Vibration Characteristics of Aircraft Engine-Propeller Systems 390185
COMPLETE isolation of the airplane propeller from the engine, except for a very flexible torque drive, appears to be the only satisfactory solution of the vibration problem in the future, Mr. Kearns believes. Under such conditions, he explains, much lighter propeller blades can be used to maintain even greater horsepowers than are available at present so that, in spite of the trend toward more power, the increase in overall weight of the powerplant may be delayed considerably.
This problem of the vibration characteristics of the engine and propeller when operating jointly, he points out, recently has become practically the determining factor in the selection of the proper propeller for use with a given airplane-engine combination. An intensive investigation of this problem, studying both experimental and analytical approaches to the causes and solution of the high-stress conditions found in some engine-propeller combinations, is reported.
In his paper, Mr. Kearns discusses the various sources of excitation and resultant modes of motion frequently found in present-day powerplants. He also points out some of the present methods of treating vibration problems and mentions possible future developments in this direction.