1/3 Scale 80 HP LeRhone Rotary Aero Engine---A 3 Year
Project
Using
full-scale parts from Murin Antique Aero and WWI Aero Magazine drawings, I drew
in CAD a full-scale metric, and then reduced it to one-third metric for
building. Building the cams, intakes
and rods were really challenging. The two disc cams had to be digitized, as
they are unique. Five lobes, 72 degrees
each, control 720 degree of cycle. One
deg error = 10 deg of cycle error. Also
being a random cam (any cyl) each lobe had to be the same size and shape. The
cam is mounted off center to fit a single drive gear. The 40T int cam and 36T
crank gear (33 deg pitch) have to be very accurate regarding backlash. This is
a very reliable drive but adds an extra sine curve to the motion. Max valve lift is actually on a flank—not a
crest. A single pushrod pulls for
intake and pushes for exhaust. The intake cam due to centrifuge force controls cycle
until exhaust has to open. With only
one push rod adjustment, each valve stem has to be shortened to match
cycle. A dial indicator on each valve
and deg wheel verifies endpoints. Next
obstacle was the famous copper intake pipes. These also were digitized (3D) and
dies were CNC machined for hydro forming.
Prebends were crushed in the die and sized with 6500 psi using a
portapower. The sealing “o” ring groove was spun. The connecting rods are of the crutch
design, which is also unique with LeRhone.
This design is better than a master rod system as all cylinders have
same piston velocity and all forces are on the crank centerline. To obtain a light flying engine, I used
anodized aluminum for the crankcase and jugs—original was all steel. Engine was from bar stock, oil pump and
carburetor had to have castings made—these were wax—investments. Castor oil is used with scale piston pump
and pulser. Block tube carburetor and
ignition cut (coupe) control engine speed.
Note—this engine produces 8.5hp/8.5lb, the full-scale
260lb/80hp=3.25/1.
¼-32
spark plugs are from Napco—Tempe, AZ
C&H
ignition and hall sensor
Fuel—low-test gasoline
Castor oil lube
Prop from Tennessee Propeller 32/28
Dyno-42lb.
thrust at 2700 rpm—18ft/lb. Torque=8.5
hp
Engine
8.5 lb.—prop 1.5 lb.
Bore
35mm Stroke 46.7mm
Thanks
and Acknowledgement
Fred
Murin, Jim & Zona Applebee, Jim Klein, Paul Knapp,
John
Tanzer, Bob Cooper & Peter
Petrushenko
Cory
Stevens and Gerry Nadon—CN Aero Museum in Ottawa
During each engine build, I searched for a suitable stable aircraft. When I saw the Moraine L on the Windsock International, Nov.—Dec. 2003 cover, I fell in love with the
classical elements, high wing for my fuel tanks and side access doors. J. M. Bruce filled in the details with the
Windsock Date file 16. The Page 16
uncovered fuselage was an immense help for scratch building. The half cowl lets the engine, the heart of
the project shine through. The aircraft
is 1/3 sport scale as I used a Clark Y airfoil, ailerons and earlier landing
gear and late fin. Also it has only a
single seat with radio antenna (used) post.
The original used the 80 hp LeRhone and flown by Lt RAJ Warneford was
famous for downing the first Zeppelin.
In flight the rudder was so very effective (proverst jaw) that turns
needed cross control with ailerons. The
flying stab worked very well.
Span
is 12’3 wt-38lbs.
Wing
load 25 oz/sq.ft.
The
aircraft balance perfectly with 8.5 motor and 1.5 lb. prop.
Covering
is Solartex and Nelson clear water base polyurethane
Aluminum
antique airfoil landing gear material from Commander in B. C.
Cowl
is modified Balsa USA. Cowl and all struts were black powder coated.
Vintage
33/28prop.from Tennessee Propellers
9”
wheels--Ried Hobbies
Thanks
and Acknowledgement
Leo
Updyke & Tom Polapink—WWI Aero Magazine
Dave
Millhill & Dan Hayward—Chenango NY R.C. Club
Jim
Quinn, Dick Owens, Bob Pickney—video
Sandy
& Ralph Clobridge---video edit