fadmuker

THIS IS THE CHALLANGE,
Is there, as there, ever been a muffler that will get my moki 135
under our club noise limit of 79Db without cooking the engine or chasing the needle
engine guru`s please help

if you should choose to take this assignment jim, make contact,
this thread will self distruct in ten seconds

its fun to fly funfly

RaceCity

79dB? Gads.....

I have a wristwatch that's louder than that.

Perhaps it's time to design your own? Mac's header....mousse can...a slotted insert (baffle)....

A baffle can be made from a piece of aluminum arrow shaft with numerous holes/slots cut in it. Part of the tube extends outward from the rear of the muffler, and the rest extends all the way to the front. Exhaust gases expand into the mousse can and fidn their way through the slots/holes to the exit.

Experiment!

'Race

fadmuker

racecity,
thanks for the reply,
been there done that!
bought the cake ate the tee shirt
88dB BACK TO THE DRAWING BOARD
is it possible? or am i chasing a unicorn ?

ITS FUN TO FLY FUNFLY

RaceCity

KEEP EXPERIMENTING!!!!

The lightbulb wasn't successful the first 100 or so tries either...now look!

Get creative!

Good Luck!

fadmuker

your right !
wacko diddly

RJConnet

I have heard some electrics that wouldn't make that 79 dB limit. What are some of the guys in your club using that do make that kind of limit.

RJ

fadmuker

rj connet, thanks for the reply,
four stroke`sat 79dB
i have a leo 37 @ 76dB
tt42 gp @ 79dB
os super quiet silencers do the trick but not big enough for the mighty moki 135!!!

flawedexistence

My Feedback: (1)

That's a very unrealistic target for noise supression. Most clubs require something in the neighborhood of 90 dB at nine feet. I really can't imagine any way to get a large 2-stroke like the Moki to comply. Heck, even if the engine was totally silent, the prop noise itself would likely put you over.

fadmuker

over here in uk the B.M.F.A. RULE IS
82dB LIMIT at 7 mts if more than one model is to be flown then 79dB !!!!!CLUB RULES
noise sensitive flying sites we have two for 20 yrs so far!!!

robert

Ahhhh, the joys of flying in the country, and in a bog...no noise, flightline, height, size, or no. of planes flying at once limits.
Anyway, looks like you will need one heck of a car muffler to quieten it down.

Maxime

Use a three-bladed or a four bladed prop... That should help.

And keep experimenting with self made mufflers.

But 79 dbs.....

RJConnet

Just noticed that the 79dB is at 7 meters, thats about 23 Ft over here. Just might be doable with the right prop to hold the RPM down, a good muffler, and soft mount the Moki. You'd be surprised how much the airframe amplifies the noise with a hard mounted engine. Oh yes, is the 7 meters over grass or over a hard surface?

RJ

bla bla

You must talk to Bob Davis (Davis Desiel Fame)
He makes some very nice mufflers (pits stlye + normal) and they work as advertised. Superbly.
Very quiet.. great idle, no big power loss. I was way impressed with that man. Ring him up and start a conversation that'll last for hours....you'll see what I mean.

Kris^

My Feedback: (1)

I've seen .46 sized trainers that would not pass 79dB, yet drown out my big 100-150 cc powered gassers (on canisters and three bladed props) when in the air. I'm at about 90 dB at 8 meters, and the silly trainers are at about 81-82 dB at the same distance. If I am flying and a trainer is in the pattern too, you don't hear my plane at all, but the trainer whines and rasps along as it flies.

Talk about a conundrum!!!

Try a LONG tuned pipe for a Moki 1.80. It will probably bolt right on, and the Pattern guys have to be at 89 dB or less at 9 feet, and are usually about 83-85 with that setup. 83-84 dB at 9 feet is about equivalent to 78-79 at 25.

RaceCity

Kris? Do I know you?

Concord?

Cool