Great Planes RimFire 250 Power System - Manual

Because every motor has a maximum current it can take based on its
design and cooling ability, the maximum size of propeller that can be
used with each motor can be determined. Too large of a propeller and
the motor will spin at a much lower rpm than its rated kV, causing it to
draw a lot of current and overheat. If the propeller/fan is too small, it
will require little effort (current) to turn the prop at the rated kV.
Ideally the motor should be matched with a propeller that causes the
motor to draw 80-100% of its rated maximum constant current. Once
a power system is set up, it can be fi ne-tuned by adjusting the propeller
size and measuring the amount of current the motor is drawing.
Please note that the kV of a motor does not change with voltage, but
if a higher voltage is applied to the motor, it will try to spin the same
propeller at a higher rpm. This will cause the motor to draw more
current and possibly exceed the maximum rated current of the motor.
So, if a battery with lower voltage is replaced with one with a higher
voltage, it is recommended that a smaller propeller be used to keep
the current in check. If a higher voltage battery is replaced by a lower
voltage battery, the size of the propeller can be increased to keep the
motor at its rated current.
Another possibility to fi ne tune the power system’s performance is to use
another motor with higher kV to increase the current or a lower kV to lower
the current.
7
ASSEMBLE YOUR POWER SYSTEM
The RimFire 250 can be mounted directly to the front of the fi rewall or
behind the fi rewall using the optional reverse shaft (not included).
At the back of this manual, you will fi nd the mounting hole template
for mounting the RimFire 250 motor to the front or the back of the
fi rewall.
Installing The Propeller
A propeller can be installed onto the RimFire using the included prop
saver adapter or a collet-type prop adapter (not included).
If you are installing the
motor onto the front of
the fi
rewall (common
installation), the propeller
can be installed onto
the prop saver adapter,
requiring only a rubber
O-ring to secure the prop
in place.
The included prop saver
adapter can be installed
with either end facing
forward. One end has a
diameter of 5mm and the
other end has a diameter
of 6mm. For other prop
hub sizes, 7mm and
7.85mm adapter sleeves
are also included to fi t
over the 5mm diameter prop saver end. Orient the prop saver adapter
in the direction that best suits your propeller and install it onto the
front of the motor shaft and tighten the screws against the fl at spots
on the shaft.
Install the cowl if the
plane comes with one.
Install the prop on the
prop saver and secure
it with a rubber O-ring
looped over both of the
machine screws. Check
the O-ring for wear
before each fl ight. If the
O-ring shows any cracks,
replace immediately.
Front Of Firewall Mounting Method
Use the template from
this manual to locate
and drill the mount-
ing holes and the relief
hole for the end of the
motor shaft. Attach the
RimFire mounting plate
to the fi
rewall using
three #2x3/8” [2x10mm]
sheet metal screws (not
included), or a type/size
specifi ed by the airplane manual.
4
PROPELLER ADAPTERS
The RimFire 250 motor comes with a prop saver with sleeves to fi t
a variety of prop hub sizes. If your application will use a spinner, the
motor will require a 3mm prop adapter collet type (GPMQ4959), or set
screw type (GPMQ4930).
GPMQ4930 3mm
Set Screw Type GPMQ4959 3mm
Collet Type
5
PROPELLERS
There is a wide selection of propellers available for electric use. The RimFire
250 motor uses high performance slow fl y electric props. The larger the
propeller used, the more current your motor will draw. The smaller the
propeller, the less current the motor will draw.
Shown are a few of the recommended electric props. Due to the large
range of propellers and the constant addition of new sizes, visit our web
sites at www.electrifl y.com and www.greatplanes.com for the most up-
to-date listing of electric type props.
APCQ4960 7x4SF Slo-Flyer GWSQ2008 7x 3.5 Propeller
APCQ4961 7x5SF Slo-Flyer GWSQ2009 8x4 Propeller
APCQ5000 8x3.8SF Slo-Flyer GWSQ2010 9x5 Propeller
Stock #
GPMP0594
GPMP0595
GPMP0700
GPMP0701
GPMP0704
GPMP0705
Voltage
7.4V
11.1V
7.4V
11.1V
7.4V
11.1V
Capacity
300mAh
300mAh
300mAh
300mAh
640mAh
640mAh
No. of Cells
2
3
2
3
2
3
Weight
oz
1.1 oz
0.7 oz
1.0 oz
1.4 oz
2.0 oz
(24g)
(32g)
(20g)
(28g)
(39g)
(56g) 0.8
6
DETERMINE WHAT YOU NEED to BUILD YOUR POWER SYSTEM
Now that you have one component for your power system, there are
several different ways to select the rest. In time, experience will help you
to determine what works best for you, but an easy way to determine what
you need now is the following.
Procedure #1: If you know the size of the propeller you want to turn and
the rpm, then:
❏ 1. Find the combination that delivers the closest performance to what
you want, (refer to the ElectriFly web site for typical combinations) or
refer to the airplane manufacturer’s recommendations.
❏
2. Note the recommended battery voltage.
❏ 3. Determine the battery capacity needed based on the current draw of
your system and your desired fl ight time.
❏
4. Determine the ESC you need based on the system current draw. See
the ESC section.
Procedure #2: If you know the approximate weight of your airplane,
including the motor and battery, and the performance you want from it,
answer the questions below to determine the correct power system for
your plane. You may need to make more than one calculation using different
motors and battery combinations. See the battery section for some of the
battery weights for the suggested batteries.
❏
1. Perform the following calculation to determine the wattage required:
• If you expect trainer-like performance then multiply 75 x Airplane
Weight (lbs)
• If you expect aerobatic or high speed-like performance then multiply
100 x Airplane Weight (lbs)
• If you expect 3D or extreme performance multiply 150 x Airplane
Weight (lbs)
❏ 2. The number you get is the minimum wattage you will need for your
plane to perform as you wish. Watts = current (A) × voltage (V). Using
suggested power system combinations for reference, determine what
combination gives you the performance you want based on wattage
and maximum propeller size that will fi t on the plane.
❏ 3. Note the recommended battery voltage.
❏
4. Determine the battery capacity needed based on the current draw of
your system and your desired fl ight time.
❏ 5. Determine the ESC you need based on the system current draw.
In addition to these two procedures, you can also visit the Great Planes
ElectriFly web site for descriptions of the power systems recommended for
our line of electric and glow airplanes as well as more detailed explanation
on the subject.
Understanding Motors
kV (rpm/volt): This is a number that gets thrown around quite a bit when
talking electrics and it is important to know what it is. kV is the number of
rpm a motor will spin per each volt applied (rpm/volt) under no load.
This means that basically a motor that has a kV of 1000 when connected
to a 12V battery will try to spin at 12,000rpm (1000x12) under no load.
Likewise a 3500kV motor will try to spin at 42,000rpm (3500x12) under
no load.
When a propeller is attached to the motor, the motor will try to spin the
prop at the rated kV. Depending on the diameter and pitch of the propeller
(the larger the diameter or higher the pitch, the harder it is to spin), the
motor’s current draw can be increased or decreased. There are meters
available from your hobby dealer that measure current and voltage.
Congratulations, you have just purchased the RimFire 250 power
system components. All the components are sold separately to allow
you to customize your power system to your airplane. The components
needed to assemble your RimFire 250 power system are: RimFire 250
motor, propeller, propeller adapters and brushless speed controls.
This instruction sheet explains how to determine what you will need
and how to assemble each component.
1
MOTOR
Model Stock #
RimFire 250 (28-13 - 1750) GPMG4502
The RimFire motors are labeled to provide the most information at
a glance. For example: the RimFire 250 (28-13-1750) is 28mm in
diameter, 13mm long and has a kV (rpm-per-volt) of 1750 rpm.
28 mm
Weight
20.5g
13 mm
Weight includes: Motor w/prop adapter.
2
ELECTRONIC SPEED CONTROL (ESC)
An ESC is basically the device that controls your motor through your
radio system. Never run any RimFire motors with a brushed ESC.
It will not work and you may damage both the motor and the ESC.
Always use a brushless ESC. ElectriFly offers Brushless ESCs that will
work with the RimFire 250 motor.
ElectriFly Silver Series 8
(SS-8) ESC (GPMM1800)
for 8A maximum constant
current draw.
ElectriFly Silver Series 12
(SS-12) ESC (GPMM1810)
for 12A maximum constant
current draw.
The SS-8 and SS-12 come with 2mm female bullet connectors that
plug directly into the 2mm male connectors installed on the RimFire
250 motor, so no soldering is required. The SS-8 and SS-12 also come
with a Deans
® Micro battery connector that matches the connectors
that are found on most batteries that it will use.
3
BATTERIES: NUMBER OF CELLS
Cells can be connected in series or in parallel. Usually batteries are
labeled by their number of cells, such as a 3-cell LiPo. This means the
cells are connected in SERIES (S). Arranging batteries in series gives
you more power (higher voltage).
• Each LiPo battery has 3.7V, so a 3-cell
LiPo battery has 3.7 x 3 = 11.1V
If a battery is arranged in PARALLEL it might be labeled as (P). Arranging
the batteries in parallel will give you more duration (more capacity).
ElectriFly offers a full line of LiPo batteries. Airplanes that use the
RimFire 250 motor will typically use batteries with a capacity of 300 to
640mAh, with the higher capacity batteries delivering more fl ying time
but also being heavier. The suggested batteries have connectors that
fi t the recommended ESC.
Due to the constantly changing battery technology, check out the
ElectriFly web site at www.electrifl y.com for the most up-to-date
listing of the ElectriFly battery line.
250 POWER
SYSTEM