απο το φυλλαδιο οδηγιών του κ/τ...
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
Sport 12x7-8, 13x6-7props than those shown in the table may be
used, but remember that speed the propeller
noise will increase if blade tip is raised, 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.
και το manual...
http://manuals.hobbico.com/osm/55ax-manual.pdf