AN ANALYTICAL TREND STUDY OF PROPELLER WHIRL INSTABILITY
Abstract
An analytical trend study was made that extends the work by Reed and Bland in NASA Technical Note D-659 (AD-250 014) and Houbolt and Reed in Institute Aerospace Science Paper No. 61-34 on the precessional instability of a simulated engine-propeller configuration. Primary attention is given to the applications of simplified linear equations which are derived and which define the borderline conditions between stable and unstable motion in terms of damping coefficients in pitch and yaw. The equations apply to the case of separate elastic centers in pitch and yaw, and the results of some studies are included to show the effects of separate elastic centers. For the case of the common elastic center, the paper confirms the results reported in the two papers mentioned previously as to stiffness, damping, elastic-center location, and mass- or inertia-density ratio over a broader range of these parameters than was previously considered. The present study also includes the effects of polar-to-pitch (or polar-to-yaw) moment-of-inertia ratio and the effects of aerodynamic forces on whirl frequency at extreme values of yaw-topitch frequency ratio. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1962
- Accession Number
- AD0274566
Entities
People
- John L. Sewall
Organizations
- National Aeronautics and Space Administration