ORIGINAL: BaldEagel
Quote from MVVS thread 10 April 2007:
"Pe
You may remember I bought the MVVS isolation mounts from you some time ago, well I have now unsed them in my 2M Extra and can report that far from the popular belief that iso mounts increase vibration these are so efffective a pal of mine who is also a petrol head could not belive the lack of vibration in this instalation, In a normal hard installation the tail or wings will vibrate up and down at tick over and only smooth out when you advance the throttal, in this case the plane is smooth all through the rev range and just sits still at tick over with no vibration noticable at all, obviously the work done installing the anti vibration mounts was very worth while, none of the screws used to mount the cannopy, cowl or anything else have moved thoughout any flight, My pal was so inpresed he did not stop going on about it all day, he is now a convert."
They also reduce noise, I did start a noise reduction thread on the gas forum, but no one was interested, but for interest the difference between a Brison warp around and an MTW 75 was 7Db that is a big reduction.
MIke
Mike, this is the technical side of the coin, do not expect many responses here. Where it hurts, is that sometimes models are not allowed to fly just because they are 2dB too loud. 1 dB is still considered twilight zone, and (just barely) accepted by those who know what they talk about. Nazi type field marshalls are NOT in this league.
BTW folks, and all bitter jest aside:
dB are calculated on a logarithmic scale so:
1dB is what a TRAINED ear can hear
3dB is double noice perception
10 dB is tenfold (10^1)
20 dB is 100-fold (10^2) of noise perception.
There is much more to it, but I do not want to confuse with knowledge littering. This is as KISS as I dare to go.
So the 7 dB reported by Mike is a VERY VERY LARGE noise reduction, just by using the MVVS iso mounts. Beyond that, you need to attend to airframe resonance, prop noise etc. It is the hardest noise that blankets the lower ones. Once addressed, another one pops up it's ugly head and shouts: "see to me"first!!.
Engine vibe isolation effectiveness depends a lot of airframe mass, and stabilasation by the wing (like a taut rope dancer). Large scale planes, with much frame and wing mass will not notice it much, but 3D planes will. (the engine is bolted to a seismic mass) (OK, this is not KISS, but a little advanced)