Silencing model engines

[MrTin]

Over in "another place", model flyers are fretting over the noise made by, particularly, petrol engines and the fact that supplied "silencers" are worse than useless.
Since I know a lot of you guys run engines in shows, can I ask what clever methods you use to keep these things quiet, 2 or 4 stroke?

Martin

 

[vederstein]

Well, when they break on me they sure quiet up.

 

[V22]

Funny that you mention silencers. I had my 2 stroke momentarily run this evening and thought it could really do with a silencer.. I wonder if something like a tube, with an inner perforated tube stuffed with silencer packing (or steel wool?) would do any good? Similar to a dirt bike exhaust..

 

[MrTin]

That's what I'd go for, but then, I make stuff. These Herberts don't seem to want to make anything these days and would rather spend £350(!!) on some bit of kit which is still marginal. The upshot is they keep losing sites because neighbours get on to the council and they're shut down.
It mainly seems to be larger petrols, but 40 size 2 strokes (glows) also cause problems.

Some clever Dick went on about back pressure and packed silencers causing overheating, but I don't know about that. And then there are those who maintain that the noise is not the exhaust but resonance from the airframe, prop and silencer body itself.
I would have thought your idea, with perhaps a long bit of bendy pipe would cure it.
I've never read so much tosh about power, weight, appearance etc. Not everybody wants to fly electric (which can also be noisy), but if they carry on like this there'll be no flying sites left!

I suggested making something, but was ignored totally.

I think stainless pot scourer would be safer than wire wool, in case of ingestion of fine metal fibres.

Cheers,
Martin

 

[Jasonb]

A lot of our engines are not run for long periods and even then not at sustained full throttle so many don't use any form of silencer, I know I don't.

On the slower reving hit & miss engines it tends to be a scale version of the original which is little more than two domed discs with a narrow airspace between

 

[MrTin]

I figured that might be the case.
Oh well, that's their problem. I was going to do model flying, but can't afford the club membership, so it's academic.
I just thought I'd ask.

Thanks,
Martin