birdman2

My Feedback: (105)

Need info;

I am trying to quiet down my 1/3 scale H9
Cap/ZDZ80 single combo with Supersonic pitts
muffler, 26 x 10 Moki prop. Flys great just
too noisy.

It looks like the best way is to use a canister
muffler. I will plan this task for the winter.

For now, it is flying season, and I want to fly
this airplane.

My current task is to get it quiet enough to get
the other flyers at the field to leave me alone
in regards to the extreme noise issue.

My question to the RCUniverse Form is this:

Does any one have any RPM performance data on
the Bison pitts muffler vs the Supersonic pitts
muffler for the ZDZ80 single?

Does any one have any sound level data on the
Bison pitts muffler vs the Supersonic pitts
muffler for the ZDZ80 single?

I may purchase the Bison until I can get the
time to install a canister this winter. I am
trying to determine how much the sound level
will decrease and how much RPM performance
it will cost for the lower sound level.

Thanks for any info in advance.

Regards

Birdman2

luv2flyrc

My Feedback: (6)

I went from the JA pitts to the Bisson pitts and lost 300rpm on a Menz S 26x10 , Didn't take a sound measurement but, I can tell u that it was definately quieter.

U don't mention your prop type/brand but, that also contributes significantly to the noise level.

BTW I now run a KS canister on it and it is both more powerful 500rpm more than with the Bisson and way quieter. This is definately the way to go on this engine.


Mike

birdman2

My Feedback: (105)

Mike,

Thanks for the info.

I went out and bought a sound meter and did
some measurements. Here is what I found.

ZDZ80RV with Supersonic pitts muffler
with Moki 26 x 10 prop. I am running an
intake trumpet. I have about 1 gal of
gas thru this motor. Running the Pensoil
2 stroke oil for breakin. I expect that
once I go to synthetic oil, I will pick up
some more RPM's.

Max RPM's 6600, 99DB's at 25ft.

I figured that the Bison has less exhaust exit
area than the Supersonic, so I restricted
the Supersonic to see what results I could
get without buying the Bison muffler.

When I plugged one of the exhaust pipes I
got the following results.

Max RPM's 6300, 94DB's at 25ft.

I restricted both exhaust pipes equally and
got about the same results.

The IMAC sound rules say you need to be below
96DB's at 25ft when on grass.

One of the other things that finally occured
to me is to just reduce the ATV for the top
end throttle to acheive the desired DB level
since the noise level goes up alot at the
very high end of the RPM range. Can do the
same thing with a different prop that turns
slower. Don't want to overload a new engine.

Looks like I will go to a can muffler when it
will give me better performance and a lower
DB number.

I would like any more info on these canister
setups that I can get. I do want to keep my
engine pointing straight down. I have seen
many going side ways with header pipes sticking
out of the cowel. A nice installation is another
thing I want to have.

Comments welcome.

Birdman2

RC Extreme power

My Feedback: (24)

I am running a ZDZ 80 with Slimeline muffler that was made for Sacks 4.2 that has the three stacks. Modified it too fit the ZDZ.
At 25 ft getting a 92 DB with a 3 bladed prop 24-10 and 5800 RPM.
You can get 200 more RPM with cans but it weighs 1 1/2 pounds more. I don,t think the 200 RPM are worth the extra weight.
Milton

flynbrian

My Feedback: (1)

Put a wider prop on there and it will be alot quieter. Try the NX 26-10, or you could get a 3 blade and that would reduce the noise, but would lose vertical performance and downline breaking.