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Thanks Mark and Tracy for the info. I'll check out
the foam.
Charlie,
My 6A had minimal interior upholstery, my -4
has none except seat cushions. The 6A was a little drafty and a little noisy,
but not all that bad. The -4 canopy isnt leak free by any means, but seals way
better than the 6A. In the 6A my old Lightspeed 20K ANR headset worked fine but
in the -4 with the radio volume cranked all the way up I have trouble making out
radio calls. The -4 is WAYYYY louder than the 6A was. The Lightspeed Zulu I
borrowed a couple of weeks ago was better, but I could still use
more.
My muffler fairs into the cowl pretty well.
I'd guess that it would be pretty tough to come up with a better aerodynamic
solution for the muffler than what I have now. Extending the tailpipe is
something I'm considering. Maybe not the best choice for aesthetics, but if it
helps its probably worth it.
Mike Wills
RV-4 N144MW
----- Original Message -----
Sent: Saturday, September 12, 2009 5:59
PM
Subject: [FlyRotary] Re: cockpit
soundproofing
> Agreed. The extension idea was to just extend the pipes so the ends
are
> behind the cockpit. I think that Tracy actually had something like
that
> for a while & mentioned that it made the cockpit
quieter.
>
> I have no proof, but I suspect that turning the pipes
down can, in some
> situations, actually add noise & heat to the
floorboards due to the
> induced turbulence whipping the exhaust back
against the floor & also
> causing drumming on the floor. My Lyc
powered RV-4 has downturned pipes,
> & the floor is so hot I'm pretty
sure I could cook pancakes on it.
>
> Mike, Since you've flown RV's
for a while, you may already be aware of
> this; a lot of the higher
frequency noise can be minimized in the
> cockpit by just sealing up all
the air leaks into the cockpit. The 1st
> -4 that I owned was painful,
even with a Lyc. Sealing up the air leaks
> around the canopy made it
easily tolerable, even with passive headsets.
>
> FWIW,
>
> Charlie
>
> Mark Steitle wrote:
>>
Charlie,
>>
>> You're correct, turning the pipe down
does add drag, but so does
>> hanging a big square suitcase shaped box
under the fuse. It just
>> depends on how badly you want to
quiet things down.
>>
>> Mark
>>
>>
>>
>>
>> On Sat, Sep 12, 2009 at
3:03 PM, Charlie England
>> <ceengland@bellsouth.net <mailto:ceengland@bellsouth.net>>
wrote:
>>
>> Mark Steitle
wrote:
>>
>>
Mike,
>> My first
line of defense against the noise is an ANR
headset.
>>
That's a
given.
>> I
purchased some black foam from ACS that I installed on
the
>> interior walls
and floor. From what I've read a lot of
the
>> noise comes in
through the firewall and windows. Not much
you
>> can do about the
windows, but it seems that a generous
amount
>> of
soundproofing on the firewall will help the most.
Lastly,
>> you can turn
the exhaust down so that it is directed away
from
>> the
occupants? Or, run it back behind the pax, and fly
faster
>> than the
speed of sound so it can't catch up to you. Mark
S.
>>
>> On
Sat, Sep 12, 2009 at 10:15 AM, Mike Wills <rv-4mike@cox.net
>> <mailto:rv-4mike@cox.net>
<mailto:rv-4mike@cox.net
>> <mailto:rv-4mike@cox.net>>>
wrote:
>>
>>
I asked a few days ago and got no replies. Since things
are
>> a
bit
>>
slow on the list now I'll try again. Anyone have
any
>>
recommendations for a decent soundproofing material that
I
>> can
add
>>
to my firewall and floorboards to tame this racket?
Maybe
>> the
rest
>>
of the world will have to deal with the noise, but at
least
>> I
can
>>
try to make it a little more pleasant for
me.
>>
Mike
Wills
>>
RV-4 N144MW
>>
>>
>> Running
it back past the occupants can actually be
effective.
>> Turning it down adds
drag.
>>
>> I've often wondered why no
one has tried carrying the pipes down
>>
several inches below the fuselage before turning them aft,
and
>> installing streamline inserts aft of the
downpipes & between the
>> fuselage bottom
& the horizontal run of pipe, to get smooth
air
>> between the fuselage & the
now-parallel exhaust stream.
>>
>>
Charlie
>>
>>
--
>> Homepage: http://www.flyrotary.com/
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>>
>>
>
>
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>
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>
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