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Show Carbon on Plane Props Helps Conquer Vibration DAYTON, OHIO. Tiny carbon strips are helping the army air corps at Wright Field to eliminate propeller vibration and increase the efficiency of its sleek new fighting ships. Attached to propeller blades, the strips,'1 ranging about seven-eighths of an inch in length, are connected through a fine wire to a device within with-in the plane which records the propeller pro-peller variation at different speeds. The slight vibration of a normal propeller is recorded in a shallow, wavy line. , Abnormal vibration, however, results in a jagged series of peaks which increase in size as the variation increases. The story is told of serious propeller pro-peller vibration developing in an engine-propeller combination which had been tested, approved, and put into standard service. From the Dattern of vibration lines obtained in a flight test, engineers en-gineers determined that the trouble originated in the motor. The engine was torn down, and it was found that the original gears had been replaced. re-placed. The new gears, white satisfactory satis-factory in tests, varied from the original to such an extent that destructive de-structive propeller vibration resulted. result-ed. When proper gears were installed, in-stalled, the trouble ceased. |