Paul -- Have you designed a Bearhawk Engine Mount?
  Bearhawk is designed for 180 to 250hp powerplant. I'm
 building as light as
 possible, so 180 to 200 hp Renesis is the goal.The
 Bearhawk is
 designed at 6.6G Utility, 2500 pounds.
  http://www.bearhawkaircraft.com for more details.
  Tom Walter
  Not yet.I need some information to do it. I need a
 sketch of the
 firewall showing the position of the motor mount hard
 points, the position
 of the thrust line, the engine off set angles both side
  to
 side and up
 and down as well as the distance from the firewall to the
 prop flange.
 Perhaps a copy of the manufactures fire wall dwg if you
 have it.
  Here is what Scott or Jerry needs to get an accurate
 position of the
 firewall hard points. Five strips of steel sheet metal
  one
 inch wide with holes
 near the ends that represents the distance between those
 hard points.
 Mail or ship those strips to Scott or Jerry so your new
 motor mount
 will fit exactly. If the strips bolt to your
  firewallexactly the
 finished mount will also fit.
  Here is a sketch of the concept.
  Go for a p-port 250 HP. It will help you get off the
  ground
 quicker and is no
 heaver than 200 HP. Unless of course you don't want to
  take
 your engine apart.
  Paul Lamar

  Paul,
 I'll get the drawing of the firewall and dimensionsTail is
  offset, so thrust line is centered.
 My Fuselage is an AviPro Quick Build, so mounting holes
  are
  lined up nicely, thanks to their massive jigs. The
 designer
  did
  all of his designs by paper and pencil. No DWG drawings.
  Interesting part was a friend ran all the numbers though
  his FEA
  analysis and every tube was "just right" for the job
 given
  the
  design and materials used.Amazing as we didn't think
  it was
  possible.
 I've got O/A and TIG welders, in addition to lathe,
  milling
  machine (DRO is fitted), etc. So can build pretty much
 what
  I
  need. I bought the AviPro fuselage to save time.
 Good point on the strapping.I'll confirm
  measurements with the
  DRO on the mill cutting drilling straps.
 Yes, one of Scott's Iron Design tail wheels is also on my
  fuselage. Scott -- Didn't realize you're looking at
 Rotary
  powered Patrol.Elden Yates used a bed mount on his
  13B
  Bearhawk, I think he based it on the RV10 mount the Cozy
  Girls
  are selling, but not positive.The S-beam mount is
  lighter, and
  with a Mill & DRO no problem making up the oil pan.
 I'm looking at the Renesis as a neighbor flying his RV7A
  with
  one is the quietest airplane in the neighborhood. The
  Renesis
  side ports help with that bark, and muffler life.One
  of the
  fellows had a Turbo ports on his RV7, and is still
 working
  on
  getting more than 10 hours of muffler life from it.
 Tom Walter
 Where are you Tom? I'll do the mount and send you the dwg
  with dimensions.
 The trick is make your own mufflers out of .065 thick 321
  SS and you will
  have no problems. Here is a bunch of muffler suggestions
  for 13B's.
 Don't put anything inside the muffler as it will melt and
  come out.
  An exception is a cooled .065 wall center tube. You can
 put
  a center tube through
  a tangential muffler and force cooling air down the tube.
  Makes a good
  cockpit heater or carb heater.
 For non tangential mufflers mounted on the bottom of the
  aircraft
  you can use one or two pipe(s) in and two smaller ones
  coming
  out for lower noise. The smaller the down pipe the
 quieter
  the muffler.
  It is a trade off with back pressure on the engine.
  That applies to tangential muffler mounted under the cowl
  as well.
  The flat parts of a fish mouth must be stiffened with
 sheet
  metal
  angles welded on.
 If you want to cut weight and spend more use .035" thick
  inconel.
 Paul Lamar

 Paul,

 I'm in Cedar Park, TX. Neighborhood airstrip is 40XS.

 Tom Walter

 That sounds like Dennis Haverlah's RV7A. I think he has
 a Hush Power muffler under the cowl.
 How is he doing?  Any problems? Ask him what his top
 speed is?
 I am curious.

 Paul Lamar


Paul,

Correct. Dennis is my neighbor.

He redesigned his 13B Manifold.  There is a speed improvement! Being the
engineer who wants to check and double check his data before saying anything.
There is a photo of his manifold on Bill's photo page.

My wife made the comment that Dennis' RV7 is the quietest on the field,
but he has been hard at work with the muffler.  Renesis helps in that regards.

Bill Eslick posted some photos from last weekend:
http://picasaweb.google.com/wgeslick/AustinRotorfest530

Tom Walter

That is no secret:) That looks like a dynamic chamber manifold to me.
Designed by Mazda to increase the torque at 3000 RPM. Probably works
better than what he had before. Been tried by about half a dozen people
before.

http://www.rotaryeng.net/1984-recent-tech.pdf

Dynamic chambers work but the runners have to be about 12 inches long
to work at 6000 RPM which is not very practical. So far no one has done
it correctly.

I think I need to write an article and put it on the web site so
people don't waste their time trying it over and over again :)


Paul Lamar