Observations on Parachute Scale Factors for Modeling Parachute Deployment and Steady State Performance.

摘要

A New approach to the scaling of parachute performance is presented, based upon variables inherent in the inflation process such as weight, time, geometry, etc. Limitations of conventional scaling parameters such as Reynold's, Froude, and Mach numbers as applied to parachutes are discussed. Examples of parachute inflation and steady state performance are correlated with a scale factor designated as a Mass Ratio, which is the ratio of the system mass to a mass of atmosphere associated with the parachute size, inflation time, altitude and deployment velocity. For advanced opening shock analyses, the concept of variable mass ratio during canopy inflation is proposed, and the effects of partial canopy inflation at suspension line stretch are discussed. Although the solid cloth types of parachutes are primarily used as examples, the ideas of mass ratio, initial area, and analysis techniques are applicable to all types of parachutes. (Author)