22
fi ngertips. As long as the model balances anywhere within
the specifi ed range it is acceptable (but less-experienced
pilots should perform fi rst fl ights with the PT-19 balanced in
the middle or forward half of the range—slightly nose heavy).
❏
3. If the PT-19 doesn’t balance where specifi ed, move the
receiver battery or motor battery or add stick-on lead ballast
to the nose or tail to achieve the correct C.G.
❏
4. If you’ve made any adjustments by adding ballast or
moving components, check the C.G. again before fl ying.
Balance the Model Laterally
❏
1. Lift the PT-19 several times by the propeller shaft and
the tail to see if one wing drops.
❏
2. If one wing drops consistently, add weight to the
opposite tip by sticking it to the outside or strategically
concealing it inside the balsa tip.
An airplane that has
been laterally balanced will track better in fl ight and
maintain its heading better during maneuvers when the
plane is climbing.
PREFLIGHT
Engine/Motor Safety Precautions
Failure to follow these safety precautions may result
in severe injury to yourself and others.
●
Keep all engine fuel in a safe place, away from high heat,
sparks or fl ames, as fuel is very fl ammable. Do not smoke
near the engine or fuel; and remember that engine exhaust
gives off a great deal of deadly carbon monoxide. Therefore
do not run the engine in a closed room or garage
.
●
Get help from an experienced pilot when learning to
operate engines.
●
Use safety glasses when starting or running engines.
●
Do not run the engine in an area of loose gravel or sand;
the propeller may throw such material in your face or eyes.
●
Keep your face and body as well as all spectators away
from the plane of rotation of the propeller as you start and
run the engine.
●
Keep these items away from the prop: loose clothing, shirt
sleeves, ties, scarfs, long hair or loose objects such as
pencils or screwdrivers that may fall out of shirt or jacket
pockets into the prop.
●
Use a “chicken stick” or electric starter to start the engine.
Do not use your fi ngers to fl ip the propeller. Make certain
the glow plug clip or connector is secure so that it will not
pop off or otherwise get into the running propeller.
●
Make all engine adjustments from behind the rotating
propeller.
●
The engine gets hot! Do not touch it during or right after
operation. Make sure fuel lines are in good condition so
fuel will not leak onto a hot engine, causing a fi re.
●
To stop a glow engine, cut off the fuel supply by closing
off the fuel line or following the engine manufacturer’s
recommendations. Do not use hands, fi ngers or any other
body part to try to stop the engine. To stop a gasoline
powered engine an on/off switch should be connected to
the engine coil. Do not throw anything into the propeller
of a running engine.
WARNING:
For brushless electric motors, never have the
motor battery connected to the ESC without the transmitter
turned on – after each fl ight (or any time after running the
motor)
always
disconnect the battery
before
turning off
the transmitter. And when ready to fl y (or whenever running
the motor for any reason), always turn on the transmitter
fi rst before connecting the motor battery.
Also make certain your
failsafe
is programmed correctly
so in the event the receiver ever loses signal (or, if you
inadvertently turn off the transmitter before disconnecting
the battery or vice-versa) the motor will not turn. Follow
the instructions that came with your radio control system
to check and set the failsafe.
The recommended RimFire .32 is rated for 50A constant
current and 80A surge current, so it is desirable to load
(prop) the motor to operate within that range. The closer to
50A the longer you can fl y full-throttle and the closer to 80A
the less you can fl y full-throttle until the motor gets too hot.
To begin, an APC 13 x 8E (on a 4S LiPo) draws about 58A
static and momentary, maximum peaks of about 50–55A
in the air, but averages a little less than 20A with “normal”
throttle use. This is a suitable propeller choice and fl ies the
PT-19 well—it can be zoomed around boreing holes in the sky,
or cruise at lower throttle settings for more scale-appearing
fl ight and extended air time.
We’ve also fl own the PT-19 with a 13 x 10E on 4S which
peps it up noticeably. Then, the static current rises to about
68A with momentary, maximum in-fl ight peaks up to around
70A and averages around 50A with normal throttle use. The
13 x 10E is another suitable propeller, but
prudent throttle
management
must be used so as not to overheat the motor
and if necessary, it may be a good idea to allow the motor
to cool between fl ights.
With every propeller, fl ight time depends greatly on how you
use the throttle. Average current draw can be as low as 13
Amps up to as high as 50 Amps if you’re REALLY hard on
the throttle.
In any case, use a fl ight timer initially set to a conservative
time (4 minutes for example). When the timer sounds, land.
Resting (unloaded) voltage should not be below 3.75V/cell