Seeing as how I created the well nut mount in question I suppose I might as well jump in here.

I devised it to solve a problem - did it on my own time and have no financial interest. Hard mounting creates severe resonances with the airframe, beam dampener mounts break, commercial rear dampener mounts are heavy and Hyde mounts are pricey for some people, especially pilots trying to get started in Pattern or with cost concerns for other reasons.

The well nut mount will not help much with low frequency vibration. This is typically what you see when the engine is idling at the flight line and you can literally see the plane shaking. A Hyde mount is somewhat better in this regard because it has no limit for radial movement. However, in order to be stiff enough hold the engine in place the Hyde still transmits low frequency vibration to the airframe, though to a somewhat lesser amount than other engine mounts.

All soft mounts help with high frequency vibration to varying degrees. We did quite a few tests with many brands of engine mounts and all worked. We hard mounted several planes and EVERY SINGLE ONE had resonances in the airframe that you could actually hear. In some cases it was a little scary. The issue went away with any soft mount we tested including the well nut mount.

4 stroke engines backfire every once in a while and for these engines I would never use anything but a Hyde mount. As I mentioned, the Hyde allows radical radial movement and without that feature you can take the nose off a plane if the engine has a severe backfire. I've seen beam type dampeners break with a backfire - in fact, you can almost count on it.

The well nut mount reduces vibration to the airframe, costs next to nothing, is simple enough for anyone to make and IMO is the best solution other than a Hyde mount. But, Hyde makes the best engine mount there is. No one has devised a better mount. If you're a serious pattern flyer I recommending getting one. They last "forever" so though the initial cost is high you're amortizing it over several years. I'm particularly fond of the "A" type mount that doesn't need a nose ring. Nose rings are hard mounted to the plane so somewhat defeat the purpose of having a soft mount.

Lee Davis
[link=http://www.piedmontmodels.com]Piedmont Models[/link]