I would like to include isolation mounts for this GAS engine. Along with the soft mounting, I am planning to use standoffs (optional for ZDZ since its rear carburetor). There are a lot of elastomer motor mounts out there; I don't want to invent the wheel. If anyone has used such combination or similar (maybe with or without standoffs) toward reducing vibration airframe, let me know the name of supplier.

thanks.

Call the distributor before you think about rubber mounts on a gasser. If you rubber mount the engine, it'll try to shake the carb and the muffler off it. It may just void your warranty. I've got over 200 flights on a H9 Cap with a solid mounted ZDZ-80 single - no issues.

As a matter of fact their web site features couple of examples where the ZDZ owners are using these type of devices. I used soft mounting devices with my 4 strokes glow engines with a lot of success, they certainly help to attenuate the induced vibration to the air frame. The range of frequencies absorbed depends on the elastomer device to be used. Some frequencies will be not properly attenuated (even amplified if that happens to match a resonance frequncy). I think all the manufactures make its best to produce a properly balanced engine. Nevertheless, no matter how good your propeller is balanced, you will have to deal with some fair mount of vibration.
I am flying a BME 44 and is hard mounted. It was my first GAS engine project, therefore I didn't want to explore this field an used the most orthodox hard mounting method.
With this project I'd like to incorporate previous experience and implement some of the ideas exposed in the ZDZ website.

FYI:
This is their response:

They said that a "soft mount" is not recommended. This will void muffler warranty. Direct hard mounting or a stiff isolation system such as a Hyde mount is preferred.


thanks.

The "vibration" produced by big displacement 4 stroke engines is not from unbalance -but from having the torque input to the prop---at each 720 degrees---- so the prop slows down for most of 720 degrees then takes a big shot --this causes a hell of a kick -and the rotational soft mounts do help soften that kick.
The larger gas engines 2.4 cu in and up -also put out a big kick - but at 360 degree inputs--be it a twin or a single - --if the power is the same - the kick is the same -
In the sizes of the 1.4 cu in four stroke and the 2.4 in two stroke -- a strange thing happens - the kick required to keep the prop moving at say an average 3000 rpm- is really not that different between these two examples
the why --is that as mentioned earlier - the one engine has to hit the prop harder to maintain the same avg speed of the prop at a given rpm.
Now then - adding a soft mount to the two stroke is a great idea--if you can do it and still hold the engine perfectly on line with the crank axis.
That is the trick-
adding soft points at each mount point is usually a bad setup - the engine wobbles easily.
If tho-- you mounted the engine to a wide flat plate - --then put the rubber bits under the extreme corners - the wobble would be more controlled.
From a practical standpoint -this can get to be a pain -
the best bet is to attach the engine solidly to the airframe .
Here is whre the sh-t can hit the fan.
Simply having a big ol chunk of wood hooked to the engine does not insure that the twisting force exerted on the fuselage - does not simply wind up the fuselage and let it spring back each time the engine fires.
If possible - make sure the enge box is solid - does not twist -
make sure the fuselage is as solid as possible - -all the way to the tail.
Some models are simply not good in this test.
I have tried -and it works - cross bracing very light fuselages ( my 2.4 powered models have fuselages weighing under two lbs)- these don't shake .
Is this a bit more work than just glueing together a ARF - by the book?
sure it is - but it also isn't rocket science -- you can -with help from a friend - carefully apply some twist loads to your model -- see if it has an obvious point that is easy to move.
See if a diagonal piece of very small section spruce can be added to stop this movement.
It may well surprise you how smooth the model can be - if the fuselage is simply stiffened and the engine is solidly atached.
My 11 lb models are proving to be very solid and they are all solid mounted engine setups- so being light is not the problem with having vibration -- the construction plays a big part.

Albatross

Mounting your engine in some kind of flexible mount is more or less a standard here in Europe. I guess it's mainly because of the noise issue than anything else. Those working best seems to be what we call the "Hydro-Mounts", a combination of Elastomers & Shock absorbers. Toni Clark in Germany produces several versions for G62's. Check their website: http://www.toni-clark.com/ I've tried it with GREAT success. Less noise, less airframe vibrations.
I just purchased a ZDZ 80 RV and I'm definately not going to "hard mount" it. Graupner have a "Hydro Mount" setup, specially made for the ZDZ 80RV. I've it on order. I can't tell you about its performance but my experience tell me that Graupner will only let well proven products into their product line. There are also other manufacturers. The German ZDZ distributer has customer pictures on his website, some are showing a home made H-M setup:http://www.amelung-modellbau.de look under the 80RV thread.

Rgds Thomas

Here is how I did it wity no problem whatsoever

http://www.geocities.com/traviscouch/extra2.html

The mount you describe is one I referred to -a wide base plate -
If you look at most US kits -there is a narrow mounting base - and some actual work is needed to change to the big mounting footprint-- the rotary setup with the shock - is also familiar -the shock is an iffy setup - the heat from rapid movement can kill these setups .
But yes these can be made to work -
As a little insight - most US modelers are reluctant to even use an actual muffler !- To add the muffler and a special mount - that all stayed together - well - that could be a bit much for the " bolt together and fly " guys.
These guys are not lazy - It is just that NONE of the good sound killing stuff is really popular - or at the moment , required at most fields .

Dick Hansen: I like the idea you have about using cross-bracing and how to check by twisting. I think a lot of these arfs could use some cross bracing, so viabration is held in check, with your method. Thanks Captinjohn

I think that the traditional approach is very welcome by me and everyone else the loves simple solutions. The above mentioned facts and local experience, perfectly support the hard mounting method. Nevertheless, there are always revolutionary ideas that can help to prevent potential issues associated with excessive vibrations. It is nice to see that at least someone else has explored successfully the application of soft mountings devices for gas engines. I think it will be a good idea to have this items locally available. A local manufacturer may want to look at the "Hydro-Mounts" production...
There are problems that we can not see now (other than neighbors complying about our noisy "toys') ; material fatigue, servo failures, mechanical problems, loose off push-roods, broken servo arms, you name it... The consequence are very well known by all of us.

Once again, thanks a lot for all this information, I glad to be subscriber of this forum.

If anyone else has have local experience with soft mounting or "hydro-mounts" devices, let us know.