Development of a Graphite Horizontal Stabilizer.
Interim technical rept. 1 Jan-30 Jun 73,
DOUGLAS AIRCRAFT CO LONG BEACH CALIF
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The results of analyses and development component tests of the redesigned graphite horizontal stabilizer are presented. The upper and lower skin panels are redesigned with bonded internal stepped-lap titanium doublers at the main pivot and actuator fitting interfaces. The minimum predicted margin-of-safety for the redesigned pivot joint structure is 29 at the first fastener outboard of the titanium doubler. Three development components are fabricated and tested to verify the static and fatigue load capacities of the pivot joint and the static load capacity of the actuator joint. The pivot joint development component attains a static ultimate load of 170. Design Limit Load DLL and a residual static ultimate load of 195 DLL after 12,000 hours of simulated fatigue spectrum loading. The actuator joint development component attains a static ultimate load of 195 percent DLL. The theoretically predicted strains are in good agreement with strain-gage data. The calculated weight of the graphite structure is 183 pounds, an increase of approxi-mately six pounds for the structural redesign, and a reduction of 26 in comparison with the conventional metal structure. Fabrication techniques for the upper and lower skin panels are discussed. Engineer-ing drawings, quality control test results, and the test plan for the second stabilizer unit are included in appendices. Author-PL