Wheels or skids?

March 30, 2011 by Tim McAdams

When it comes to landing gear, helicopters have two basic types: skids and wheels. Skid gear is always fixed and wheels can be fixed or retractable. Which one is better depends on the mission the helicopter is performing.

Skid landing gear is simple and lighter weight, so it is the best choice for small helicopters as weight is always a consideration. Also, skid landing gear needs very little maintenance, but the drawback is that ground handling is more difficult. In very small helicopters (such as the Robinson) ground handling wheels can be attached to the skids and the helicopter moved around by one person. Larger helicopters (such as the Bell 206 or AS350) can be moved around with ground-handling wheels, but it normally takes a couple of people. There are a variety of power-assisted tugs and transporters that can help someone move larger helicopters by themselves. Another method of ground handling that operators use is a platform dolly that the pilot can land on and then tug the dolly and helicopter around. However, pilots need to be comfortable with dolly landings as several accidents have happened from pilots misjudging the landing.

On larger more powerful twin-engine helicopters weight is not as big of a concern and retractable wheels make sense. Wheels are nice because a helicopter can ground taxi (as opposed to hover taxi) around other aircraft and people without worrying about producing a high downwash. Retracting the gear also reduces drag, allowing for a higher cruise speed. Attaching a tow bar to the nose wheel makes moving the helicopter around a lot easier as well.

The engineering decision to use retractable wheels or fixed skids is basically a trade off. The retractable wheels give better speed, ease of handling, and the ability to ground taxi. However, they are more complex, require more maintenance, and increase the weight.

Bell 206 with skid gear

Bell 430 with retractable wheels

20 Responses to “Wheels or skids?”

  1. Nick Ahlen Says:

    You left out the third possibility. Wheels that are NOT retractable. I feel they are the best of both worlds. Heavier than skids, lighter than the associated added weight of hydraulics to retract them. Sure more drag, but you can’t forget to put them down! In the H-60 series we have MORE than enough torque to hit 160 Kts in level flight with them down. Many military helicopters use this config and it is a great “compromise”.

  2. Ehud Gavron Says:

    > Skid gear is always fixed

    The original Bell 209 (Cobra AH-1G) had retractable skids. These were replaced by fixed skids in the production variants.

    Googling “cobra retractable skids” finds lots of resources. One such: http://www.aircraftresourcecenter.com/Fea1/001-100/Fea015_Cobra_Snow/00.shtm

    Ehud

  3. Jon Stark Says:

    Running take-off and landing operations (which are helpful when power limited, as from high density altitude) are much more practical and pleasant with wheels rolling than with skids scraping.

  4. pdxpilot Says:

    Good things – I think the A109 looks like an Italian sports car with the wheels retracted – but the A119 loses something with skids. But then there are sleek looking skids like on EC120/EC130 – so sleek they can be protected as intellectual property.

  5. DJ Williams Says:

    You omitted FLOAT equiped helicopters. A varient of “skids” on land but with the added availability of alighting on water.
    Floats can be fixed for everyday use or emergency deployable.

  6. DJ Williams Says:

    In addition to Float equipped helicopters there are also a small number of models that have amphibious hulls with retractable wheels which can alight on water and also land on land.

  7. jim hanson Says:

    I’ve owned a Bell 47, Hughes 300, and currently an Enstrom. I flew a McCullogh certified gyroplane a few times, and ever since, have wished for wheels on the helicopter. As previously mentioned, run-on landings are never a problem–or autos, for that matter. Landings couldn’t be easier–a flare like an airplane and a 50′ (or less) fun-on delivers smooth and predictable landings. You always retain the option of a hover landing, but watching wheeled helicopters do hover landings–they usually aren’t as smooth.

    I know the Bell 47 originally had a 4-wheel gear. It would also make sense for a multiple-blade rotor system–mitigating the chance of ground resonance.

  8. Mike Borkhuis Says:

    Don’t forget about bearpaws that get added to skids for landing on soft fields and/or snow.

    As for running landings on skids, depending on wind, you can have very little run if you do it right.

  9. Mark Says:

    I think they left out one major thing about wheels – ground resonance. They are more susceptible than skids. But that 430 sure looks gorgeous with wheels!

  10. Gerald Pearce Says:

    Pre-dating the Cobra heli, in the early 70′s, the Army built some special SOTAS versions of the Huey. They had retractable skids to allow a large belly mounted antenna to rotate to detect enemy targets.

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