Engineering topics
Publications and source records attributed to Liebers, F.
The available literature on rotating propeller oscillations reveals a lack of uniformity in interpretation, particularly as concerns the data on the overtone frequency with respect to the centrifugal forces. The present report is a survey of the existing data for computing the bending frequency and a check on the dependability of the calculating methods.
This report presents a calculation of the torsional frequencies of revolving bars with allowance for the air forces. Calculation of the flexural or bonding frequencies of revolving straight or tapered bars in terms of the angular velocity of revolution. Calculation on the basis of Rayleigh's principle of variation. There is also a discussion of error estimation and the accuracy of results. The author then provides an application of the theory to screw propellers for airplanes and the discusses the liability of propellers to damage through vibrations due to lack of uniform loading.
The report discusses the problem of rating the various seaplane designs from the 1926 seaplane contest. The whole process of rating consists in measuring the climbing speed, flying weight and carrying capacity of a seaplane and then using these data as the basis of a construction problem.