O.S. Engines FS81-a - Manual (Page 6)

10
Tools, accessories, etc. The following items
are necessary for operating the engine.
BEFORE STARTING
The choice of propeller depends on the design
and weight of the aircraft and the type of flying
in which you will be engaged.
Determine the best size and type after
practical experimentation. As a starting point,
refer to the props listed in the accompanying
table. Slightly larger, or even slightly smaller,
Propellers
Type
props than those shown in the table may be
used, but remember that the propeller noise
will increase, due to higher rpm or if a larger-
diameter/lower-pitched prop is used. 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.
Reminder!
Warning:
Make sure that the propeller is well
balanced. An unbalanced propeller and/or
spinner can cause serious vibration which
may weaken parts of the airframe or affect
the safety of the radio-controlled system.
DO NOT forget the WARNINGS and NOTES
on propeller and spinner safety given on
front pages.
Scale
Sport & Aerobatic
Size(DxP)
13x7-9, 14x6-7
11
Since the FS -81-P is intended to
be started with an electric starter,
the addition of a spinner assembly
for centering the starter sleeve is desirable.
Use a heavy-duty, well balanced spinner either
of metal or plastic.
Spinner
FUEL
The FS -81-P should be operated on a methanol based
fuel containing not less than 18% (volumetric) castor oil,
or a top quality synthetic lubricant (or a mixture of both),
plus a small percentage (5-20%) of nitromethane for
improved flexibility and power. (The carburetor is
adjusted a little on the rich side at the factory for a fuel
containing 20% lubricant and 15% nitromethane.) Some
commercial fuels also contain coloring additives as an
aid to fuel level visibility. In some cases, these additives
have indicated slightly negative effects on the
performance.
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.
Reminder!
We would suggest that you use such fuels only if you
are satisfied that they do not adversely affect running
qualities when compared with familiar standard fuels.
When changing to a fuel brand or formula that is
different from the one to which you are accustomed, it is
a wise precaution to temporarily revert to in-flight
running-in procedures, until you are sure that the
engine is running entirely satisfactorily.