AERONCA Memo M-4
MEMO NO. M-4
Nov. 6, 1935 RES
The AERONCA E-113C ENGINE
The new AERONCA E-113C engine is a two-cylinder horizontally opposed engine
having a piston displacement of 113.5 cu. in. The bore is 4.25 in. and the
stroke 4 in. The compression ratio is 5.4 and the weight of the complete
engine, including the propeller hub, is 121 lb. The engine has a Department
of Commerce rating of 35 HP at 2400 RPM, and is rated by the manufacture at
40 HP at 2500 RPM. This rating is based on a fuel having an anti-knock
rating of 73 octane. This engine now supersedes the well-known AERONCA
E-113B. The AERONCA E-113C engine has been approved by the Department of
Commerce and is now licensed under A.T.C. 71
NEW FEATURES The AERONCA E-113C engine uses the new Federal Mogul cadmium-silver-copper lined, steel backed bearings on the crankpins. These bearings are similar to those used in some of the new automobile engines new on the market. One very desirable feature is the easy replacement of the bearings in service as they are held in the connecting rod by a small notch and can easily be slipped out when the cap is removed on the connecting rod. These bearings are finish-broached to size so that no fitting is necessary to obtain the correct oil clearance. Connecting Rod: The nickel-steel forged connecting rod has been redesigned to take the new Federal-Mogul bearing shells. Crankshaft: The same design of crankshaft is used in this engine as in the previous model and the crankpins are case-hardened for best wear. This crankshaft is finished ground all over and thus has a very high fatigue strength. Pistons, Pins, and Rings: Pistons are made of "Permite" heat-treated aluminum alloy cast in a permanent steel mode, this eliminating sand holes and assuring a good smooth surface inside the piston and also a good balance. The inside of the piston at the upper end is heavily ribbed. The 1/8" compression rings and one 3/16" oil ring are used. Closer clearance is maintained between the piston pin and piston. The full floating piston pin is made of nickel-molybdenum-steel. The pin is retained in the piston by two small snap rings fitted in grooves in the piston on either side. Crankcase Section: The main part of the crankcase section is a single heat- treated aluminum alloy casting which is a streamline shape and contains the oil reservoir of 3 qts. capacity in the lower part. (ed note: See Aeronca engine manual, Part 1 Installation, Section 4 Oil System) The front side of the crankcase is finned to allow the air stream to cool the oil during warm weather. The section can be covered by a metal shield during cold weather to maintain the proper oil temperature. The main crankcase section contains the front ball thrust bearing and the forward main roller bearing of the crankshaft and also the four-lobed camshaft which is mounted on two ball- bearings. The cam follower housings are also in a crankcase and are made of "Permite" heat-treated aluminum allow.
All of the necessary drives are at the rear of the engine. The heat-treated
aluminum allow backplate, which is attached to the rear of the crankcase,
contains the rear main roller bearing of the crankshaft, and also the
accessory drive gear train and oil relief valve. The gear cover attaching
to the backplate is also made of heat-treated aluminum alloy which contains
the tachometer and magneto drives and oil pump.
Cylinder and Head Assemblies: The cylinder heads are of case aluminum alloy,
heat-treated, and contain the rocker arm housing as an integral part. The
valve seats are made from aluminum bronze forgings and are shrunk into the
head. The valve guides are aluminum bronze and are also "shrunk in". The
heads are bolted to the steel cylinders.
The cylinders are machined from chrome-molybdenum heat-treated steel forgings.
The Valves are of the full tulip head type and have been re-designed to use
the new double groove valve spring retainer lock. This change has greatly
increased the strength of the valve at the tip end. The intake and exhaust
valves are interchangeable, which is a desirable feature in this type of
engine. Double valve springs are used on each valve and the two springs
are coiled in opposite directions.
Each rocker are is mounted on two ball bearings which are of the full type
and have shields on one side. The rocker arm bearings and outer push rod
socket are lubricated thru Alemite Zerk fittings on the end of each rocker
arm shaft. The push rods are dural with hardened steel ball ends are are
enclosed in aluminum push rod tubes. The cam followers are of the roller
type and slide in "Permite" aluminum allow housings in the crankcase.
Oiling System: A high pressure oiling system is used on the Aeronca E-113C
engine because of the plain bearings used on the crankpins. The other
bearings in the engine, being either ball or roller, are lubricated by a
splash system.
The oil reservoir is in the bottom of the crankcase and the oil taken from
this reservoir thru a special oil strainer to the oil pump mounted in the
gear cover and from there to the crankpin bearings. This oil line also
goes to the oil relief valve at the top rear of the engine and to the oil
pressure gauge connection. From the oil relief valve, the excess oil is
allowed to flow into the front nose section of the crankcase which is
separated from the cylinders by a wall, and from there into the oil
reservoir. By allowing the oil to flow thru this section of the crankcase,
the front thrust bearing is oiled and heat is taken from the front main
roller bearing and the center wall of the crankcase.
The oil thrown from the crankpin bearings lubricates the cylinder walls and
also the camshaft bearings and then collects in the interior sump of the
engine from where it is removed by the scavenger oil pump to the oil
reservoir.
An oil pressure of 55 to 60 lbs. gauge is normal for this engine. The oil
level in the reservoir can be checked by means of the sight oil gauge on the
top left side of the crankcase. This sight gauge is very handy in long
flights as the exact amount of oil remaining in the engine can be told
at a glance.
(ed note. In reference to 2nd paragraph of this section, the thrust bearing
does not get any lubrication from the overflow of the relief value as stated.
The thrust bearing is lubricated only by a mist of oil that has been thrown
down the tunnel after passing through the front main bearing. The front
main bearing receives its oil from the pressurized connecting rod bearings
that are continually throwing oil around the interior of the crankcase
while the engine is running. In addition, any oil that is added from a can
through the oil refill opening does not flow into the thrust bearing, it
flows only into the engine sump. -Tom)
Breathing Unit: A rather elaborate breathing device is necessary for this
engine in order that the engine will remain clean and no oil will be lost
due to the compression caused by the two pistons traveling inward at the
same time.
The device consists of a small flapper valve which allows the air to flow
only in an outward direction from the interior of the crankcase into the oil
separator. The oil separator is designed to prevent the loss of oil into
the atmosphere while allowing the air to escape. The oil is deflected
downward in the separator and drains from the bottom thru an oil line into
the crankcase proper. The air is allowed to escape upwards thru the
separator and out thru a metal screen. This device produces a slight
vacuum in the crankcase which is desirable in preventing oil leaks at various
joints on the crankcase. This vacuum also draws the oil out of the
separator thru a ball-check valve.
Ignition and Carburation System: A Bosch FF2AR magneto is used with an impulse
coupling for easy starting. The spark is controlled automatically thru a
lever connecting with the throttle on the carburetor, thus eliminating one
control. This automatic spark is very desirable since it reduces the
stresses in the engine, producing a smoother action and allowing a slower
engine speed when idling during the landing of the airplane as the action
is all controlled by the throttle lever.
A Stromberg NAS-2 type aircraft carburetor is used as standard equipment.
An air intake heater is attached to the long "Y" exhaust pipe and furnishes
heat to this carburetor.
HORSE POWER CURVES
Curves correct to std. conditions -- 60°F carburetor air temperature --
29.92"Hg barometer, and .039" Hg water vapor pressure.
A.T.C................ No. 71.
Type................. 2 Cyl. Horizontal opposed, overhead valves, air cooled
Weight Complete ..... 121 lbs. including magneto, carburetor and prop hub.
Rated H. P........... 36 at 2400 R.P.M Department of Commerce rating.
Cylinder Bore........ 4-1/4 inches
Stroke............... 4 inches
Total Displacement... 113.5 cu. in.
Compression Ratio ... 5.4 to 1
Direction of Rotation of Crankshaft - Counter clockwise (facing propeller).
Direction of Rotation of Magneto - Clockwise (facing propeller).
Direction of Rotation of Tachometer Shaft - Clockwise (facing rear of engine)
Magneto Speed ....... 1/2 Crankshaft speed
Camshaft Speed....... 1/2 Crankshaft speed
Tachometer Speed..... 1/2 Crankshaft speed
Oil Pump............. 1/2 Crankshaft speed
Magneto.............. Bosch two spark FF2AR.
Spark Plugs.......... BG4B1 or Champion No. 13 (ed note. The spark plug of
choice today is the Champion C-26. -Tom)
Oil Pressure......... 55-60 lbs at 120-130°F (49-56°C)
Oil Temperature Range Min.-90°F (32°C) before taking off.
Max.-180°F (82°C0 (Hot summer day)
Oil Reservoir....... 3 quarts in crankcase
Oil Recommended......
Saybolt Viscosity Above 80°F. use S.A.E 60, 120 seconds at 210°F
From 80°F to 20°F use S.A.E. 50, 100 seconds at 210°F
Below 20°F use S.A.E. 40-50, 80 sec. at 210°F
Oil Consumption...... Cruising - 1/4 pt. per hour
Fuel Consumption..... Cruising - 3 gal. per hour. Full throttle 3.5 gals/hr
Fuel Recommended..... Aviation gasoline - 73 octane anti-knock rating or
better is approved with tetra-ethyl lead - 1 cc/gal.
preferred. Should be straight run gasoline free from
gum.
Carburetor........... Single. Stromberg NAS-2 aircraft
Valve Tappet Clearance .005 on all valves with cold engine
Valve Adjustment...... In rocker arm
AERONCA AIRCRAFT CORPORATION
Middletown, Ohio
AERONCA "K" and AERONCA E-113 Engine Web Site
http://www.cris.com/~aeronca/