Mailing List flyrotary@lancaironline.net Message #66150
From: Charlie England ceengland7@gmail.com <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Aviation Specific 13B/20B Mazda Front Side Housing-pics
Date: Sun, 2 Aug 2020 19:22:47 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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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