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.

Paul Lamar