Great Planes PT-E Trainer Electric Kit - GPMA0110 - Manual (Page 41)

Heat: Using multiple battery packs to run the Thrustmas-
ter in successive flights may cause the motor to become
excessively hot Therefore, we recommend a 10-minute
"cool-down" period between flights.
WHEN YOU BLOW A FUSE
The Thrustmaster switch harness uses a 20 amp au-
tomotive-type fuse Replacements may be purchased
through your hobby shop or at most auto supply stores
The fuse is designed to open the electrical circuit when an
overload or short circuit occurs, to protect the other compo-
nents
If the propeller is stalled, such as by running into
long grass or by "nosing over", the motorJtfill draw a very
large electrical current, causing the fuse to "blow" (the
internal fuse wire melts o f f )
Any time you blow a fuse, turn off the switch, discon-
nect the battery, check the condition of the wire, switches
and other components, and replace if any are damaged
Then replace the fuse and check the operation of the sys-
tem.
WARNINGS: Do not use a fuse rated higher than
20 amps, and never operate the system without a
safety fuse, because doing so could easily result in a
fire, causing property damage and personal injury!
HOW TO ACHIEVE THE BEST PERFORMANCE
FROM YOUR ELECTRIC-POWERED MODEL
Whether you are just starting to build your electric-
powered airplane, or have already completed it, you will
benefit from the information that follows
Your objective should be to build your airplane in
such a way that it will fly as it was designed GREAT'
To insure that it does, please read the following comments
and suggestions very carefully, and follow as many of them
as you can
WEIGHT
NOTE In order to get a handle on this subject of
weight, you'll have to be able to accurately weigh your
airplane at various stages of construction A bathroom
scale is definitely not suitable for this' If you do not have
access to a suitable scale, we suggest that you take the
airplane to your local post office and ask them to weigh it
for you.
We know from experience that this airplane,
equipped with a stock Thrustmaster motor, will R 0 G
(takeofffrom a hard-surfaced runway) and fly realistically
with a fully-charged 6-cell battery pack - IF- the total
weight is under 50 ounces Heavier airplanes do not fly as
well At 56 ounces it may not R 0 G , and the climb rate
will be disappointing A PT-Electnc that weighs 50 ounces
or less will probably fly very well unless other factors are
introduced that reduce performance (see " Thrust" and
"Other Factors")
Here are several things you can (and should) do to
keep your airplane as light as possible Keep in mind that
every ounce you cut from the weight will result in a
significant improvement in the way your airplane will
fly.
Lighten the Structure: (If your airplane is overweight)
D 1. Reduce the weight of the wood structure by enlarg-
ing the lightening holes in the fuselage sides (A
Dremel Moto Tool with a sanding drum works great
for this, or use sandpaper wrapped around a dowel).
D 2 Cut out the portion of the stabilizer center section,
as shown on the plan
D 3 "Honeycomb" the 3/16" ply landing gear plate by
drilling several 1/4" diameter holes, as shown on the
plan.
D 4. If the fin and stab structure are hard balsa, you
may sand at least 1/16" off the inside edges of the
Fin, Rudder, Stab, and Elevator Do not remove any
material from the fin and stab trailing edge pieces.
D 5 Before covering, be sure to sand the edges of the
fin, stab, rudder, elevator, wing tips and fuse corners
to a round shape Also sand the fuse sides and bottom
until they are very smooth, with no traces of the
original glue joints.
Use Lighter Equipment:
D 1 It is possible to end up with a 50 ounce airplane
while using "standard-size" servos But your task in
keeping the airplane light will be made much easier
by using "micro" servos For example, you will save
3.6 ounces by changing from Futaba S28 servos to
Futaba S33 servos!
D 2 We strongly urge you to use a 225 mAh radio
battery pack in your airplane, rather than the stan-
dard 500 or 550 mAh pack This will save a couple
more ounces
D 3 You can save a couple of ounces by using the light-
weight Dave Brown wheels If you are concerned
about the non-aerodynamic shape of the wheels, you
can easily sand these foam wheels to whatever shape
you desire This will make them even lighter and
more aerodynamic
D 4 Cover y o u r model with one of the film-type cover-
ings, such as Black Baron Film, Econokote or Super
Monokote, etc Do not use a fabric-type covering
D 5 If you really got carried away with the glue bottle
and your airplane is "hopelessly overweight", con-
sider using an 800 mAh motor battery, rather than
a 1200 mAh pack Although the flight time will be
reduced by a couple of minutes, the weight savings
will result in better performance In addition, if you
switch from a 6-cell 1200 mAh pack to a 7-cell 800
mAh pack it will result in a greatly improved climb
rate (with a reduction in motor run time).
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