Inertial Despin Moment Measurements of a Canted Loose Ring during Spin and Nutation
Abstract
Experiments were made on a loose ring model in a spin fixture to check the validity of the theory that predicts the effect of a loose internal component on the flight behavior of spinning and nutating projectiles. The inertial despin moment of the loose ring was obtained by recording the spin rate versus time. During the test, the complete model was allowed to decelerate freely in spin while it was held at discrete coning angles between zero and 600 RPM. The anticipated spin rate at the start of each spin-down was 6,500 RPM; however, sufficient spin power was not always available. Four loose rings were tested. The important polar angle relationship between the cant plane of the loose ring and the yaw plane of the projectile during spin-downs could not be measured. This experimental inadequacy resulted in an insufficient validation of the theory. Initially, in the absence of the cant-plane phase angle measurement, the correlation between theory and experiment was made by assuming a phase angle of 45 degrees. This correlation, made at a spin rate of 3,000 RPM, indicated a general support of the theory by the experiments. The test results, in conjunction with the spin theory, were also used for computation of the loose ring phase angles that existed during the spin-downs. These results indicate an average phase lag angle of approximately 30 degrees, although large variations were observed with spin rate during the spin downs. Averaged phase angles from three flight tests were 34.0, 29.0, and 24.4 degrees.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1980
- Accession Number
- ADA086112
Entities
People
- Clarence C. Bush
Organizations
- Ballistic Research Laboratory