Experiments in External Noise Reduction of ... - CAFE Foundation
Experiments in External Noise Reduction of ... - CAFE Foundation
Experiments in External Noise Reduction of ... - CAFE Foundation
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.26rNACA TN 2079 “APPENDlxGROUND AND SER%CCE TESTS OF VE?KBELT DRIVEFOR CONFIGURATION 4Ground TestsGround tests were made with the fuselage staked down at theMetropolitan Airport, Canton, Massachusetts, dur<strong>in</strong>g the months <strong>of</strong> Junethrough Septeniber1948. The conditions <strong>of</strong> these tests were’as follows:(1) Fifty hours at 1500 eng<strong>in</strong>e rpm, about 20 horsepower. Beltslippage occurred emly <strong>in</strong> these tests but was cured by tighten<strong>in</strong>g thebelts after 3 or 4 hours <strong>of</strong> runn<strong>in</strong>g. ow<strong>in</strong>g to the coarseness <strong>of</strong>adjustment, they were probably made a little too tight.(2) Full-throttle tests at2450eng<strong>in</strong>erpm, about 103 horsepower. .These tests were started without readjustment <strong>of</strong> the belt tension.After 5 hours, one belt failed by breakage <strong>of</strong> the cable. This was theshortest belt <strong>of</strong> the group. After this failure the adjust<strong>in</strong>g mechanismwas ‘alteredto give a f<strong>in</strong>er adjustment and the belt center distance wasreduced by a smsll amount. Six hours at full throttle on the rema<strong>in</strong><strong>in</strong>gn<strong>in</strong>e belts were then completed without failure.I,Flight ExperienceSubsequent to the ground tests, and beg<strong>in</strong>n<strong>in</strong>g on September 15,1948, the modified. Cub airplane, configuration 4, wak assembled andflown for purposes <strong>of</strong> the sound-level tests reported here<strong>in</strong>. For these .tests a new set <strong>of</strong> belts was used. The eng<strong>in</strong>e power was limited toabout 75 to 80 horsepower at full throttle, level flight (see table II)by mesm <strong>of</strong> a throttle stop. Total.fly<strong>in</strong>g time under these conditionswas 425 hours.6w<strong>in</strong>g this time 3 belts (belts 3, 5, and 8) turned over, but weresubsequently used after be<strong>in</strong>g turned back <strong>in</strong>to their grooves andtightened. The condition <strong>of</strong> the belts at the end <strong>of</strong> this time is asfollows: Belts 2, 3, and 5 T?erefrayed; and belts 6> 7> 9> ~d.lo wereloose and showed signs <strong>of</strong> deterioration. On November 26, a third set<strong>of</strong> belts was <strong>in</strong>stalled and%ad been run for l— 1 hours when a telegram from‘Goodyear Aircraft Corporation ad?rised”usto discont<strong>in</strong>ue use <strong>of</strong> that setbecause <strong>of</strong> poor quality. The fourth set’was <strong>in</strong>stalled on DeceDiber17._——.
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