From: "Charlie England ceengland7@gmail.com" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Aviation Specific 13B/20B Mazda Front Side
 Housing-pics
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Date: Sun, 2 Aug 2020 19:22:47 -0500
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On 8/2/2020 5:52 PM, Kelly Troyer keltro@gmail.com wrote:
> Group,
>   As stated in a previous  E mail I have photos of a junk lycoming I/O 
> 540 crankcase with the "Dyna 1" mount ring as used by the "Vans" RV10 
> bolted to
> the top mount "Ears"............I machined a wooden plug to fit the 
> the Lycoming rear crankshaft bearing journal and the outer portion of 
> the plug to fit the
> " ID " of the RX8 Renesis front cover seal area...........This was to 
> show if the Renesis cover would fit within the confines of the 
> Lycoming I/O 540 mount
> ring................It fits very well with only the stock Renesis 
> alternator mount (top of the waterpump portion of the cover) needing 
> to be removed and the
> alternator relocated........These photos are too large to go 
> through the forum but I can send them to any of the group that may 
> want to see them via your
> personal E mail address.............Just let me know..........
>
> Best,
> Kelly troyer
>
>
Hi Kelly,

Is the 540 mount ring the same diameter as the 320/360 ring? If not, 
it's not going to help most people who are running 2 rotor engines. If 
you need a measurement on the mount for the smaller engines, I've got 
one hanging in the hangar.

BTW, for the 320/360 engines, the type 2 mount is pretty rare. IIRC, it 
was only used on some light twins and maybe a single or two, that used 
an extended hub constant speed prop.

Which brings up a point that is significant to me. As I mentioned 
earlier, the dyna mount is intended to converge the mounting bolt angles 
at the cg of the engine/prop combination in order for it to be truly 
effective.  It also requires quite expensive mount 'rubbers'. I've flown 
a significant number of hours behind both dyna and 'conical' (straight 
mount) Lyc engines, and the dyna is honestly not worth the extra 
$300-$400 expense. On a rotary, the value should be even less, since 
there's so little vibration.  A 'conical' setup would be dirt-simple to 
design/build, and a full set of the soft parts could be had for way 
south of $50. There are still a lot of conical mount Lycs in 
circulation, so obtaining a mount from a kit mfgr should be a simple matter.

If you want to post the pics on the list, I'll be happy to resize them 
for you; just send them to me the address in my name, above.

Charlie

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