F-4 Beryllium Rudders; A Precis of the Design, Fabrication, Ground and Flight Test Demonstrations
Final summary rept. Jun 1965-Aug 1971
AIR FORCE FLIGHT DYNAMICS LAB WRIGHT-PATTERSON AFB OH
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This report contains a summary of the total effort expended to design, fabricate, qualify and demonstrate by actual flight tests an aircraft structural component constructed of beryllium. The low density and high modulus of this metal is unmatched by any alloy making it particularly attractive for applications where weight and stiffness are critical. Limited ductility does put a premium on proper design and fabrication techniques. One F-4 beryllium rudder, produced to the same configuration and load envelopes as the production aluminum rudder at weight savings of 41.5, was extensively ground tested first to qualify the configuration for flight testing and then to determine additional data on the acoustic fatigue life and residual strength of the damaged rudder. An instrumented flight test rudder, with a weight savings of 34.6 over the production aluminum rudder, made 158 flights over a 39 month time span with a total flight time of 184 hours and 24 minutes under a variety of operating conditions. A maximum recorded load of 205 design limit load 137 DUL was applied to the rudder due to an inadvertent maneuver on the 10th flight however, no serious damage occurred and the rudder was still considered flight worthy when circumstances dictated removal of the beryllium rudder from the aircraft.
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