Bill mentioned a constant speed prop.
 Here is something I saw at Aero.
 Does away with the $1000 Woodward Governor
 and drastically simplifies the PSRU nose.
 No need for a Gov. gear driven mounting pad on the
 nose of the PSRU.

 A small electric pump controlled with a 555 PWM
 could provide oil pressure to a stock constant speed
 hydraulic prop. A high pressure positive displacement
 fuel pump like the Walbro or the Airtex roller vane
 pump could do the trick.

 All you need is a rotating coupling to get the
 oil pressure into the prop. There could be a way
 of modifying Tracy gear box to do this.

 Paul Lamar

 Paul,
 Do you remember the name of the company
 Bill Jepson

 No I don't Bill. They shared a booth and I could not
 find
 any info what so ever.

 Paul Lamar


    I got this off the poster in the back gound. It looks
  like the prop is
    only good to 115HP

    http://www.alisport.com/eu/eng/eliche.htm
    Kevin Bell

    It is the principle that is important and not the actual
  device shown
    at the show.

    The principle will work with Hartzel and McCaully CS
  props.
    Paul Lamar
  -------------------------
  Paul,
  I was under the impression that the governor on a
 McCauley,
  etc. prop was
  actually a pump that was boosting the oil pressure to a
  much higher value
  than engine pressure. I am not sure that a Walbro or
  similiar pump would
  generate enough pressure.

  I could be mistaken.

  Bill Schertz
  KIS Cruiser #4045
  N343BS

  Engine oil pressure can be as low as 30 psi.
  Most fuel pumps can handle double that.
  I don't know about a Walbro but a Airtex (MSD) can put
  out 80 psi at 36 gph.
  You don't need 36 gph for a prop so the max pressure
  may be higher.
  I have one of these things and it is powerful :) I'll
  have to research what
  a CS prop requires.

  Yep you are right. 220 psi.

 http://www.epi-eng.com/propeller_reduction_technology/governor_drive_issues.
  htm

  "Consider the fact that a standard, single-acting
  governor such as found on
  most light singles and twins (Woodward 210xxx series,
  Hartzell and MT prop
  governors) requires less than 3/8 HP to drive at 220 PSI
  output pressure.
  That is 12 pounds-inches of torque at 2000 governor RPM
 and
  less than 9
  pounds-inches of torque at 2700 governor RPM. If the pitch
  diameter of the
  driven gear in the governor drive mechanism is 1.25",
  for example, then
  12 pounds-inches of torque generates 19.2 pounds of
 contact
  force at the
  gear faces."

  3/8 HP is 280 watts or 23 amps at 12 volts for an electric
  motor.
  The oil pump is easy to make from a couple of small spur
  gears.
  Here is a small one I made.

  A small starter motor should work. A regular starter motor
  is 3 HP or 2.2KW
  or 185 amps at 12 volts.

  Electric Starter For Briggs and Stratton
  http://www.nationsautoelectric.com/Smallengine.html
  The geared starters have a smaller, higher RPM motor so
  they are lighter.
  Also more expensive but you need to throw the gear box out
  and use just the
  motor.

  Paul Lamar

  Has this product been considered before?
  http://www.variprop.com/products.html

  C. Smith

  I don't think so but there is not a lot of info on the
  web site.
  It is not clear if it is just ground adjustable or if it
  is a constant speed type prop.

  BTW on second thought the Airtex fuel pump might still
 work
  if it is fed with engine oil pressure. The pump could add
  to engine  oil pressure and get the prop oil pressure up
  around 200 PSI.
  Mazda engine oil pressures are in the region of 100 psi.


  Paul Lamar

 I looked at this [variprop] last year at Sun-n-fun, it is
 fully adjustable
 in the air, constant speed. Little pot mounted on the
 panel.
 I asked about failsafe and it reverts to climb pitch in
 failure
 mode. Seemed like a good product. If you do sun-n-fun this
 year,
 you might look them up.
 C. Smith



I neglected to mention, variprop has a self contained hydraulic
system, independant of engine lubrication system. They also
have the manufacturing rights to the Elippse(tm) propeller
(google it, or find back issue of "Contact!" magazine,
can't remember the issue, and/or look
here: http://www.biplaneaerobatics.com/elippse

C. Smith

The idea here was to use a Hartzel or Mccaully as they are cheap
on the used market and they are metal which is more eff. than
most composite or wood blades.

---------------------------------------------

Something like this would be necessary to adapt Tracy's gear box SAE wood flange
to the smaller SAE hydraulic prop flange and get high oil pressure into the
prop. The seals are standard stretch over Continental or Lycoming
crankshaft seals. I forgot to fillet some of the joints.

Paul Lamar