Earthstar Forums

I hope I am not repeating my self, could be another group I started this question.
What ways can you deaden the noise from the prop and engine exhaust?
Hot rodders use DYNOMATTE but I don,t know what it weighs or how effective it would be.
My 503 exhaust tip is cut off directing the exhaust out the side.
Would it make a diffence if I directed the tip straight back through the prop. Or is there a reason it points out and not back?
Thanks
Fred

Remember Mark had mentioned putting pillows in the back. I just saw a new JT2 arrival here, and was drooling over the back panel enclosure. It was upholstered, and I bet it reduces the noise a lot. The Titan guys have also been battle-ing the noise thing.

kb

Hi Fred
If the exhaust is close to the prop it makes a slapping noise on the prop.
the best thing is to point it straight up with a little tiny drain hole in
it so it doesn't fill up your muffler with water when it is parked in the
rain.
Happy Flying
Mark


In a message dated 9/22/2011 6:14:06 P.M. Pacific Daylight Time,
gayford@golden.net writes:




I hope I am not repeating my self, could be another group I started this
question.
What ways can you deaden the noise from the prop and engine exhaust?
Hot rodders use DYNOMATTE but I don,t know what it weighs or how effective
it would be.
My 503 exhaust tip is cut off directing the exhaust out the side.
Would it make a diffence if I directed the tip straight back through the
prop. Or is there a reason it points out and not back?
Thanks
Fred

Hi Kess
I know what you mean. I still drool over my JT2, to bad it is discontinued.
I am sure a pillow would work (Kimberley on the other site said the same thing) but I was looking for a little more of a Rolls Royce approach.
After I get the radio thing sorted out I am going after the noise level. I have a Radio Shack db meter that I am going to mount on the dash looking back and record the readings. slow - cruise - and wide open.
I am then going to mess around with everything I can think of (and listen to suggestions) and then record each try that I make at lowering the sound level. If one thing has no effect out it goes, so only the effective will stay.
I wonder if a wrap over the muffler would help? (like dragsters and funny cars use)
Thanks
Fred

Hi Mark
How would I do that. Could I add an 90 degree elbow to the existing
rotax tip? Would that affect back pressure or tuning?
Or hacksaw the tip off and rotate it straight up and reweld?
Thanks
Fred

Naa, just run your tail pipe out to the wing-tip, noise gone. But then there is the prop noise. Just put a 24" extension to get the prop away from the wing trailing edge, noise reduced.
More useful ideas from your support gang!!

kb

Well golly ge Kess that sounds like a great idea!!!
You first!
Fred

Hi
Do not rap the muffler!!!! The steel will corrode under the rap.
Happy
Flying Mark


In a message dated 9/23/2011 1:39:35 P.M. Pacific Daylight Time,
gayford@golden.net writes:




Hi Kess
I know what you mean. I still drool over my JT2, to bad it is discontinued.
I am sure a pillow would work (Kimberley on the other site said the same
thing) but I was looking for a little more of a Rolls Royce approach.
After I get the radio thing sorted out I am going after the noise level. I
have a Radio Shack db meter that I am going to mount on the dash looking
back and record the readings. slow - cruise - and wide open.
I am then going to mess around with everything I can think of (and listen
to suggestions) and then record each try that I make at lowering the sound
level. If one thing has no effect out it goes, so only the effective will
stay.
I wonder if a wrap over the muffler would help? (like dragsters and funny
cars use)
Thanks
Fred

--- In _Earthstar_Aircraft@yahoogroups.com_
(mailto:Earthstar_Aircraft@yahoogroups.com) , "kessb" <kessb@...> wrote:
>
> Remember Mark had mentioned putting pillows in the back. I just saw a
new JT2 arrival here, and was drooling over the back panel enclosure. It was
upholstered, and I bet it reduces the noise a lot. The Titan guys have also
been battle-ing the noise thing.
>
> kb
>
>
> ----- Original Message -----
> From: Fred
> To: _Earthstar_Aircraft@yahoogroups.com_
(mailto:Earthstar_Aircraft@yahoogroups.com)
> Sent: Thursday, September 22, 2011 6:14 PM
> Subject: [Earthstar_Aircraft] Sound deadening
>
>
>
> I hope I am not repeating my self, could be another group I started this
question.
> What ways can you deaden the noise from the prop and engine exhaust?
> Hot rodders use DYNOMATTE but I don,t know what it weighs or how
effective it would be.
> My 503 exhaust tip is cut off directing the exhaust out the side.
> Would it make a diffence if I directed the tip straight back through the
prop. Or is there a reason it points out and not back?
> Thanks
> Fred
>

I would saw it and re weld it.
Happy Flying
Mark


In a message dated 9/23/2011 1:45:34 P.M. Pacific Daylight Time,
gayford@golden.net writes:




Hi Mark
How would I do that. Could I add an 90 degree elbow to the existing
rotax tip? Would that affect back pressure or tuning?
Or hacksaw the tip off and rotate it straight up and reweld?
Thanks
Fred

--- In _Earthstar_Aircraft@yahoogroups.com_
(mailto:Earthstar_Aircraft@yahoogroups.com) , thundergul@... wrote:
>
> Hi Fred
> If the exhaust is close to the prop it makes a slapping noise on the
prop.
> the best thing is to point it straight up with a little tiny drain hole
in
> it so it doesn't fill up your muffler with water when it is parked in
the
> rain.
> Happy Flying
> Mark
>
>
> In a message dated 9/22/2011 6:14:06 P.M. Pacific Daylight Time,
> gayford@... writes:
>
>
>
>
> I hope I am not repeating my self, could be another group I started this
> question.
> What ways can you deaden the noise from the prop and engine exhaust?
> Hot rodders use DYNOMATTE but I don,t know what it weighs or how
effective
> it would be.
> My 503 exhaust tip is cut off directing the exhaust out the side.
> Would it make a diffence if I directed the tip straight back through the
> prop. Or is there a reason it points out and not back?
> Thanks
> Fred
>

Hey Fred, remember that the drone we hear at cruise and climb has several componens, and one of them is the intake noise, back through the noise transparent air filter. There is a noise supressing airfliter/silencer thing that is used on the 582 and up, and I heard that it is an option for the 503 also, but you have to rejet the carburetors. I was flying my friends Cessna 150 this afternoon, and was amazed how loud those older GA planes can be too. I'm with you in trying to reduce the racket, and I think that every little thing can help, and a bunch of them might be real noticeable. My exhaust tip turns 90 degrees, and is at the back. It also had the after muffler installed when I bought the plane, and it was quieter, at least outside than it is now. I removed it when I did the wing root thing, and probably made my inside noise louder, too. So far, I have a piece of acoustical foam that I've been fitting to plug up the back of the plane. The Gull 2000 is really small behind the tank compared to the JT's, and the tank is where the rear seat is on the JT's also. I'm going to pad the bottom side of the wing, and make, or adapt a leather boot for the aileron push tube. I also don't think that you would get much acoustical supression from a muffler wrap, because my guess is that not that much racket is getting through the thick walls. Oh, then there is the fan, that little overclocked monster that is making it's own racket too. Kimberly on the other site finally resorts to earplugs and ANR headsets.

kb