Paul,

   Years ago there were two brothers from Venezuela with a Cozy powered by
  two
   Suzuki Swift engines that were Siamesed together.  They didn't share the
   same prop, but instead used two counter-rotating props.  The prop shafts
   shared the same centerline.  In cruise, they could shut down one engine
  and
   greatly reduce the fuel burn.  I don't see why this idea couldn't be
   applied to the rotary using two 13b engines.  It would require the use of
   belt drives.  I believe Wankel GMBH developed one along these lines they
   called the Wankel Twin-pack.  (discussed in your YouTube video)  I always
   thought that would make a great package for a larger plane if someone
   wanted to spend the time and money to work out all the details.

   Mark


  I've been tossing this idea around in my head, and I really like it.
  (This is why I was asking about reverse rotation and 3d models a few
  days ago).  It seems so neat to be able to have an almost completely
  independent twin setup in a single engine sized package.  The only
  interlink really is the sharing of the engine mount and perhaps some
  bearings in the prop shafts.  Both of those can be designed to a very
  low failure rate.

  I've roughly sketched out a few things, and it seems to me that the
  best way to go about it would be to face one engine forward, and the
  other backwards.  The backwards engine would drive a countershaft off
  the similar to some supercharger setups except off the flywheel side,
  and the forward facing engine could drive the external co-axial shaft.
   I think Mark was right that a belt drive setup would be best.  This
  setup has a couple of benefits over facing both engines the same way.
  First is that you can have the plugs all facing inwards and the
  exhaust and intake facing outwards.  This will make mounting of coil
  packs a bit easier, and will prevent exhaust from one engine heating
  the other up.  The intakes could possibly share a common filter and/or
  plenum depending on how you set them up.  Depending on the mounting
  setup, you may be able to keep the engines a little closer together.
  The countershaft could also provide a great moment arm to resist the
  bending moment from the props

  If one did want to keep both engines pointing the same direction, a
  gearbox type setup with a reverse idler would certainly work.  I think
  it would be more expensive to do that way, and possibly a little
  heavier as well.  You'd have to worry with oiling too.

  Anyone have any thoughts?


  Josh


 Are you talking about twin engines driving a single prop, or a twin setup
 with independent engines, props, etc?

 Kevin Alderman



I'm talking about twins driving separate contra-rotating props.
Basically everything would be independent. It's all the advantages of
a twin in with single engine drag, no yaw on engine out, and no torque
steering on the ground... like the Cessna 337 except both engines and
props are at the same location.

Joshua Jacobs
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