Conversion of High Modulus Materials into Flexible Fabric Structures
The designs of numerous re-entry drag or lift-drag devices incorporate a flexible, low porosity, thermally durable membrane. The missions anticipate temperatures in the range of 1500-2500°F and strengths of 20-50 pounds per inch width. The necessity of being able to package and subsequently deploy these devices demands a membrane with good bending recovery.
The possible flow patterns over and heat transfer to a porous, fibrous structure in a re-entry environment were examined. The expressions for a theoretical estimate of the heat transfer increase to the structure were developed. Unqualified statements of the precise heat transfer increase as a function of structure are not possible in light of the obvious need for experimental verification. However, the theoretical investigation indicates that a moderate porosity can be tolerated under some flight conditions without a significant temperature increase.
The feasibility of stranding and plying into yarns metal filaments as fine as 0.5 mil and subsequently weaving the yarns has been shown. The fabrics obtained were flexible, thermally durable and had very low porosities.
A possible application of the metamorphic principle was demonstrated by the high temperature exposure of a fabric woven from a composite yarn composed of a chemically treated organic yarn and 0.5 mil metal filaments.
At the present time further investigations leading to the development of high temperature durable, flexible, strong, "fabric-like" structures utilizing high modulus of elasticity materials in both filamentous form and other configurations are being carried out.
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Symposium on Fibrous Materials
ASD TDR 62-964