Good point Bulent. Anybody have any suggestions or preferences? I would think
sheet metal flanges along side the tubes would be useful for drilling mounting
and composite duct attachment holes. Little cylindrical stud rubber isolators
from Barry might be nice for vibration isolation mounting. These are sold by
MacMaster Carr at low cost. The A10-041 #8 size (8-32 studs) will carry seven
pounds each in shear and 14 pounds each in compression. These are a 1/2 inch
thick and 3/8 inch inch diameter. See the ACRE NL web site for Barry's URL.

Jeff Spitzer volunteered:

Let's not imply that shock mounts will allow a radiator to be mounted to
something that is moving (like a Lamar special firewall shock mount engine
truss)  Radiators should be mounted to stationary structures lest they crack and
fail.

Paul responded:

I don't follow you Jeff. I was planing on mounting mine to a stationary motor
mount with the above rubber mounts and with the wiggins couplings. In the case
of "Lamar special firewall shock mount engine truss" yes it is moving but the
rad could be mounted to it with the same rubber mounts. What is wrong with that
except perhaps for sympathetic vibration modes? The rad will be up around 20 or
30 cps with respect to the engine while the mount should be much lower than that
but maybe not.

I believe the point that Jeff was trying to make is that the many radiator tubes
are thin-walled and full of this high inertia stuff called "water".  Shaking the
whole kit-n-kaboodle is likely to make the radiator welds fail.  So instead of
mounting the radiator to the "Lamar special" engine mount (which isolates motor
vibration at the firewall versus at the motor, and thus the "Lamar special" motor
mount vibrates), mount the radiator to the aircraft structure.

If one has a traditional motor mount (that isolates vibration at the motor), then
I think Jeff is saying it is ok to mount the radiator to the motor mount.

Did I get it right, Jeff?

Since the rotary is smoother running than traditional piston engines, this
vibration may not be an issue after all.

Russell Kent

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