Tonight's Dumb Idea...

[Wayne Galligan]

Earl,

Your absolutely right on the automotive engine mount thing.  The Acuras that we work on have that same type of mount you are talking about.  I have thought hard about trying to make a viscous fluid type mount for my model airplane.  But the size, weight and type  of materials and machining would make it difficult to make in my garage. In order to produce a smooth running single cylinder engine a counterbalance would have to be incorporated.  Thus adding weight and size to our power plants. 
 I am not sure why but my current new plane is super smooth and quite and it is using the same engine,mount,and exhaust system that I had in my old plane(different design).  I am sure it has much to do with the shape and size of the fuse and wings more then anything then the type of mount or engine or its just the right combination of the whole package.

Wayne Galligan

--- Original Message ----- 
  From: EHaury at aol.com 
  To: discussion at nsrca.org 
  Sent: Thursday, February 19, 2004 10:21 PM
  Subject: Re: Tonight's Dumb Idea...


  Lance

  The auto folks spend a lot of time trying to isolate (rather smooth) engines so that our vehicles are pleasant to operate. The fewer the cylinders, the larger the task. A few years ago I was intrigued by a mount design that consisted of an elastomeric material with enclosed chambers of different sizes that were fluid filled and connected by passages that were sized so that the fluid failed to flow (transfer) at certain frequencies. This allowed them to tune the mount for a range of conditions. Somewhat similar to shock absorber technology and possibly applicable toward providing variable dampening to the YS type mount.

  I've wondered if the stretching of the elastomer at high throttle changes the characteristic of the Hyde type mount beneficially. Allowing for some frequency dampening variability over the operating range.

  Certainly resonance issues with mechanical systems are often very complex. Amazing how well we've gotten our airplanes to work by trial and error.

  Earl
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