Is there any reason why the particular gear ratio between the rotor and the
  output shaft (not sure if this is the proper term) was chosen?  Would there
  be a way to modify this so that the PSRU was essentially integrated into
  the
  motor?  So, for example, so that 4 turns of the rotor were necessary for
  one
  turn of the shaft instead of 2?

  Just a thought, but might save alot of weight and one of the major risk
  factors of auto conversions.

  Thanks,
  Brannon

  I am not sure what you mean by "integrated".
  Can you come up with a sketch?

  Paul Lamar


  Brannon,   The PSRU ratio ideally is the engine RPM at max power for take
  off devided by the RPM where the prop tips are going supersonic. The next
  factor is that in our case we don't particularly want the added weight of
  offsetting the thrust line above the E-shaft center. The planetary gear
  arrangement puts the output shaft directly in line with the e_shaft with
 the
  added benefit of driving through 6 planet gears for a minimum of 6 teeth
  transmitting the power rather than one tooth on a gear to gear drive. There
  is also a lot  of cumulative line contact on the gears with the planetary,
  therefore a relatively small gearset can be used. The gearset of choice is
  from Real World Solutions designed by Tracy Crook. This PSRU uses
  a superduty ford diesel (E40D) low range planetary which happens to be 2.85
  ratio  when the ring gear is held and the planetary drives the prop Holding
  the ring gear also turns the prop the same direction as the engine rather
  than reversing the rotation allowing a larger selection of props to use..
  Ideally  we could use more gearing in the range of 3.20 to 1   but to use
  mass produced gearsets we have to choose something commonly available.  In
  my case (6 Rotor) I need a larger gearbox for 700 HP and after looking at
  photographs of planetary gearsets for sale on E-bay I chose the 4 wheel
  drive transfer case planetary from the same superduty Ford F350
  transmission. The ratio is 2.64 to one. More gear would be better, however,
  this gearset needs no machining off of extra parts  and is well supported
  with bearings. It is also 4 pounds heavier than the E40D but I  can't
  compare the weight of something not strong enough with something that is
  overkill. This planetary is only used when the 4-wheel drive is in low lock
  so even used there are very few hours of operation on the parts. I bought
 my
  set for $45 and it looks like new. I entered all the Ford parts in Rhino4
  last weekend and am designing the housing next weekend. I still don't have
  the shaft mounted oil pump that fits around the input shaft in the truck
  which I will use for pressure lubrication after running the oil through a
  cooler. This will allow useing gear lube in the PSRU rather than engine
 oil.
  I well attempt to attach a JPEG image of the Rhino4 drawing showing the
 Ford
  parts and the thin wall prop shaft designed to use this gearset. All drive
  is thru splines including one that has to be cut near the end of the
  propshaft The rest of the splines are used as is..The JPEG named geartrane
  shows the Ford parts which are used as they come out of the truck. The JPEG
  named PSRU componets includes the propshaft as well as the parts assembled
  for use. In both images there are two lineups of the parts showing the view
  from both ends.


  george grimes


George,

I wonder what propeller you plan to use.  Avia?  In order to get 700hp
from a 6 rotor, it seems that you'll need to run the engine at upwards
of 6000 rpm (naturally aspirated).  That will make your prop RPM
around 2300+.  An engine of similar horsepower is the PW R1340.  Most
of those are direct drive - like mounted on the old T6 Texan (SNJ),
and are generally rated at 2200 RPM.  In that application, the two
bladed prop is terribly noisy at takeoff (full) RPM, certainly losing
some efficiency.  I understand that they are 108" diameter.  A 3
bladed prop of smaller diameter will help..  Being able to turn the
prop slower would be even better.


Regards,

Matt-

I would not put too much credence to a six rotor. The output shaft on
the last rotor is not getting any larger. My guess is 5 rotors is pushing it.
Emon Hurley built one years ago.

Paul Lamar