Just curious. Why do Pattern flyers mount their engines with soft mounts? I can kind of understand with 4-strokes, but why 2 strokes? The airframes that I have seen look stiff enough (very stiff) to handle the vibration.

The main reason is to keep the vibration level to a lower point and try and not place the whole airframe under a high frequency vibration affecting servos, RX, connectors, etc.[8D]

I would have put the main reason as noise reduction. Reduced airframe noise to be exact. Positive side effects are longer servo and electronics life, reduced RX pack power consumption & airframe life would also be extended.

Cheers,
Jason.

I got some directeducation a few years ago in regard to rubber iso mounts....

In a hurry to get my new 38cc gas 2 stroke engine bench run,I didn'tuse an iso mount. The test stand was simply screwed onto my backyard deck railing and engine was started. One should understand how much "dead"woodis in a back yard deck....a couple tons or more which should absorb lots and lots of vibes.Well.......

I happened to be in bare feet during the first couple runs. The buzz to my feet was uncomfortable so I completed the iso mount I was building and did some more test runs. Again in bare feet but this time, the buzz was gone. This really drove the point of soft iso mounts home.

Point is it doesn't matter how much wood the fuse is made from. Vibes from the size engines we run today, will kill the equipment over short time.

One should not confuse the high frequencybut invisible, destructive vibration at full revs of the hard mounted engine with the low frequency, non-destructivebut very visible shake at idle that rubber iso mounts often display. The rubber iso mounts really isolate the airframe well from the engine at revs higher than idle

Don't forget what workhorses pattern planes are. It is not uncommon for a pattern plane to see hundreds flights in a season. The cumulative effects of this is very apparent.

It isn't an overstatement to say that prior to around 2005, rubber iso mounts enabled pattern model size and particularly the light weight of same, as we know it today.....The Hyde mount was instrumental and the best of its type