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04-28-2018, 02:10 AM
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Join Date: Nov 2009
Location: Cambridge, UK
Posts: 83
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From a European member...
NACA deduced that the propeller noise dominates and that exhaust noise is next in light propeller driven airplanes. Here is a snippet from the summary of this NACA paper:
"Results of this study show that propeller noise dominates engine exhaust noise even though the exhaust noise has a relatively high intensity. It is concluded, therefore, that in order to reduce the outside sound level of an airplane materially, It will be necessary to modify the propeller to operate at low tip speeds and to have a large number of blades. The practical use of this conclusion is a matter of considerable technical complexity involving many compromises. An effective engine exhaust muffler will also be required."
Many European countries charge higher landing fees for noisy aircraft, which drives people to fit smaller diameter propellers (which usually means more blades), propellers that are better damped (wood core or whatever), reduce the maximum propeller RPM (often to 2,500) and fit exhaust mufflers. One supplier of exhaust mufflers is Gomolzig but they are $$$. Another is Liese (also $$$).
EDIT: Forgot to add this "make your own muffler" link.
Also checkout this VAF post - it's about getting a noise certificate on an RV-10 in Switzerland.
Last edited by Raiz : 04-28-2018 at 02:13 AM.
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04-28-2018, 08:40 AM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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Black knob/blue knob?
Rob, you will almost certainly have to take the plane to Lincoln or some other airport to do your phase one------I would be extremely surprised if you get the approval to use your home strip.
Lincoln is great place for first flight/phase I, and after you get comfortable with the plane, mark off the length of your strip and practice takeoff in that distance with the power pulled back, and/or with lower takeoff RPM---- and see what that does for the noise------need someone on the ground for sure to observe/listen.
All you might need may be the black or blue knob------
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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04-29-2018, 11:27 AM
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Join Date: May 2005
Location: Rescue, CA. KROB
Posts: 352
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Thanks for the recommendations everyone
__________________
Rob Lasater
Rv-14 flying baby, yeah.
Paid Dec 2019
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04-29-2018, 11:37 AM
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Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,351
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Quote:
Originally Posted by Mike S
Rob, you will almost certainly have to take the plane to Lincoln or some other airport to do your phase one------I would be extremely surprised if you get the approval to use your home strip.
Lincoln is great place for first flight/phase I, and after you get comfortable with the plane, mark off the length of your strip and practice takeoff in that distance with the power pulled back, and/or with lower takeoff RPM---- and see what that does for the noise------need someone on the ground for sure to observe/listen.
All you might need may be the black or blue knob------
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Mike,
Do you know if the restriction still is removed for Placerville? UP to a few years ago, they would not allow first flight out of KPVF but I believe it was removed.
__________________
Mehrdad
N825SM RV7A - IO360M1B - SOLD
N825MS RV14A - IO390 - Flying
Dues paid
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04-29-2018, 11:50 AM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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I think Dick W. did his phase 1 with the Moose at PVF------might talk to him.
He is across the taxiway and a few hangars east, now flying a C182 or somesuch.
EAA folks might know also?
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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04-29-2018, 02:48 PM
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Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,351
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Thanks Mike.
__________________
Mehrdad
N825SM RV7A - IO360M1B - SOLD
N825MS RV14A - IO390 - Flying
Dues paid
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04-29-2018, 07:16 PM
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Join Date: Jun 2017
Location: Naples FL
Posts: 147
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Yes, and in the late fifties, if you really wanted to PO all your neighbor you would put on steel packs, which were nothing more then a slight interruption to a straight exhaust system. Guaranteed to get you a ticket in twenty four hours.
Today, any self respecting dump truck with a Jake Break is a good ten decibels higher without the traffic violation  Interesting how societies' expectations and tolerances change over time.
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