Helicopter and Cable Drop Tests of a Multi-Sensor Yawsonde Instrumented SADARM Model
Abstract
A series of helicopter and cable drops of a yawsonde-instrumented SADARM model was designed to determine the flight behavior of the parachute/ warhead system under conditions which would resemble both a real flight environment and a feasibility firing environment. About ninety percent of the helicopter and cable drops resulted in successful deployment of the vortex-ring parachute and proper operation of the system. Tests with the 2.13-metre parachute show that steady-state spin is achieved about four seconds after release for both cable and helicopter drops. The average spin rate observed with this parachute is 4.7 rps + or - 0.1 rps. The yawsonde results showed that this particular model/parachute combination has a bi-modal yaw behavior. The slow mode has a frequency equal to the pendular frequency of the system (about 1.0 Hz). This mode seems to be excited by external forces such as wind shear. The fast mode has a frequency about equal to the steady-state spin rate (about 4.8 Hz) and this mode appears to be excited by the dynamics of the parachute/payload system. The fast mode does not appear to be damped. From the yawsonde data, the amplitude of yaw seems to be about 5.0 degrees. Use of 1.83-metre parachute and smaller torque disk with this payload appears to increase the duration of the transitional time to about 7.5 seconds. Also, the average value of the steady- state spin is increased to 6.0 rps. The bi-modal behavior of the system remains unchanged although with the smaller parachute the frequency of the fast mode is increased to about 6 Hz. The slow mode remains unchanged.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1981
- Accession Number
- ADA100798
Entities
People
- V. Oskay
- W. H. Mermagen
Organizations
- Ballistic Research Laboratory