kevin in denver, Doing a dry sump you can use the current oil pan to
collect the oil and easily scavenge it out of the oil pan with an
aftermarket gerorotor pump such as moroso sells (parker hannifin  internal
parts).This adds firewall forward weight due to the tank  which should be
larger than the pan capacity particularly on the  smaller RX8 pan, a minimum
of two more hoses which present a place  to leak, a third vent hose back to
the engine and weight of the oil  pump and drive.

There is an upside to this
IMHO in  that you would be filtering and then cooling the much hotter   temp
oil returning from rotor cooling and end housings and only this  hotter oil.
Also you will add the pressure pump bypass oil and be  cooling as well as
filtering it on each pass. the stock syster has  the oil fall into the oil
in
the pan mix up with it avaraging the  temperature then pumping it back to
the
engine without any heat  removal.

After the engine pressure pump their is a
relief valve which maintains a set oil presure and flow into the engine.
The
oil which is surplus at the relief valve is directed to the  engine mounted
filter and thru the oil cooler back to the pan.  Therefore we are filtering
less of the oil and cooling with less  delta T at the cooler. These engines
reject A larger percentage of  heat to the oil than a recip because the
hottest parts (the rotors)  are oil cooled.

The  extra 18 pounds of hardware
would be on the accessory end of the engine and firewall area and lessen
the
impact on the firewall forward CG. Add the new one piece front  mount/ PSRU
adapter Paul is developing and get the weight back.As  far as inverted
operation goes, take a  look at the internal  structure of the
center  housing found in photos of housings  sawed in two as  seen in this
newsletter.

Notice  that the oil path  up thru the engine from the eccentric
shaft  is of a similar size to the oil return to the pan. IMHO one could
collect the oil from the filler tube, the top of the accessory housing
with
some tedious drilling and tapping, or just brute force drilling  and epoxy a
steel tube from the top of the rear housing down to the  oil  relief ring
inside the rear oil seal part of the  housing.

The overflow from the engine
pressure  pump relief valve woild be sent (check valve) through this
collection header to a separate scavenge pump so that the pump would  be
lubricated with this oil when flying with the rubber down. I have  not done
this scheeme but plan on doing so, if anyone on the news  letter sees
something  I am missing don't be shy.

george grimes

Keep in mind that I'm doing this in my head as I  am TDY in Washington and
my
garage is in Denver.

I'll have to search  through past graphics on this board to find oil galley
pathways to see  exactly how difficult or easy this may be.Also, this
question was inspired  by my oogling an Aston Martin this weekend.  It has a
dry sump system  allegedly for lateral forces during racing (or because it
impresses wealthy  car buyers...).  Lateral forces are not a factor for
aircraft  engines.  I suppose the 13B factory designed sump would be fine
for most everyday straight and level flying.

But, here's my  thought:  Remove the oil pan completely.Create a header
system for the  oil collection.Use an in-line pump to push the oil into the
oil tank.Mount  the oil tank onto the fire wall (which could act as an
additional oil  cooler/separator).

This shifts weight back toward the CG and exposes  the underside of the
engine to air flow (not a major concern but a possible  added cooling
benefit).With A/N tubing and fittings I don't think leaks are  a factor, but
complexity is indeed added to the factory designed  system.

There is an increase in HP for piston engines using a dry sump,  but is
there
a major benefit for rotaries?I would think a shift of weight,  increased
cooling and increased oil capacity would be the benefits.   Added weight and
added complexity is a liability.  Do they cancel each  other, or is there a
consideration I'm missing?

Kevin in  Denver

The reason piston engine lose HP with oil in the sump is  churning
loses due to the spinning crank. The oil in the sump of a rotary  does
not come near the rotors or the e-shaft.

The oil drain backs in  a rotary are several starting in the front and going
all the way to the  back. You will need some sort of oil pan to collect all
this  oil.

Paul Lamar


Years ago we made the dry sump just a flat plate. No pan. The stock pump
was used for pressure, and a single stage scavenge pump for collecting oil
through a hole in a rotor housing leg. The stock pump was fed through the
flat plate with a flanged fitting in the stock pickup holes. Worked just fine.
 Good steady oil supply to the stock pump. The line from the scavenge pump
goes  through a filter and cooler. The same for the pressure line from the
stock pump.

Then we got a real dry sump pump (Moroso) with 2 scavenge sections. The
stock pump is no longer used. The front scavenge pickup was a half circle cut
into the side of the pressure relief in the front cover. The normal oil out
 fitting becomes the scavenge out for the front of the engine. The rear
scavenge  pick up is a stock oil pressure relief valve gutted and a window cut
into one  side. The window is installed in the down direction and the jamb
nut tightened.  The normal oil-in, banjo fitting in the  rear iron becomes
the rear scavenge out fitting. If there is a fear of debris  damaging the
pump, you can install in-line bug screens.

Some dry sump pumps have the scavenge exit each section, so you have two
scavenge out lines to run through coolers and or filters, and some run one
section into the other inside the pump, and have only one scavenge out  line.

A bit less complexity but either one works fine. Peterson has a selection
of toothed belt pulleys and belts. Also any power transmission shop has all
of  the drive stuff. The later square Peterson pumps are no good.
The pressure section splits open. The older round Petersons are fine.

For inverted use I would use the stock oil filler pipe as the inverted
pickup, using some sort of more secure cap. For long runs right side up, rig a
1/8 Nylon line from the pressure pump, or any line or filter stand to feed
the  inlet side of the inverted scavenge section, through a .015" orifice so
it never  runs dry. One scavenge pickup for up and one for down is fine.
The scavenge  pumps pull a huge amount of air out of the engine and run it
through the oil  tank and then into the breather hose and back into the engine.
So air goes the  wrong way through the breather hose.

Oil pressure is controlled in the pressure pump, not inside the  engine.

You still need the ball type selector valve to pull oil from both top and
bottom of the storage tank.

In the picture, find the dry sump storage tank. Way too big. Later replaced
 with tank made from a hand held fire extinguisher bottle.

Lynn E. Hanover

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