| 摘要 |
PROBLEM TO BE SOLVED: To positively prevent recirculation of exhaust gas without using a special exhaust duct, thereby perform an exact confirmatory operation test without generating low-frequency noise, and safely and correctly perform the confirmatory operation test without allowing head wind to flow into noise insulation chambers even when the head wind is particularly strong. SOLUTION: The run-up noise reduction system is made up of a airframe noise insulation chamber 12 the height of a ceiling 12a of which is lower than a vertical tail plane 1a of an aircraft 1 and which has an open groove 12b through which the vertical tail plane is projected upward, a tail-unit-noise insulation chamber 14 of an angle shape, which closes the open groove 12b to accommodate the vertical tail plane 1a inside, a vertical exhaust-noise reduction chamber 16 which is provided in the rear of the aircraft, closely following the airframe-noise insulation chamber and the tail-unit-noise insulation chamber to guide exhaust gas backward and upward, and an intake air-noise reduction door 11 which is provided on the front side of the aircraft to close the whole of the front of the airframe-noise insulation chamber to introduce air into the airframe-noise insulation chamber. The passages of the intake air-noise reduction door 11, the airframe-noise insulation chamber 12, and the vertical exhaust- noise reduction chamber 16 are smoothly connected to each other, and the passage-cross sections are formed to be nearly the same.
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