Why do landing wheels need so much room. Let's design a new one for helicopters.

Not your usual topic in this forum but don't laugh just yet.

Think of a large sectioned Hydraulic ram pointing down. In the end we put a captured hard rubber ball that can rotate in any direction. This replaces the wheel.

When in flight, the ram is contracted and is within the airframe.

When deployed, the ram travels down, section by section and the fluids are designed to compress for the landing shock.

Now the Helo can move on the ground in any direction, including 180 degree turns on the spot, great for close parking.

A smaller Ram within the Ram provides the ability to brake. That bit is not hard.

With Rams deployed, the aircraft could self level to a degree making landings on slopes easier.

For jet aircraft, directional control could be by differential braking.

Ok, shoot me down.

P

"Rotate in any direction"

Bearings?
What's holding it in?

a reply to: a325nt

Take apart a bearing and see for yourself.

Only about a third of the ball is 'outside' of the ram end. It is 'captured.'

P

I spent nearly half of my life on the flightline. I have watched veteran fighter pilots spend 20 minutes, trying to parallel park a car. Your idea gives them control of a multi-million dollar fidget spinner. It would be like the Olympic Games... fun to watch, but an economic disaster in the end.

a reply to: madmac5150

They do have brakes.

If you want to // park, just tilt the rotor in the direction you want the whole airframe to move in.

P

something for the department of redundancy department...

originally posted by: pheonix358
a reply to: madmac5150

They do have brakes.

If you want to // park, just tilt the rotor in the direction you want the whole airframe to move in.

P

Ground crews will have to practice "duck and cover" with every noobie zippersuit, for their first dozen sorties. On the plus side, PT scores will improve...

Detractors all.

Anyone want to actually think critically rather than zoom zoom comments?

P

a reply to: pheonix358

Wheels are designed the way they are for a reason. It spreads the footprint out and minimizes the stress on the tarmac and runway. If you minimize that footprint, it puts all the weight into a small area, and maximizes the stress on ground under the aircraft. The HH-60G weighs 16,000 pounds empty, and has a maximum takeoff weight of 22,000 pounds. The CH-53K has an empty weight of over 33,000 pounds, and a loaded weight of almost 75,000. Putting that on a system like you're describing would put all that weight directly under the aircraft, on a tiny area. It would crack the tarmac under them much quicker.

a reply to: Zaphod58

I see your point clearly.

What about the decks of ships that are designed for the load and the same could be said of a tarmac if it was designed to take such a load.

Or you could try a pneumatic ball that will disperse the weight over a greater area.

P

A helicopter's movement is vertical, up and down created by collective air force, thus lift or descent movement in any direction is a matter of falling in that direction, to be controlled by lift/collective and prop tilt.The facing direction controlled by a secondary prop determining direction by + or - collective. Wheels are redundant. There are variations and numbers of prop configurations.

originally posted by: pheonix358
A smaller Ram within the Ram provides the ability to brake. That bit is not hard.

How would that work exactly? Just ramming it into the rubber ball? The ball would go up in flames when trying to slow down. Also as soon as you add any kind of friction forces your large sectioned hydraulic ram pointing down would buckle.

For jet aircraft, directional control could be by differential braking.

I don't see that working. The wheels also provide directional stability. Using differential braking instead would be a control nightmare, would have to be automated.

As mentioned the general issue though is that the ball would have to be large enough to not damage the runway. So it probably would not be much smaller than a wheel.

a reply to: pheonix358

Take a Physics class and the rethink your idea.

wheels on a helicopter are about aircraft handlers moving it on the ground, without it being powered. the whole point of a helicopter being able to take off from a standstill, without needing to use a runway. and in fact doing as the OP proposes would actually make the ground crew's jobs harder since using such a system would mean the helicopter would be a pain to move in any one direction. rather like shopping carts where all 4 wheels are on castors.

originally posted by: pheonix358
Not your usual topic in this forum but don't laugh just yet.

Think of a large sectioned Hydraulic ram pointing down. In the end we put a captured hard rubber ball that can rotate in any direction. This replaces the wheel.

This is all well and good until the wheels touch down and the plane is pushed sideways off the ramp when landing

How exactly is the hydraulic -pneumatic-whatever ram designed for the necessary stresses going to take up less room than the oleo/ram in conventional landing gear?

a reply to: wtfatta

On top of some the other thoughts. Generally, designs take ease of maintenance into consideration, an over complex system adds to downtime and expense. Any new design does not only have to function properly it's design manufacturing and maintenance has to be much more or reliable and cheaper than existing designs.

Lots of things can be designed and coaxed to work, but in real-world applications, it needs to cost-effective and reliable

a reply to: pheonix358

An interesting thought is that the solution that nature has come up with as almost universally the most efficient one for it's flying bilogical machines are legs.

Yet we seem to be stuck with wheels or skids because we have only been making them for around a century.

We have yet to duplicate most of what nature does, even when it comes to flying, where nature has produced "machines" that can do incredible things.

When the oxygen content of our atmosphere was greater, nature even produced some very large, very efficient flying machines, none of which flew the way we design our machines to fly. And none of which have wheels.

a reply to: pheonix358

A locking caster would be a better idea.

originally posted by: pheonix358
a reply to: a325nt

Take apart a bearing and see for yourself.

Only about a third of the ball is 'outside' of the ram end. It is 'captured.'

P

Bearings aren't made of rubber though, it sounds like you're taking about making a rubber ball/wheel using a metal bearing design, is anybody making rubber balls for this purpose anywhere? It makes sense with metal but I don't see how it makes sense with rubber, the properties are a lot different, especially if the rubber is a hollow shell filled with air, and if it's solid rubber instead, that's a very poor landing gear design with only a single point of contact.

originally posted by: pheonix358
What about the decks of ships that are designed for the load and the same could be said of a tarmac if it was designed to take such a load.

Why would you want to spend a fortune upgrading tarmacs to use balls instead of wheels when the wheels work fine with existing tarmacs? I don't understand why you would even suggest that.

Landing on a ship might not be a problem for the ship, but if that's the only place you can land it's a very limited capability helicopter even if you can figure out how to engineer your idea of a bearing made out of rubber.