Off Airport Landings

[Bladed Sun]

In regards to off airport landings, which would be better, skids or wheels? I guess it would depend on the terrain, i.e sand, grass, rock, etc.

 

I've only flown with skids and I was wondering what everyone thought. Especially, someone who's tried both.

 

Cheers

[delorean]

Skids.......You won't see many EMS ships on wheels (e.g. B222, B230, B430, A109 are usually equiped with skid gear rather than wheels.) The S76 is the only EMS ship I've ever seen on wheels.

 

I've never flown a wheeled helicopter, but I would be interested to see what kind of slopes were allowed. You definitaly would not want to land them in the mud, wet sand, or snow without "Bear Paws" attached.

 

One of the main purpose of wheels on large helicopters in to allow them to taxi away from parking where it could damage other aircraft or property with hover downwash.

 

Think about the math......These are really rough numbers, but a 206, R44, or a medium size helicopter will distribute the weight over at least 300-400 square inches in grass. That's like 7-8 psi at most. With 3 tires, you figure about 75 square inches; that's like 40 psi at the same medium weight helicopter (~3000 lbs.)

[Eric Hunt]

The S76 tyre pressure is 190 psi.

 

On Another Forum, the ex-chief test pilot of Sikorsky posted:

 

Re: S76 & Sloping Ground

The absence of a limit does not signify a limit! The S-76 has no published slope limits because they are not required, and were considered of little real use. I know this because I was the chief test pilot on the S-76 and wrote or edited much of the original flight manual.

The slope capability of a given helo is very dependant on many factors, only a few are the helicopter, so the numbers in the typical flight manual serve as guidelines only. Many helos have rolled over on slopes half that published in the manual, due to those other factors.

For the typical S-76, one can easily achieve 10 degrees laterally on dry paved ground without using full control. The behavior on slopes is very predictable, and the landing gear makes the landing pretty soft and smooth - makes the pilot look good. There is a bit of rotation down slope when the collective is reduced to the bottom, about 1.5 degrees, so the slope looks worse when at flat pitch, on the artificial horizon. At full control, the S-76 is capable of 16 degrees of right wheel upslope and 12 degrees of left wheel upslope, and 8 degrees nose up, and 12 degrees tail up slope. These slope values are extreme, to say the least, and probably not achievable by operational pilots, because at 16 degrees, things look like a mountain goat sees them.

A nose wheel lock is hardly necessary, as the aircraft does not tend to rotate or pivot on slopes, and the pedals are very effective in keeping things straight.

 

Thanks, Nick.

 

A big benefit of wheels on rough ground is that a tripod will always have a steady base, whereas skids can rock and bend on rough ground and cause a lot of consternation.

[Hawkdriver]

I land in every imaginable terrain with an aircraft that is usually around 18500lbs with wheels.

 

With struts and wheels I can also land sooner then expected at about 11.25gs @ 39 FPS without killing anyone.

 

With exceeding any limitations at all with an aircraft below 16825 I can land at 540FPM all day long on flat terrain and 360FPM on sloping terrain.

 

Alot of normal landings would probably bend some skids of the smaller helicopters Ive seen around the sides.

 

No wind 15 degrees nose or right or left wheel up decreasing 2 degrees for each 5 knots of wind.

 

6 degrees nose down with no tailwinds greater then 15 knots.

 

These limits are not extreme and I do them just about everyday I fly pilots in RL progression.

 

As mentioned above slope limitations are a limit of design and many other factors. Eric explained them pretty well.

 

And at the end of the day, I can still taxi into a small FBO without blowing old people and children around!

Edited January 8, 2006 by Hawkdriver

[Spider]

I have over 6000 hours in 10 different types. Of those different types, 3 were equipped with wheels. I have flown Combat Ops in Africa, Seismic in S. America, Geophysical/Geographic Surveys and Core Drill Ops in Indonesia, I have quite a lot of time flying off various ships' flight decks, Fire Fighting in the USA, various Ops in and around airports in the Middle East and Europe, and so on and so forth.

 

With this experience behind me, I'll take wheels over skids, any day.

 

For the various reasons mentioned already in the two previous posts, and for the fact that I find a helicopter with wheels far more versatile for both off airport landings of all types as well as for all on airport operations.

 

Cheers for now,

 

Spider

[Bladed Sun]

I appreciate all the information. I had thought wheels for the stability and versatility, but I had my doubts when you take terrain into consideration.

 

Once again, I thank everyone for the info.

[RotorRunner]

 

 

Here are a couple of photos of an air ambulance with wheels.

Edited January 8, 2006 by RotorRunner

[helopilot2be]

Skids.......You won't see many EMS ships on wheels (e.g. B222, B230, B430, A109 are usually equiped with skid gear rather than wheels.) The S76 is the only EMS ship I've ever seen on wheels.

 

Maryland State Police use Dauphins. They have wheels. And HEMS is their PRIMARY Mission.

 

 

Chris

Edited January 8, 2006 by helopilot2be

[ascott20]

Just keep your brakes on, and wheels are great in the sod... forget that part, and it can become an interesting ride!!!

[flingwing206]

You won't see many EMS ships on wheels (e.g. B222, B230, B430, A109 are usually equiped with skid gear rather than wheels.)

All six of the A109 EMS ships around here are on wheels.

[delorean]

That's pretty cool that you can land in the snow and ugly terrain on wheels--I didn't know if you could that if you didn't have bear paws.

 

Forgot about the 365s all being on wheels too. Now that I think about it, do A109s even come with skids? I can't even remember ever seeing one that didn't have wheels......

 

What about tall grass, crops, etc?? Are there any problems landing in those with wheels? We have high skids on all of our birds, so we can go in up to the t/r. I'm just thinking about all the potential tough weeds/vines that could get tangled in the brakes or extra hardware do there. Or the tall stuff going into the wheel wells and potentially causing a gear extension problem by getting caught in the scissor links.

 

BTW, one more point for the original poster, skids give you more room under the helicopter for operations needing spotlights, microwave antennas, cameras, FLIRs, etc. On wheeled helicopters, you see some of these mounted on the sides, front, or they can be retracted when the gear extends.

[Gomer Pylot]

The B222/230/430 come with wheels, but many operators choose skids because they're cheaper. Using skids is always an economic issue, and has to do with price, both the original purchase and subsequent upkeep. They're also a little heavier, and reduce payload by a few pounds. I fly B412s and S76s, and I'll take wheels every time, especially if uneven ground is possible. Skids don't do well on uneven ground, rocks, or anywhere other than smooth pavement or level grass. A tripod is stable, and the tires will fit between or around most obstables. The tires are also much more stable on slick surfaces, where skids tend to slide around.

[HH60Pilot]

I've got about 1400 hours in wheeled helicopters (600 hours in an HH-3E w/tricycle gear and 800 hours in an HH-60G tail-dragger) landing in just about every concievable condition under the sun, including white outs in the snow and brown outs in the desert. I'll take something with tires every time. I've got several hunded more hours in skids and find that off airport landings with them require more due dilligence with regards to the surface conditions.

 

As Hawkdriver said, you can plant an H-60 and have the tires and struts absorb a good deal of the energy before anything ever gets transfered to the occupants. Sounds like a good reason to have wheels to me and one of the reasons that I liked flying with them.

 

Doug