[PDF] Stress Measurements In A Ribbon Parachute Canopy During Inflation And At Steady State eBook

Author : T. A. Konicke
Publisher :
Page : 18 pages
File Size : 19,61 MB
Release : 1981
Category : Aerodynamic load
ISBN :

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This paper describes the results of an experimental study of canopy stresses in a model ribbon parachute. The distribution of circumferential stress was measured during inflation and at steady state for different values of dynamic pressure. Testing was performed in the wind tunnel at the infinite mass condition. Omega sensors were used to measure stresses and were mounted in different ribbons along the gore centerline. It was found that the steady state stress had two maxima of about equal value. One maxima was near the skirt, the other half-way between the vent and skirt. The distribution of maximum stress during inflation was similar to the steady state distribution and the ratio of maximum stress during inflation to steady state stress ranged from 1.25 to 1.75 and was essentially independent of dynamic pressure. The spectral density of the steady state stress measured at several points on the canopy.

Author : William L. Garrard
Publisher :
Page : 66 pages
File Size : 39,75 MB
Release : 1980
Category : Detectors
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This paper describes the results of an experimental study of canopy stresses in bias constructed solid flat parachutes. Stresses were measured in the warp and fill directions during inflation and at steady state for different values of dynamic pressure. Omega sensors were used to measure stress. These sensors were mounted along the gore center lines so that the warp and fill stress distributions could be determined as a function of distance from the vent. It was found that stresses in the fill direction were substantially larger than stresses in the warp direction.

Author : H. G. Heinrich
Publisher :
Page : 6 pages
File Size : 21,36 MB
Release : 1978
Category : Parachutes
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Circumferential stresses were measured on 5-ft flat circular block-constructed solid cloth and ring slot parachutes in a wind tunnel during inflation under infinite mass condition and at steady state. Five Omega sensors placed along gore centerlines and a force link measured stresses and the parachute force versus time. Radial stresses were measured on a 3-ft solid flat circular block-constructed parachute at steady state. Stress measurements were evaluated in view of maximum and steady-state stresses versus location and time, as well as in respect to the parachute force. The measurements indicated strong stress variations, being different for both types of parachutes. In the 3-ft solid cloth parachute, the radial stress was, at certain locations, greater than the circumferential stress.

Author : Helmut G. Heinrich
Publisher :
Page : 26 pages
File Size : 30,22 MB
Release : 1973
Category : Parachutes
ISBN :

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At the 4th Aerodynamic Deceleration Systems Conference, 1973, the development of the Omega Stress Sensor and initial canopy circumferential stress measurements were reported. Following the first success, the Omega sensor was tested under conditions of rapid loading. No dynamic effects were recorded at strain rates up to 100% per second. In the further pursuit of experimental stress analysis, initial measurements of radial canopy stress were made, and it was found that at certain locations the radial stress is as high or higher than the circumferential stress. Finally, exploratory tests were made in which circumferential stresses were measured on a 5 ft model parachute during the periods of inflation and at the following steady state. All tests were made under infinite mass conditions. The stresses were measured versus time, and their instantaneous values vary with respect to time and location on the parachute canopy.

Author :
Publisher :
Page : 185 pages
File Size : 10,95 MB
Release : 1978
Category :
ISBN :

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The Omega sensor was developed for measuring stress in textile and other flexible materials by the Department of Aerospace Engineering and Mechanics of the University of Minnesota and sponsored by the Air Force Flight Dynamics Laboratory. Two studies were conducted by the University which indicated that the circumferential stresses of inflated parachute canopies indicated by Omega sensors agreed with theoretically predicted stresses and also that the stresses measured by an Omega sensor were not affected by dynamic loading. This particular study deals with an in-house test program, designed to measure the circumferential stresses of a model (five foot nominal diameter) ringslot parachute during inflation and at steady state using modified Omega sensors. Slight modifications to the original Omega sensor had to be made due to complications of the tabs tearing during preliminary testing. Five sensors were attached strategically to the canopy of a ringslot parachute and put through a series of low speed wind tunnel tests. The results are presented in detail and provide for the first time actual measurement of circumferential stresses on the surface of a model ringslot parachute. These results, however, can only present the general trend shown in the parachute's stress distribution and not actual stress values due to the inability to calibrate the sensor while attached to the canopy.

Author : Helmut G. Heinrich
Publisher :
Page : 58 pages
File Size : 16,55 MB
Release : 1966
Category : Aeroelasticity
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The stresses occurring in the cloth of a parachute during the period of inflation and at a steady state are calculated for a number of instantaneous shapes that are characteristic of the opening process and the steady state. The method is general and may be applied to any type of parachute built out of solid cloth, concentric rings, or ribbons. The presented analysis is related to canopies consisting of triangular gores but can be extended to other gore patterns. A numerical calculation is made for a solid flat circular parachute during the period of opening and at steady state.

Author : H. G. Heinrich
Publisher :
Page : 23 pages
File Size : 14,94 MB
Release : 1964
Category : Aeroelasticity
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The stresses occurring in the cloth of a parachute during the period of inflation and under steady state are calculated for a number of instantaneous shapes which are characteristic of the opening process and the steady state. The method is general and may be applied to any type of parachute built out of solid cloth, concentric rings or ribbons. The presented analysis is related to canopies consisting of triangular gores but can be extended to other gore patterns. A numerical calculation is made for a solid flat circular parachute during the period of opening and at steady state.

Author : Helmut G. Heinrich
Publisher :
Page : 62 pages
File Size : 41,65 MB
Release : 1965
Category : Parachutes
ISBN :

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The stresses occurring in the cloth of an opening parachute and at steady state are calculated. The method is based on assumed instantaneous and steady state shapes and related pressure distributions. It is general and may be applied to any type and size of canopy built out of solid cloth. The presented analysis is limited to canopies constructed of triangular gores, but can be extended to other gore patterns. A numerical calculation is made for the Solid Flat, Circular Parachute during the opening and at steady state.

Author : H. G. Heinrich
Publisher :
Page : 35 pages
File Size : 11,55 MB
Release : 1963
Category :
ISBN :

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The stresses occurring in the cloth of a parachute during the period of inflation and under steady state are calculated for a number of instantaneous shapes which are characteristic of the opening process and the steady state. The method is general and may be applied to any type of parachute built out of solid cloth, concentric rings or ribbons. The presented analysis is related to canopies consisting of triangular gores but can be extended to other gore patterns. A numerical calculation is made for a solid flat circular parachute during the period of opening and at steady state. (Author).