O.S. Engines FS-91 User Manual
It is of vital importance, before attempting to operate your engine, to
read the general 'SAFETY INSTRUCTIONS AND WARNINGS' section
on pages 2-4 of this booklet and to strictly adhere to the advice
contained therein.
Also, please study the entire contents of this instruction manual, so as
to familiarize yourself with the controls and other features of the
engine.
Keep these instructions in a safe place so that you may readily refer to
them whenever necessary.
It is suggested that any instructions supplied with the aircraft, radio
control equipment, etc., are accessible for checking at the same time.
SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O.S. ENGINE
Remember that your engine is not a " toy ", but a highly efficient internalcombustion machine whose power is capable of harming you, or others, if it is
misused or abused. As owner, you, alone, are responsible for the safe operation
of your engine, so act with discretion and care at all times.
If at some future date, your O.S. engine is acquired by another person, we would
respectfully request that these instructions are also passed on to its new owner.
The advice which follows is grouped under two headings according to the
degree of damage or danger which might arise through misuse or neglect.
These cover events which might involve serious
WARNINGS
These cover the many other possibilities, generally less
NOTES
obvious sources of danger, but which, under certain
circumstances, may also cause damage or injury.
(in extreme circumstances, even fatal ) injury.
WARNINGS
Never touch, or allow any object to come into contact with, the rotating
propeller and do not crouch over the engine when it is running.
A weakened or loose propeller may disintegrate or be thrown off and, since propeller
tip speeds with powerful engines may exceed 600 feet(180 metres) per second, it will
be understood that such a failure could result in serious injury, (see 'NOTES' section
relating to propeller safety).
Model engine fuel is poisonous. Do not allow it to come into contact with
the eyes or mouth. Always store it in a clearly marked container and
out of the reach of children.
Model engine fuel is also highly flammable. Keep it away from open flame,
excessive heat, sources of sparks, or anything else which might ignite it.
Do not smoke or allow anyone else to smoke, near to it.
Never operate your engine in an enclosed space. Model engines, like automobile
engines, exhaust deadly carbon-monoxide. Run your engine only in an open area.
Model engines generate considerable heat. Do not touch any part of your
engine until it has cooled. Contact with the muffler(silencer), cylinder
head or exhaust header pipe, in particular, may result in a serious burn.
2
NOTES
This engine was designed for model aircraft. Do not attempt to use it for
any other purpose.
Mount the engine in your model securely, following the manufacturers'
recommendations, using appropriate screws and locknuts.
Be sure to use the silencer (muffler) supplied with the engine. Frequent
exposure to an open exhaust may eventually impair your hearing.
Such noise is also likely to cause annoyance to others over a wide area.
Install a top-quality propeller of the diameter and pitch specified for the
engine and aircraft. Locate the propeller on the shaft so that the curved
face of the blades faces forward-i.e. in the direction of flight. Firmly tighten
the propeller nut, using the correct size wrench.
Always check the tightness of the propeller nut and retighten it, if
necessary, before restarting the engine, particularly in the case of fourstroke-cycle engines. A safety locknut assembly is provided. Always use it.
This will prevent the propeller from flying off in the event of a "backfire",
even if it loosens.
If you install a spinner, make sure that it is a precision made product and
that the slots for the propeller blades do not cut into the blade roots and
weaken them.
Discard any propeller which has become split, cracked, nicked or
otherwise rendered unsafe. Never attempt to repair such a propeller:
destroy it. Do not modify a propeller in any way, unless you are highly
experienced in tuning propellers for specialized competition work such as
pylon-racing.
Use an electric starter for this engine. The wearing of safety glasses is also
strongly recommended.
Take care that the glow plug clip or battery leads do not come into contact
with the propeller.
Also check the linkage to the throttle arm. A disconnected linkage could
also foul the propeller.
3
NOTES
Adjust the throttle linkage so that the engine stops when the throttle stick
and trim lever on the transmitter are fully retarded. Alternatively, the
engine may be stopped by cutting off the fuel supply. Never try to stop the
engine physically.
Take care that loose clothing (ties, shirt sleeves, scarves, etc.) do not come
into contact with the propeller.
Do not carry loose objects (such as pencils, screwdrivers, etc.) in a shirt
pocket from where they could fall through the propeller arc.
Do not start your engine in an area containing loose gravel or sand.
The propeller may throw such material in your face and eyes and cause
injury.
For their safety, keep all onlookers (especially small children) well back (at
least 20 feet or 6 meters) when preparing your model for flight. If you have
to carry the model to the take-off point with the engine running, be
especially cautious. Keep the propeller pointed away from you and walk
well clear of spectators.
Warning! Immediately after a glowplug-ignition engine has been run and is
still warm, conditions sometimes exist whereby it is just possible for the
engine to abruptly restart if the propeller is casually flipped over
compression WITHOUT the glowplug battery being reconnected.
Remember this if you wish to avoid the risk of a painfully rapped knuckle!
4
INTRODUCTION
This is the FS-91S -FI (fuel injection) engine equipped with a
revolutionary fuel supply system that was jointly developed by Futaba, a
manufacturer of Radio control equipment, and O.S. Engines, a
manufacturer of model engines.
This system detects engine speed with a sensor based on throttle
signals transmitted from a transmitter. It then determines the fuel
injection volume based on the required amount of fuel to be supplied for
that engine speed as calculated by an electronic control unit (EC-2<FS91S -FI>) referred to as the "EC-2", after which fuel is injected into the
engine from an injector. In addition, adjustments can also be made using
dial on the transmitter. The result is an engine for sport models that
features excellent engine speed linearity relative to throttle operation
under all types of flight conditions.
FEATURES
Supplies the Proper Amount of Fuel at all Times
Easier starting
Greater stability during idling
Excellent linearity and response relative to stick operation.
Simple Adjustment Using Dials on the Transmitter
Air-fuel mixture at medium and high speeds can be safety and easily adjusted
from the transmitter.
Adjustments can be made while on the ground and during flight.
Stable Supply of Fuel at all Times
Pressurized fuel is controlled at a constant pressure with respect to all types of
movement during flight allowing stable engine performance at all times.
Light Weight and Easy Installation
The sensor and injector mounted on the engine are both compact and
lightweight, while the electronic control unit (EC-2) is also lightweight, enabling
various connections to be made easily the same as plugging in a servo.
5
BASIC ENGINE PARTS
Accessories
EC-2 Assembly
Y harness
Duble-sided sponge-
backed cushioning tape
Check Valve
Fuel Filter
Driver to push Limit
Setting Switch
Glow plug TYPE F
F-4020 Silencer
Glow plug
TYPE F
Temperature
Sensor
Rocker Cover
Cylinder Head
Propeller Washer
Lock Nut
Propeller Nut
Injector
Air Valve 60T
RPM Sensor
Electronic Control Unit<EC-2>
Injector
Crankcase
Beam Mount
Drive Hub
Never attempt to disassemble the injector.
Injector
The injector consists of a solenoid valve with built-in regulator. It controls pressurized fuel at a constant
pressure and accurately injects fuel based on signals from the electronic control unit (EC-2).
Temperature Sensor
It may not be able to be reassembled.
This measures the temperature of the engine exhaust unit.
RPM Sensor
The RPM sensor is provided with a power generating sensor. When the crankshaft passes in front
of the sensor, the signal that is generated is transmitted to the electronic control unit (EC-2).
Engine rpm are then detocted based on that signal which is then used to determine the timing at
which fuel is injected.
Electronic Control Unit<EC-2>
The EC-2 transmits fuel injection signals to the injector to ensure the proper amount of fuel
injection based on basic fuel injection data that has been previously entered and constantly
changes with position of throttle stick.
This one-way valve's function is to pressurize the fuel tank by crankcase
Check Valve
Fuel Filter
Y harness
pressure and prevent fuel from returning to the engine crankcase.
This fine mesh filter prevents foreigh matter from the fuel tank from plugging
the small injector valve.
This cord is used to connect the receiver (throttle channel), throttle servo and EC-2.
(abbreviated as simply EC-2)
6
CONNECTING WITH THE EC-2
Connect the receiver and servo-related components (rudder section) in the same manner as in the past.
(8) Integrated Buzzer
(3) Injector output terminal
(2) Injection trim input terminal
(AUX:TRIM)
(1) Injection time input terminal
(CH3:THRO)
(6) Limit Setting Switch(LIMIT)
Two extension cords (sold separately) of a length corresponding to the airframe are required for
connecting (1) and (2).
(7) L.E.D.
(1) Injection Time Input Terminal<Black> (CH3:THRO)
Connect the y harness provided with the CH3 THRO input terminal to throttle channel of the
receiver (throttle: CH3), connect the wiring connector from the throttle servo to one of the doubleopening connectors on the opposite side, and connect the other double-opening connector to
CH3:THRO of EC-2. (Use the separately sold extension cord if the wiring cords are too short.)
(INJECTOR)
Temperature sensor input
(4)
terminal (Temp)
(5) RPM sensor input terminal
(r.p.m.)
(2) Injection Trim Input Terminal<Red> (AUX:TRIM)
Connect a spare channel for dial use of the receiver (e.g. channel 7) to the AUX:TRIM terminal.
(Use the separately sold extension cord if the wiring cords are too short.)
(3) Injector Output Terminal
Connect the injector connector to the injector output terminal. Protect the lead wire with a heatresistant tube,etc. if it makes contact with the engine mount.
(4) Temperature Sensor Input Terminal
Connect the temperature sensor connector to the temperature sensor input terminal.
(5) Rotation Sensor Input Terminal
(6) Limit Setting Switch(LIMIT)
Connect the rotation sensor connector to the rpm input terminal.
Push with driver supplied when setting limit.
7
(7) L.E.D.(Display of green and red)
It flashes or changes color when setting and cheking limit, and adjusting injection trim. It flashes with the color of
the injection trim when the engine is running.
LED Display
Transmitter Operation
Turn the dial right to reduce injection volume.
When the engine
is not running
When the engine
is running
Turning direction of dial shows the standard setting direction.
Dial position shows plus (green - rich) or minus (red - lean) from the zero position (basic injection volume.)
Turn the dial left to increde injection volume.
Limit position
Turn the dial right to reduce injection volume.
Turn the dial left to increde injection volume.
Red lights
Green lights
Flashes
(color depends or the dial position)
Red flashes
Green flashes
LED Status
(8) Integrated Buzzer
Buzzer sounds when setting Limit, dial is set nnetral a error happens.
Buzzer notes and status
Notes
Nil
One note (Pi)
Two successive notes (PiPi)
Repeated one note (Pi...Pi...)
Repeated two successive notes (PiPi...PiPi...)
Repeated three successive notes (PiPiPi...PiPiPi...)
mark shows alarm for error.
Fig.1
Temperature Sensor
Injector
Status
Normal
Limit at Low is set
Dial neutral
Limit at High is set
Temperature Sensor is disconnected
Error on setting Limit
Battery voltage falls down (below 3.8v)
Transmitter
F S
SERIES
MADE IN JAPAN
Rotation Sensor
AUX
Throttle Channel
Throttle Servo
8
EC-2
Branched Cord
Receiver
CH3
受信機
AUX＊
Spare Channel
Injection trim adjustment
corresponds to needle-valve adjustment of conventional carburetor)
Injection trim can be adjusted independently
for two area as shown in the graph.
Intermediate slow and full high are adjusted
with the injection trim adjustment dial (spare
channel dial) on the transmitter.
Intermediate slow
basic injection
volume
Fuel injection volume
234567
1
Lo
(Throttle stick position)
Mi
Fig.2
Full high
9
8
Hi
LIST OF FS-91S -FI USAGE CONDITIONS
Part
Silencer
Glow plug
Propeller
Manufacturer
O.S.
O.S.
Commercially
available
high-quality
product
General references:
13x9 (Basic propeller)
13x10-11, 12.5x9
12x13
14x10
Name
F-4020
TYPE F
Remarks
Maximun speed should be
between 8,000 and 9,000 rpm.
Fuel
Transmitter
Aircraft
The contents of the user's manual are based on those products indicated with an asterisk ( ).
Commercially
available
high-quality
product
FUTABA
FUTABA
FUTABA
JR
JR
JR
JR
SANWA
10-25% nitromethane
15-20% oil
1024ZA T9Z
FF8A
FF9
PCM10S
PCM10X
X3810
X378
STYLUS
RD6000 Super
Sport
Adjustment may vary slightly according to
the amounts of nitromethane and oil.
Use a fuel containing as low nitromethane
as possible within the percentage shown
left. Too much oil may cause malfunction.
Spare channel dial (used at 100% by
canceling mixing and expo, etc. when
used alone.
In case of FUTABA, set with spare
channel NORM direcion.
In case of other marks, it is necessary to
change setting it the direction is reverse.
Only Z connectors can be used
(check whether polarity matches).
Wingspan 1.3-1.8m Weight 3-4kg
9
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