Effect of Carriage Mass Upon the Loads and Motions of a Prismatic Body During Hydrodynamic Impact
Abstract
A theoretical derivation for the effect of a towing-carriage mass upon the general equations of motion is made for a prismatic body during a hydrodynamic impact. The resulting equations include a correction factor j that depends on the trim and the ratio of the carriage mass to the body mass. The equations can be used at any stage of the impact to determine the resulting loads and motions of the body, including the effect of a carriage mass. Because of the complexity of the equations for the completely general case, it is necessary to choose examples to aid in showing the conditions at which the carriage mass is important. The examples chosen are the V-bottom float with nonimmersed chines and the flat plate with deeply immersed chines. For these example the equations are analyzed at particular stages of the impact, namely, at maximum acceleration and at maximum penetration. At these stages indicative curves are plotted for an infinite carriage mass in one case and with the carriage mass neglected in another. The difference between the two curves shows the maximum possible effect of the carriage mass at the stages selected. The curves indicate that for the V-bottom float with nonimmersed chines the carriage-mass effect is more pronounced at high trims. At low approach parameters and high trims, a carriage mass is found to have an effect on all the coefficients investigated. At the high approach parameters and high trims, the effect of carriage mass on the vertical-velocity ratio, acceleration, and pitching-moment coefficients is noticeable. At a trim of 15 deg and an approach parameter equal to or greater than 1.0 (flight-path angle </= 13 deg), the maximum percentage change in any of the coefficients investigated at the particular stages selected is about 10 percent or less because of carriage-mass effect.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1956
- Accession Number
- ADA377436
Entities
People
- Melvin F. Markey
Organizations
- National Aeronautics and Space Administration