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Noise levels??

P

Pilottonny

Well Known Member
Hello,

Here in Europe, noise regulations are very stringent. If not equipped with a muffler system you might be stranded, because you will not be allowed to take off between certain hours (and that is not only during the night!)

Also the landing fees depend on the noise level of your aircraft. For example, the landing fees at Nuernberg Airport will be 29% of that of a "not certified aircraft" for a "Erh?hter Schallschutz" aircraft. This means that you will be paying $ 32,- for a single landing with your "straight piped" RV6/7/9, against $ 9,30 if you are "noise reduced" to 8 dB(A) less than Chapter 10 of the ICAO. (so you would be wasting $ 227,- every time you do 10 "touch and go's" !!)

Because we have to do a noise test to establish the noise level of our plane to get an "airworthyness certificate", it is very important to make the plane as quiet as possible. Now, we all know that RV's are not particularly quiet. I contacted Vetterman about mufflers for the RV9. They sell a system with mufflers, but they only reduce about 6dB(A), which, to me, does not sound a lot and it also reduces the power by 4 to 5 hp.

Of course, also the propeller attributes to the noise. As I understand from reading various lists, comparisons, etc. the MT prop is lighter and may be a little slower, but is also more silent than a Hartzell?

Anybody out there, who has got any numbers, information, or tips on this subject?

Regards, PilotTonny

 
God Bless America and Noise

God Bless America, the home of the brave and the free! (Sorry for the nationalist comment but I was overwhelmed with the feeling of being blessed to live in this great country.)

Exhaust noise it the most critical and most in Europe go with a Swiss muffler, a long extended tail pipe through a "glass-pac" muffler. RV's are NO louder than any other Lyc airplane WITH a muffler. Most RV's of course run straight pipes, which is not a option in some parts of Europe.

Swiss Muffler: http://www.piteraq.dk/flight/muffler.html

Search Swiss Muffler:

http://www.vansairforce.com/community/showthread.php?t=9053&highlight=swiss+muffler
http://www.vansairforce.com/community/showthread.php?t=11639&highlight=swiss+muffler
http://www.vansairforce.com/community/showthread.php?t=13082&highlight=swiss+muffler

The down side of course is weight and drag.


Prop noise is not really your big problem on landing, however yes the three blade props may be quieter, Whirlwind and MT. You may want to check the issue with the WW150/151, that is in a current thread. Normal development pains and it sounds like the fix is good, but at the expense of current owners of the WW 150/151. Living in Europe MT is made in Germany so that might be cost effective or convenient.

Good Luck


PS Pilot skill can cut noise, come in steeper with less power may save you many dB's and Euros.
 
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Motorcycle mufflers

You may want to check out high performace motorcycle mufflers, some bikes have as much HP as a lycoming. Ive seen Carbon Fiber used as well, very light if you do some research on line, probably make something work. Try suppertrap co. it worked well on my old four stroke dirt bike.
 
Pilottonny said:
Hello,

Here in Europe, noise regulations are very stringent. (snip)Of course, also the propeller attributes to the noise. As I understand from reading various lists, comparisons, etc. the MT prop is lighter and may be a little slower, but is also more silent than a Hartzell?

Anybody out there, who has got any numbers, information, or tips on this subject?

Regards, PilotTonny
Click to expand...


My understanding is that the primary driver of propeller noise is the speed of the tip, and to a smaller degree its shape.

The ways to reduce tip speed are to reduce diameter, and reduce RPM. More blades mean more drag, but typically smaller diameter and less noise. Pulling back the prop control while in the airport environment can have a large impact on noise as well.

MT props are made and serviced in Europe, which may be an advantage for you. They are available in many configurations, including multiple blades with smaller diameters than equivalent two-blade props.
 
Pilottonny said:
...I contacted Vetterman about mufflers for the RV9. They sell a system with mufflers, but they only reduce about 6dB(A), which, to me, does not sound a lot and it also reduces the power by 4 to 5 hp.
Click to expand...
Tonny,
6dB(A) is really quite a lot. There is approximately a doubling of sound energy for each 3 dB change. So, 6 dB reduction is about one quarter the unmuffled sound energy.

-mike
 
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