Paul, you have inadvertently resolved my "plugs up installation" - it can
be a dead issue with your spur gear PSRU idea, which is an especially good
one.

Only one of these is offered currently, or what I found. If you look at
the "EPI" web address
(http://www.epi-eng.com/gearbox_products/gearbox_products_contents.htm),
wading through a lot of information, you will find that
they offer a spur gear PSRU with a torsion damping connector, but I can't
find
a price which I suspect is high, probably in the neighborhood of $8,000.

Your spur gear idea will move the prop thrust line up more (adjoining
gears) or less (engine driven spur gear with prop driving internal spur
gear),
giving you reverse rotation that you can change back with an idler. EPI
seems
to have a case split along the shaft axis (see photo), I would think it
makes design and installation of internals less complicated, but I have
seldom
seen a axially split case - how strong and reliable would that be? You
mentioned oil passages for constant speed props - you can tap into the case
behind
the hollow prop shaft end.

I too have found engine speed and torque capable gears and bearings hard to
find, meaning I have not yet been able to locate any on the web. You may
have to heat treat the gears yourself at the high end of any rotary HP and
torque range.

But I found a place (http://www.grobinc.com/coldrolled/) that will make
gears for you in long form (like a 24 inch face), kind of like a french
bread
stick loaf, and you cut off "slices" as you need them (see photo).

Hope that helps your brainstorming. I am really enthusiastic about this
PSRU idea of yours. Bernie.


Paul who?

I Paul Lamar do not advocate spur gear PSRU's.

Paul Lamar


Jean, Follow the link above to EPI-ENG,com go to gearboxes on the menu
list, scroll down to the Mark 18 model and have a nice day. Also I
downloaded their propeller technology page which deals with gyroscopic loads
of engine and propeller combinations which you might get something out of. I
havent searched the Grobe gear site a few postings below this, but they
mention stock flanged female splined hubs which may be sized to connectthe
prop to a hollow splined drive shaft and to the 6 ponion planetary on the
other end.So many ideas so little time.

george grimes


George,

Turbine engines are much easier on gears as they have no torsional
pulses. I don't recommend this gear box be hooked to
an intermittent combustion aircraft engine of any kind driving
a prop unless it is tested for many hours. True the rotary is
only 160 to 200 foot pounds but it has a higher frequency
pulse than most piston engines. Not as severe however
as a four cylinder piston engine however.

Various an assorted rotary powered
aircraft have accumulated thousands of flight hours using the Ford
auto transmission parts and a TORSIONAL ISOLATOR of some kind.

The diameter and lengths of the shafts involved are extremely
important. It is an engineering project that will take many
hours of design and testing to insure it is safe.

Paul Lamar


-------------------------------------------------------
The Mark-18, together with the Mark-17 Power Unit Gearbox, was
intended to provide a bolt-in system to replace the notorious
4-cylinder piston engine and drive system in the RotorWay Exec
series of 2-place helicopters with a reliable 150-shp turbine
engine system.

The Mark-18 gearbox is a separate, specially-designed 90°
gearbox for the helicopter main rotor drive. It is NOT adapted
from racecar parts. It bolts directly to the existing main rotor
shaft and to the existing airframe components, and replaces the
lower bearing on the main rotor shaft. It has an optional main
rotor brake.


Thank,s Georges

I read the Mark-18 reduction unit and contact EPI for their
comments on my twin project with rotary engine.

Jean Prudhomme


I'll bet they tell you rotary engines are no good :)

Paul Lamar


Hi George

I look the Mark-18 and i found all major parts they used to built the unit ratio 2.94 to 1

and they have also ratio 2.76 to 1

all parts as follow
I will need some help to design one with a propeller shaft and trust bearing

I will built one and do testing


http://www.justdifferentials.com/index.php?main_page=product_info&cPath=33_104_108&products_id=3049

http://www.justdifferentials.com/index.php?main_page=product_info&cPath=434_438&products_id=1320

http://www.epi-eng.com/gearbox_products/mark-18_gearbox.htm


Jean Prudhomme

I found also part for FORD 9"dia and 3 to 1 ratio but much stronger

Jean Prudhomme

On second thought this is not such a bad idea.
What do those parts weigh Jean?

Do you know of a NC machine shop in Florida that can make
housings for you?

Also what is your budget for shafts and gear boxes?

Paul Lamar