As people flock to ski resorts in droves and spend eye-watering sums of money on skis and requisite fashion accessories, its more than a little surprising that so few pilots have ever flown airplanes with boards underneath instead of wheels.
Perhaps those who do fly on skis are keeping it a secret once they have become hooked. The attraction is so great that there are a number of pilots from the deep south who make annual pilgrimages to the north woods to land on frozen lakes and play in deep powder snow with little airplanes.
The smooth, cold air and the stunning winter landscape, combined with the ability to explore scenic, remote sites proves to be irresistible.
What You Need
At one time or another, many light airplane types have been on skis. But the vast majority of airplanes have tailwheels, notably the Piper Super Cub and Cessna 180/185 series, something that may be a bit daunting for pilots without any tailwheel experience. If youre thinking of skis for your airplane, its not an inexpensive proposition. Skis must be certified under an STC and be made of stout stuff.
They have to stand up to hard landings on snow and ice, be able to survive hitting some rocks and still be shoved through the air without ruining the aerodynamics of the airplane. (Not that a Cub is all that aerodynamic to begin with, but you need to avoid any extra drag.)
The collateral benefit of such durable design is that there are many very old skis in good shape on the used market.
Careful inspection of the skis and hardware and willingness to replace the bungees that position the tips and worn bogey wheels may allow the purchase of a perfectly good set of skis for about half what a new set would cost.
Installation of the skis for the first time will run about four hours for straight skis and a couple of days for hydraulic or mechanically retractable wheel-penetration skis.
Two Types
There are two major ski designs; the wheel replacement ski and the wheel penetration ski. The wheel replacement ski is just as it sounds. The wheel is removed and the ski is placed on the axle. Special bungee cords are used to hold the ski in position, front tip up.
These are the lightest skis (starting at about 35 pounds for a Super Cub) and extract the least performance penalty. The price of new, straight skis ranges from about $2400 for a Super Cub to $3200 and beyond for Cessnas.
The wheel penetration ski, on the other hand, fits around the landing gear wheel so the airplane can be operated off both conventional paved runways and snow surfaces. Depending on where you fly, the wheel penetration type may be the most attractive, unless youre sure the airplane wont need to see a runway for most of the winter.
Serious skiplane pilots are as opinionated about the materials for a ski as armchair football coaches are about an umpires call. There are still wood skis on the market and in use. We couldnt find anyone making and selling them in quantity, however.
We know of bush pilots who will use nothing but wood because of weight, flexibility and the ability to make repairs in the field, if necessary. Fiberglass/composite skis are widely available and a certain segment of users will use nothing but fiberglass for its ability to withstand shocks and rough surfaces.
Others insist that aluminum skis with steel pedestals are the best. Most all fiberglass and aluminum skis have a high density polyethylene surface (not Teflon) bonded or riveted to the bottom of the ski.
This is to reduce the problem of freeze down, when the ski heats a bit, melts the snow, which then refreezes. The coating thickness varies (its heavy) for the type of duty expected. The plastic is designed to be replaced periodically due to wear and tear.
Keep the Wheel
Wheel-penetration or wheel-skis come in a number of flavors. Fixed wheel-penetration skis have an opening for the main gear tire and the ski is fixed in position so the tire sticks down below the ski about two inches, allowing the airplane to land on pavement.
The aft end of the ski has a small bogey wheel to keep it from dragging on pavement. An airplane equipped this way can land on snow without any problem. However, the slight extra drag of the wheel does prolong takeoff. New, these skis cost from $3500 to $5500, depending on the size of the airplane.
Because of takeoff performance needs, the retractable ski was developed. Many operators depart from pavement or gravel and fly to where they have to land on snow or ice.
For years, pilots were satisfied with retractable skis made by a company simply known as Federal. It eventually was taken over by FluiDyne, which was bought by Wipair, the Inver Grove Heights, Minnesota manufacturers of aircraft floats.
Currently, Wipair makes aluminum and steel wheel replacement skis for virtually every single engine tailwheel and some nosewheel airplanes. Costs range from $5750 to a rather pricey $9000.
The hydraulic, retractable, wheel-penetration ski is still being made, too, but the price tag now ranges from $21,750 to $40,000. For more information contact Finn Vaughan at 651-451-1205.
Retractable skis can be raised or lowered as the pilot desires. All the lines and the pump add a lot of weight, about 70 pounds. A very few are still being sold new for about $20,000 a set.
Used, they run in the $5000 to $10,000 range depending on size and condition. Contact Wipline if youre in the market for these specialized skis. We suspect they are far too pricey for an owner who just wants to sport around some frozen lakes of a Sunday afternoon and are more appropriate for the working bush pilot who takes paying passengers into the outback for some hunting or ice fishing.
Because its always possible to land with the tire extended through the ski slightly, someone eventually figured out that it wasnt necessary to be able to lower the skis in flight and asked why it was necessary to bother with a hydraulic system in the first place.
Mechanically retractable skis are a wheel penetration ski that can be levered down below the tire when the airplane is stopped. The pilot simply lands, shuts down and then hops out with a lever which is inserted into the mechanism in the ski. The ski is forced down below the tire and latched into place.
The force required is relatively minimal and the process takes less than a minute. When and if the pilot wants to raise the skis, turning them into wheel penetration skis, its only necessary to flip two toggles in the cockpit and skis spring back to their original position.
This can be done in flight. At just about $5400, new, for a Cub series, the mechanically retractable skis have essentially killed off the new hydraulic ski market.
Two Sources
There are only two companies making skis in any quantity. Airglas Engineering in Anchorage, Alaska, 907-344-6720 makes fixed, wheel-penetration skis for just about every helicopter and tailwheel airplane imaginable.
It also makes skis for the Cessna 172, 182 and 206. Airglas VP Gary Landes pointed out that while the company does have a web site at www.airglas.com, it does not advertise because its currently production limited, selling everything it builds. AeroSki Manufacturing of Brooten, Minnesota, 320-346-2285 makes wheel replacement skis and mechanically retractable skis for a vast selection of tailwheel airplanes, homebuilts and ultralights.
Gerald Reese has been building skis for years and, as with Gary Landes, not only speaks knowingly about skis, but has some definite opinions about their operation.
The issue of whether to use a tailwheel ski depends on conditions. Many pilots refuse to use them because the ski sacrifices the braking effect of putting a tailwheel deep into the snow by pulling hard on the control stick.
However, in deep powder, a tailwheel ski may be a must, otherwise the airplane will sink until the horizontal stabilizer is on the snow.
In any snow, its necessary to get the tailwheel to the top of the snow when turning, otherwise there is a risk of bending the rear fuselage, a major and expensive repair. Most of the ski manufacturers make tailwheel skis. A new, extra large, wheel-penetration ski has just come on the market from Burls Aircraft Rebuild of Chugiak, Alaska, 907-688-3715, P.O. box 671487, Chugiak, AL 99567 www.alaska.net/~burls.
To get a sense of what ski flying is all about, visit a small airport in the northern tier. Unless you are in Anchorage, those who fit skis on their airplanes shun big airports.
Youll find quite a number of airplanes on skis, but if you have the opportunity to fly a ski-equipped airplane to a remote lake, you may find yourself making a phone call to Airglas or Aeroski and ordering a set for your airplane.
Also With This Article
Click here to view the Ski Checklist.
Click here to view “Ski Technique: Fly With an Expert.”
-by Rick Durden
Rick Durden is an ATP-CII, attorney and a regular contributor to Aviation Consumer. He lives in Michigan.
