear

[Redland]

How bad an idea is this Robotic Landing Gear (http://www.darpa.mil/news-events/2015-09-10)

Do the benefits really outweigh the risks of this???

[Peter3127]

Dunno - might mean I could finally land a Squirrel and look like it wasn't an accident. :}

Side thought - would an active damper system (something halfway between this and existing oleo systems) eliminate Ground Resonance once and for all?

I know it's more bits to fail ....

[Gomer Pylot]

Dunno - might mean I could finally land a Squirrel and look like it wasn't an accident. LOL. Nobody alive can land an AS350 gracefully every time. It's possible now and then, with intense concentration, but eventually it will catch you by surprise. Especially with the low skids. I've actually never flown one on high skids. On the low ones, it gets progressively more squirrelly as you get lower, and as the skids touch it tries very hard to move laterally while yawing, and you never know which way it's going to move.

Oleos can lead to interesting events after touchdown. I have no idea how this device would work. I'll definitely let someone else test it thoroughly first.

[Redland]

I think that I am less worried about the extra things to fail than the increased aum, lack of any options to do a run on landing, and potential damage to the underside of the aircraft from landing on uneven terrain.

[Ascend Charlie]

On a 20-degree slope, the uphill blades would be getting awfully close to the ground?

Imagine how it would be if the machine was sitting on level ground, but the gear computer gyro had a runaway and decided it was on a moving ship deck. Rock around the block.:eek:

[Mechta]

Do you think once its landed it can walk itself back into the hangar? :}

[JohnDixson]

AC makes a valid point. Background: US Army slope landing req't for the UTTAS ( UH-60 result ) was to land at design GW on a slope 0f 12 degrees at any angle to the slope, and at 15 degrees laterally ( L and R ). It was clear while doing those tests that any uneveness of the ground, bushes, rocks would preclude a landing as the rotor tip path was ( eyeball ) 2-3 ft off the ground-at the point of gear touchdown, i.e., with the rotor still level.

Peter mentioned mechanical stability ( ground resonance ). Good point for a lot of rotor designs, as the landing gear design plays an important part of the whole damping picture. Thus the question of how to provide that damping in the collapsible structure suggested. Not impossible, but will come at a fiscal, maintenance, and weight price.

The article also included these statements:

"Reduced risk of damage during hard landings, by as much as a factor of five, compared to conventional landing gear

Ship landings in violent sea states"

The expected reaction to these claims is probably: " Whats not to like about this? ". There is good history regarding both subjects. Reducing damage resultant from hard landings requires increased energy absorption, both in the landing gear and helicopter structure ( recall the number of UH-1 transmissions that wound up in the cabin/cockpit area in Vietnam crashes? ). Serious design aimed at reduced hard landing damage points toward changing or should I say, making universal, existing military crashworthiness standards. But neither the civil user community nor the certification agencies have yet to move in this direction.

As to the ship landings in violent seas, while the RN and USN have taken slightly different design approaches, both design approaches provide a strong mechanical connection between the helicopter and the ship following touchdown. USN testing requires 12 ft/sec landings on a 9 degree slope. Don't know the RN req't, but am sure it is similar.

While there is no question that the technology exists to make a flyable version of the DARPA robotic design, there are some practical issues to resolve as well.

[Peter-RB]

It would need a whole new mindset for many PPL(H) with rotor tip separation from hard or (human)soft objects to hit,.. prolly OK for Pro and the mil but still needs a lot of care re Tips, and real uneven ground being attempted leading to problems.... I would say No for Private, but yes to Mil

[Robbo Jock]

A somewhat less weight sensitive application, but along similar lines...
Active undercarriage (https://video-lhr3-1.xx.fbcdn.net/hvideo-xfl1/v/t42.1790-2/11965025_883928915010147_1572556292_n.mp4?efg=eyJybHIiOjUzMS wicmxhIjoxNTk5fQ%3D%3D&rl=531&vabr=295&oh=58d49728244f12d2c2bd08e323203c8f&oe=55F72DFB)

[311kph]

How fast can it run with those legs during running landing?
Keep it simple.

[whoknows idont]

There could be pivoted skids attached to the legs. Or wheels.
Keeping it simple is a great concept and I'm all for that. Although one must say that that ship has already sort of sailed with the whole rotary wing concept.
Interesting idea for sure if it can be accomplished at reasonable weight and proper reliability. I guess Peter is headed in the right direction, even though he left out commercial ops...

@ Mechta: How sweet would that be! :ok:

[Jollygreengiant64]

Westland wasp, anyone?

[Mechta]

Having both skids and supporting legs as an assembly which attached to a central ball joint under the helicopter would achieve much the same thing. It could be unlocked for descent on a sloping surface and locked by the weight of the helicopter settling on it. By limiting the range of angular movement, blade strikes with the ground would be prevented.

A similar approach to that in the video would be to use a system like the Citroen hydropneumatic suspension. This offered damping, self levelling and variable ride height.