Spoilers, Slots, Burbles

To Langley Field, Va. from Newark one day last week flew Col. Lindbergh in the new Northrop Gamma transport mail plane which TWA's Vice President Jack Frye piloted from coast to coast three weeks ago in 11 hr., 31 min. (227 m.p.h.). Also to Langley Field went some 200 other leaders of U. S. aviation, including Orville Wright, for the ninth annual aircraft engineering research conference of the National Advisory Committee for Aeronautics. Run off with precise showmanship by affable, grey-haired Dr. Joseph Sweetman Ames, committee chairman and president of Johns Hopkins University, the conference developed from a year's research these facts & fancies:

Retractable spoilers are curved structures extending up from the upper surface of the wing, which when combined with "air brake'' flaps, make lateral control easier.

Suction slots through which a fan inside the wing sucks air, control the thin stratum of air ("boundary layer") next the upper surface of the wings, increase lift 150% using only 2% of a light airplane's power.

Compressibility burble is a phenomenon which appears at speeds of 500 m.p.h. or higher. Plane speeds have not reached the point where "compressibility burble" has become a practical limiting factor, but propeller tip speeds are near it. "Compressibility burble" is a sharp break away of the airflow from the upper wing surface like the bow-waves of a ship, leaving the air directly behind extremely rarefied.

Flutter of wing or tail surfaces may wrack a plane to pieces when it reaches a certain periodicity and intensity. With military planes approaching 300 m.p.h., wing flutter has become a major problem. The committee has developed a method of foreseeing and guarding against structural fatigue and failure.

Poor man's plane was called for by Director Eugene Luther Vidal of the Department of Commerce Aeronautics Branch who declared: "It should be possible to buy airplanes at the cost of automobiles."

Because its full-scale wind-tunnels and other elaborate testing-devices make it the world's most completely equipped aeronautical research plant, NACA's Langley Memorial Laboratory conducts many a history-making aeronautical experiment. Created by act of Congress in 1915 "to supervise and direct the scientific study of the problems of flight," NACA has 15 members who serve without compensation. Of its $900,000 general appropriation for fiscal 1933, NACA spent $600,043 for "personal services," $1,545 for "transportation of things," $960 to rent an office in Paris. Of President Wilson's original appointees, there remain only Dr. Ames and Dr. Charles Frederick Marvin, 75, retired chief of the U. S. Weather Bureau.

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