This might not be of great concern of most RV-10 owners especially in the US but I consider this still an important environmental information for all the RV-10 owners.
My RV-10 has been built and accepted under Swiss regulations and one part of it is the noise measurement certificate. Landing tax are based mostly on MTOW plus a charge for the noise class your aircraft is in. So it was of great interest to achieve the lowest noise class.
As there was no data available about noise emission of an RV-10 I want to share my findings.
The main noise sources are the propeller and the engine noise via the exhaust system. As prop tip speed is one factor I decided to go with a smaller diameter 3-blade MT (MTV-12B/193-53) propeller. The next factor is of course RPM which I reduced to max 2500. It is quite common for GA aircraft in Germany or Switzerland to have RPM reduced to 2500 in order to meet the maximal allowed noise requirements. The next thing is the exhaust system/muffler. There are special mufflers available like Liese which are quite common to muffle the noise even further, however I needed my baseline first to make the call to install them or not and to be able to define its required dB reduction.
My RV-10 has the standard Vetterman 6-3 exhaust system and the above called 3-blade prop running max 2500 RPM. The test were conducted at MTOW 2700lb /1225kg.
ICAO Noise Measurement Test Scenario
ICAO Annex 16 Chapter 10
- Application accepted from 1988 onwards
One measurement point
take-off flight path with max. take-off power
Noise measured in dB(A)
The measurement crew on the ground takes a picture of the overflying aircraft to compare the logged overflight altitude reported from the aircraft with the measured results. At the same time it measures the noise. More factors are taken into consideration including wind, surrounding surface etc. I had to conduct 6 flights and the average noise values plus the correcting factors result in the final noise level in dB, which puts me in one of the noise categories mentioned above.
To make a long story short my RV-10 achieved 77.5 dB which falls under category D, which is the lowest available.
It is interesting to note that the only other RV-10, which went through the same test, is equipped with an two place Hartzell propeller (as well reduced to 2500 RPM) and Liese mufflers attached to the Vetterman exhaust pipes, achieved noise class C. Therefore it looks as if the propeller diameter and probably the tip form is a major contributor to noise. There might be other contributing factors such as sound insolation which might work as a reduction of resonance.
For all the builders who are building under a regulation where noise reduction is a topic I hope that might help to consider propeller choice besides looks, ground clearance and weight.
Michael
My RV-10 has been built and accepted under Swiss regulations and one part of it is the noise measurement certificate. Landing tax are based mostly on MTOW plus a charge for the noise class your aircraft is in. So it was of great interest to achieve the lowest noise class.
As there was no data available about noise emission of an RV-10 I want to share my findings.
The main noise sources are the propeller and the engine noise via the exhaust system. As prop tip speed is one factor I decided to go with a smaller diameter 3-blade MT (MTV-12B/193-53) propeller. The next factor is of course RPM which I reduced to max 2500. It is quite common for GA aircraft in Germany or Switzerland to have RPM reduced to 2500 in order to meet the maximal allowed noise requirements. The next thing is the exhaust system/muffler. There are special mufflers available like Liese which are quite common to muffle the noise even further, however I needed my baseline first to make the call to install them or not and to be able to define its required dB reduction.
My RV-10 has the standard Vetterman 6-3 exhaust system and the above called 3-blade prop running max 2500 RPM. The test were conducted at MTOW 2700lb /1225kg.
ICAO Noise Measurement Test Scenario
ICAO Annex 16 Chapter 10
- Application accepted from 1988 onwards
One measurement point
take-off flight path with max. take-off power
Noise measured in dB(A)
The measurement crew on the ground takes a picture of the overflying aircraft to compare the logged overflight altitude reported from the aircraft with the measured results. At the same time it measures the noise. More factors are taken into consideration including wind, surrounding surface etc. I had to conduct 6 flights and the average noise values plus the correcting factors result in the final noise level in dB, which puts me in one of the noise categories mentioned above.
To make a long story short my RV-10 achieved 77.5 dB which falls under category D, which is the lowest available.
It is interesting to note that the only other RV-10, which went through the same test, is equipped with an two place Hartzell propeller (as well reduced to 2500 RPM) and Liese mufflers attached to the Vetterman exhaust pipes, achieved noise class C. Therefore it looks as if the propeller diameter and probably the tip form is a major contributor to noise. There might be other contributing factors such as sound insolation which might work as a reduction of resonance.
For all the builders who are building under a regulation where noise reduction is a topic I hope that might help to consider propeller choice besides looks, ground clearance and weight.
Michael
Last edited: