X-20 High Temperature Side Window Test Evaluation

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Report Number: AFFDL TR 65-155
Author(s): McGinnis, John C.
Corporate Author(s): The Boeing Company
Laboratory: Air Force Flight Dynamics Laboratory
Date of Publication: 1965-11
Pages: 222
Contract: AF 33(615)-2013
DoD Project: 1368
DoD Task: 136802
Identifier: AD0477758

The purpose of this program was to experimentally verify the X-20A side window assembly and provide experience for improved window design. The objective was to verify the structural integrity of an X-20A high temperature window design in the X-20A flight environment and provide test data to evaluate the design analysis and development procedures utilized. The window was subjected to a low-level boost vibration environment, outward acting (partial vacuum) limit boost pressure of 7.7 psia, and a simulated reentry heating time-temperature history. The window failed during the re-entry temperature cycle. The primary cause of failure was the high temperature gradient through the depth of the window frame of approximately 850 F which exceeded by a factor of 2 the ultimate design value. The extreme thermal gradient caused thermal curvature of the window frame which induced glass curvature in excess of allowable. Measured temperature and deflections are presented and compared with analytical values. A thermal analysis is presented and compared with test values. Deficiencies of the X-20 window design as determined from the test program are pointed out and suggested methods of improvement are given.

Provenance: Lockheed Martin Missiles & Fire Control

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