RE: Noise measuring
For F3A (internatianal aerobatic competition class) the following noise limit applies:
"The maximum sound/noise level of the model aircraft and its propulsion device, shall be 94 dB(A)
measured at 3m from the centre line of the model aircraft with the model aircraft placed on the
ground over concrete, macadam, grass, or bare earth at the flight line.
The tolerance of the sound/noise level measurement, is the specified tolerance of the manufacturer
of the measuring instrument.
With the propulsion device running at full power, the measurement will be taken 90 degrees on the
right-hand side, with the nose of the model aircraft pointing into the wind. The Class 1 SLM (Sound
Level Meter) microphone shall be placed on a stand 30cm above the ground in line with the
propulsion device Other than the helper restraining the model aircraft, and the sound steward, no
persons or sound/noise reflecting or sound absorbing objects shall be nearer than 3m to the model
aircraft or the microphone. The sound/noise measurement shall be made immediately prior to each
flight. The sound test area must be located in a position that does not create a safety hazard to
officials and other competitors." (Source: [link=ftp://www.fai.org/sporting_code/sc4/sc4_f3_aerobatics_08.zip]FAI Sporting Code F3A[/link])