INVESTIGATIONS ON THE DYNAMIC STABILITY OF PERSONNEL GUIDE SURFACE PARACHUTES
ADVISORY GROUP FOR AERONAUTICAL RESEARCH AND DEVELOPMENT PARIS (FRANCE)
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In order to investigate the dynamic stability of a parachute the system of the non-linear equations of motion is derived. In contrast to previous contributions this system of differential equations is non linearized, but is integrated by means of electronic computers for a number of examples of personnel guide surface parachutes. The influence of the suspension line length, the effective porosity of the canopy, the weight of the load and the apparent mass on the dynamic behaviour are studied for the examples chosen. The results show that the oscillations of parachutes cannot be described by linearized equations of motion. For instance, only the nonlinear procedure enables the complete description of the velocity oscillations. Furthermore, it becomes evident that frequency and damping depend on amplitude. For some amplitudes the square of the oscillation period is proportional to the length of the suspension lines. With increasing porosity of the canopy the damping increases and the oscillation period decreases.
- Gliders and Parachutes