Ice Fighters

The airman's meanest natural enemy is not fog but ice. Pilots, who do not hesitate to fly by instruments through the thickest fog, still consider a freezing rain unflyable weather. But last week a group of test flyers took off from a Minneapolis field in a specially equipped B-25 named Flaming Mamie, headed straight for a wave of freezing rain. The plane flew through the storm unscathed. When it landed safely at the field, its wings almost as clean as a dentist's fingernails, the plane and crew were greeted by a group of cheering flyers and engineers.

For three winters this field has served as an ice research laboratory for the Army Air Forces' Wright Field Air Technical Service Command. Said one of the watching experts: "The day is in sight when we'll have an airplane in which pilots can just forget ice."

The research station, operated by Northwest Airlines under the supervision of two Army airmen, Major Al Olsen and Lieut. Myron Tribus. has enlisted the help of topnotch U.S. scientists, among them famed Physicist Irving Langmuir of General Electric Co. They began with fundamental studies of water drops. Their newest gadget, designed to show how well a heated wing repels ice at various temperatures, is an odd-looking plane with a vertical wing section, like a shark's fin, on its back. High-speed cameras, mounted in a special plastic turret, photograph water drops as they hit this upright wing, record the speed of ice formation.

Rain drops in the air, for reasons which scientists do not completely understand, may remain liquid at temperatures far below water's freezing point, turn to ice only when they hit a solid such as dust particles or a plane wing. Then they freeze fast. Big drops hitting a plane wing form a smooth, uniform coat known as "glaze" ice; it does not change the wing contours, but its weight may eventually make the plane crash. Small droplets make a rough, pebbly surface, called "rime" ice, which is more dangerous than glaze because it quickly changes the plane's airfoil (the wing shape, on which the plane's ability to fly depends).

The Minneapolis researchers have found that the most efficient wing de-icer is the exhaust-gas heating system for wing edges which is now standard on B-24 Liberators (TIME, Aug. 9, 1943). But this method could not be applied to a propeller, which is just as vulnerable to icing as the wings. That problem was finally solved by electrical heating; a small generator, mounted on the hub of the propeller, supplies current to heating filaments inside the propeller blades.

Testing these and many another device, the base's pilots have made hundreds of flights in the most dangerous icing weather. They still have a few tough icing problems to solve. A particularly baffling one is ice formation on radio antennas. In an ice storm, an antenna thickens like a ship's mast, is soon torn away.

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