Subject: PSRU fixes
From: rotaryeng
Date: 9/12/2012, 6:42 PM
To: AAAA Put this in the To box


  Barry,

  Before we go too much further, we need a PSRU  that can handle 500+hp.
  We've already had flywheels [flex  plate] disintegrate and my
  input shaft broke the
  lock pin.  I would  consider installing a turbo, but in my opinion, the
  psru is the weakest  link.

  Mark
  P-port 20b

  My last trip to Tracy's we discussed  this. His recommendation  is to use
  an aftermarket aluminum flywheel  and attach the PSRU input to that. His
  latest iteration of the PSRU will  attach to this flywheel easily he says.

  As far as the lock pin, that  would take more thought. Drilling it out
  and installing a larger diameter  pin will increase the shear of the pin
  itself but at a cost to the strength  of the shaft itself.

  Kevin Alderman

  Just install two lock pins  90 degrees to each other.

  We did that on Dave's turbo Reno  racer.

  When I get home I will send a dwg. We have been around and  around on
  this. I am surprised Tracy did not mention it or start doing  it.

  Paul Lamar


  Other than the weight, I take it  there was no problem with the flywheel
  Dave installed?
  Re:  the pins: is it possible that the pins were transfering the power and
  the  pin bores were tight and the spline clearance was allowing the power
  to
  try  to flex the pins?

  Dale Davies

  Dave has reported no  problem so far with the steel flywheel.

  BTW If you can't handle putting  two pins in the sun gear send it to me
 and
  I
  will do
  it. I have done  a couple already,

  Paul Lamar

  Is Dave Leondard racing at Reno  again this year?
  Chris Cosman

  I don't think so.

  Paul  Lamar


  To All,
  While we are addressing PRSU issue's, here is  another one. I'm
  mounting my prop extension and prop; In doing so I have  found
  that my prop tips move about 1". Is this too much back-lash?  Seems
  like I remember hearing that it should be around 1/4". Any  suggestions
  would be appreciated . Thanks!
  Frank Clementi

  Mine  moves about an inch as well. Next time I go to the hangar I will
  measure  it.

  Paul Lamar

  Paul,

  Tracy recently told me the backlash  should be between 3/8 and 5/8".

  Mark

  I'll go out today and see  what mine is.
  Frank, What gear box do you have? 2.17 or 2.85?

  Paul  Lamar


  doesn't the amount it moves depend on the length of the blade?

  What length blades are y'all using?

  Rich

  Yes but it is a minor factor. Most props are 68 to 72 inches in diameter.

  Paul Lamar


 FYI - I'm running a 76" 3-blade prop.

 Mark

 Yes but you have a variable pitch prop and a 350 HP p-port 3 rotor :)
 How much back lash?

 Paul Lamar

 Paul,

Stand by...I'll be checking it on Friday when I'll be at the airport next.

What are your thoughts on the 8 bolts that hold the ring gear to the
housing?  They appear to be 1/4 - 28 bolts.

Mark

Do they hold the bulkhead that holds the ring gear to the housing ?  :)

There are two schools of thought on that. One says you need a bit of slop in the ring
gear and the other says mount it solid.

I don't know if Tracy tried mounting it solid but that would be what I would try
first. The sun gear and planet gears are inherently self aligning. It might take a
sleeve to mount the ring gear solid.

The bolts are not a problem. A 1/4 inch bolt will take a lot of shearing.
The bulkhead made from powered metal is a bit scary however :)

I would also do away with the spline and bolt the planet carrier to the prop shaft.

Paul Lamar


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