Agreed Fabrizio. The most interesting thing about generated noise is that our ears will get used to any noise level we fly at. Consider what we used to fly 20 years ago, with the piped 60's turning a toothpick at 17K rpm. Then a concentrated effort reduced noise to the relatively low and pleasant sounds that pattern planes are known for.

Now the problem for pattern people is when some other poorly muffled engine is running at the same time, and it simply overtakes the pattern plane. That used to be the case at my club because some guys insisted on 3D'ing their 35% gassie at the edge of the runway in constant hover. That and a dead engine contributed to one of my pattern models' demise a couple years ago. Never could hear the thing over all that racket, so when she quit, I found myself grasping for air and there wasn't any left.

Luckily, those models have since gone out of favor and we are back flying quietly, for the most part. Until some heli guys show up and insist on flying at 5 feet off the deck right over the middle of the runway, at full speed. That's loud too

I suppose to some, the obvious thing is to get the pattern planes louder. To me, that's the wrong approach. If most everyone flew quietly, everyone would be able to hear their model. M2cw

MattK