Innovative In-Flight Aircraft Noise Measurements

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Jentink, H.W.
Meulen, M.P. van der
Tump, R.S.
Brouwer, H.H.
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Netherlands Aerospace Centre NLR
NLR developed and tested a new method to measure the noise of aircraft engines during a flight. NLR’s Cessna Citation research aircraft has been equipped with a nose boom which catches the noise of another aircraft nearby. With this method the noise of an aircraft engine can be measured more extensively compared to flyover tests and adds to windtunnel tests. The feasibility of the chase aircraft acoustic in-flight measurement method was demonstrated in a small experimental test campaign in which NLR’s Cessna Citation II (C550) research aircraft is measuring the noise of a Cessna Supervan (C208) propeller aircraft. Two types of acoustic sensors have been tested and measurements have been taken from several directions and at several distances in different flight conditions. The operational procedures for the flight test campaign were developed and proved adequate. The noise of the propeller aircraft was measured with the microphones on the boom of the chase aircraft.