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
