External Surface Noise Radiation Characteristics of Truck Diesel Engines - Their Far-Field Signatures and Factors Controlling Abatement

1978 ◽  
Author(s):  
Thomas Trella ◽  
Robert Mason ◽  
Robert Karsick
Keyword(s):  
Diesel Engines ◽  
External Surface ◽  
Far Field ◽  
Radiation Characteristics ◽  
Noise Radiation ◽  
Surface Noise

In‐Flight Far‐Field Measurement of Helicopter Impulsive Noise

1976 ◽  
Vol 21 (4) ◽  
pp. 2-16
Author(s):  
F. H. Schmitz ◽  
D. A. Boxwell
Keyword(s):  
High Speed ◽  
Impulsive Noise ◽  
Operating Conditions ◽  
Tape Recording ◽  
Far Field ◽  
Recording Equipment ◽  
Radiation Characteristics ◽  
Acoustic Data ◽  
Noise Radiation ◽  
The Subject

A new and highly successful method of collecting far‐field acoustic data radiated by helicopters in forward flight has been developed, utilizing a quiet aircraft flying in formation ahead of the subject helicopter. The lead aircraft, flown as an acoustic probe, was equipped with tape‐recording equipment and an external microphone. Spatial orientation of the helicopter with respect to the monitoring aircraft was achieved through visual flight reference. Far‐field acoustic data defining the impulsive noise radiation characteristics of the UH‐1H helicopter during high‐speed flight and partial ‐power descents have been gathered with this technique. Three distinct types of impulsive waveforms have been identified and correlated with helicopter steady operating conditions.

Far-field noise radiation characteristics of an afterburning military jet aircraft

2020 ◽  
Vol 148 (4) ◽  
pp. 2702-2702
Author(s):  
Michael S. Bassett ◽  
Reese D. Rasband ◽  
Daniel J. Novakovich ◽  
Kent L. Gee ◽  
Steven C. Campbell ◽  
...  
Keyword(s):  
Far Field ◽  
Radiation Characteristics ◽  
Noise Radiation ◽  
Field Noise
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