Great Planes RimFire 28 User Manual

28mm POWER
SYSTEM

Congratulations, you have just purchased the RimFire 28mm 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 28mm power system are: RimFire
28mm motors, propeller, propeller adapters and brushless speed
controls. This instruction sheet explains how to determine what you
will need and how to assemble each component.

MOTORS

1

Model Stock #

RimFire 300 (28-22 - 1380) GPMG4505
RimFire 370 (28-26 - 1000) GPMG4525
RimFire 400 (28-30 -950) GPMG4560

The RimFire motors are labeled to provide the most information at
a glance. For example: the RimFire 400 (28-30-950) is 28mm in
diameter, 30mm long and has a kV (rpm-per-volt) of 950.

22mm or 26mm or 30mm

28 mm

3mm

5mm

RimFire 300 (28-22-1380) RimFire 370 (28-26-1000)

Input Voltage: 7.4– 11.1V Input Voltage: 7.4– 11.1V
Max Surge Current: 13.5A Max Surge Current: 15A
Max Surge Watts: 150W Max Surge Watts: 165W

RimFire 400 (28-30-950)

Input Voltage: 7.4 –11.1V
Max Surge Current: 20A
Max Surge Watts: 220W

ELECTRONIC SPEED CONTROL (ESC)

2

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 28mm motors.

ElectriFly Silver Series 12
(SS-12) ESC (GPMM1810)
for 12A maximum constant
current draw.

ElectriFly Silver Series 25
(SS-25) ESC (GPMM1820)
for 25A maximum constant
current draw.

The SS-12 comes with 2mm female bullet connectors that plug
directly into the 2mm male connectors installed on the RimFire 28mm
motors, so no soldering is required. The SS-25 comes with 3.5mm
female bullet connectors and requires an adapter (GPMM3122). The
SS-12 comes with a Deans® Micro battery connector that matches the
connectors that are found on most batteries that it will use. The SS-25
comes with a Deans Ultra Plug® battery connector and may require an
adapter (GPMM3126) for some of the batteries.

BATTERIES: NUMBER OF CELLS

3

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 3.7 V, 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 28mm motors will typically use batteries with a capacity of
300 to 1500mAh, with the higher capacity batteries delivering more

Weight

(22mm): 28.5g
(26mm): 40.3g
(30mm): 52.8g

Weight includes:

Motor with collar.

fl ying time but also being heavier. Most of the 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.

No. of

Stock # Voltage Capacity Weight

GPMP0594
GPMP0595
GPMP0704
GPMP0705
GPMG0604
GPMG0605
GPMG0504
GPMG0505
GPMG0510
GPMG0511

4

The RimFire 28mm motor comes with a bolt-on prop adapter and a prop
saver with sleeves to fi t a variety of prop hub sizes. If the RimFire 28mm
motor needs to be mounted behind the fi rewall, the motor requires a 3mm
prop adapter collet type (GPMQ4959), or set screw type (GPMQ4930).

5

There is a wide selection of propellers available for electric use. The RimFire
28mm motors use 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.

GPMQ6630 9x4.5 Slo-Flyer APCQ5010 9x4.7SF Slo-Flyer
GPMQ6655 10x3.5S PowerFlow APCQ5015 10x4.7SF Slo-Flyer
GPMQ6660 10x4.5S PowerFlow APCQ5016 10x3.8SF Slo-Flyer
GPMQ6695 11x4.5S PowerFlow APCQ5020 11x4.7SF Slo-Flyer
APCQ4960 7x4SF Slo-Flyer APCQ5026 12x6SF Slo-Flyer
APCQ5000 8x3.8SF Slo-Flyer APCQ5027 12x3.8SF Slo-Flyer
APCQ5005 9x3.8 Slo-Flyer

6

Now that you have a component for your power system, there are several
different ways to select the rest of the components of your power system.
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 as a 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.

7.4V

11.1V

7.4V

11.1V

7.4V

11.1V

7.4V

11.1V

7.4V

11.1V

300mAh
300mAh
640mAh
640mAh
910mAh

910mAh
1300mAh
1300mAh
1500mAh
1500mAh

oz

0.8

1.1 oz

1.4 oz

2.0 oz

2.1 oz

3.1 oz

2.7 oz

4.0 oz

2.9 oz

4.3 oz

PROPELLER ADAPTERS

GPMQ4930 3mm
Set Screw Type

PROPELLERS

DETERMINE WHAT YOU NEED TO BUILD YOUR POWER SYSTEM

Cells

(24g)
(32g)
(39g)
(56g)
(60g)
(87g)
(77g)

(112g)

(83g)

(121g)

Connector

Adapter

2
3
2
3
2

GPMM3127

3

GPMM3127

2

GPMM3127

3

GPMM3127

2

GPMM3127

3

GPMM3127

GPMQ4959 3mm
Collet Type

RECOMMENDED

SETUP

RimFire 300
RimFire 370
RimFire 400

3S Battery, 8r3.8 SF Prop
3S Battery, 9r4.5 SF Prop
3S Battery, 9r6 SF Prop

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.

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.

ASSEMBLE YOUR POWER SYSTEM

7

Once the required RimFire motor has been determined, it needs to
be installed on the plane. It can be mounted directly to the front of
the fi rewall using the RimFire steel mounting plate included with the
motor, or to the back of the fi rewall using a prop adapter to mount
the prop.

In this manual, you will fi nd the mounting hole template for mounting
the RimFire 28mm motor to the front of or the back of the fi rewall.

Confi guring The Motor

A propeller can be installed onto the RimFire using the included bolt­on prop adapter, 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
bolt-on prop adapter or
the prop saver adapter.
If you choose to use the
bolt-on prop adapter,
secure it to the front of
the motor using the included three 2.5x5mm socket head cap screws
and thread locking compound. A prop washer and prop nut are
included to tighten the propeller onto the bolt-on prop adapter.

If you choose to use the
prop saver adapter, the
motor shaft will need to be
shifted forward inside the
motor. Begin by removing
the c-clip from the front
of the motor shaft. A fi ne,
fl athead screwdriver or
small needle nose pliers
are useful in doing this.
Tip: Crawling around
on your hands and knees looking for a lost c-clip is no fun. Wrap a
sandwich bag around the motor before attempting to remove c-clips.
If the c-clip fl ies off the shaft, it will be contained by the bag. Also, be
sure to wear safety glasses when removing the clips!

Remove the set screw
that locks the motor shaft
to the front endbell.

Loosen the set screw
in the brass collar and
slide it off the back of the
motor shaft.

Remove the c-clip and
washers from the motor
shaft behind the rear
endbell.

Press the motor shaft
forward inside the motor.
Reinstall the washers and
c-clip onto the groove at
the back of the motor
shaft. Rotate the shaft
inside the motor so that
the hole for the set screw
in the front endbell aligns
with the fl at spot on the
shaft. Reinstall the set
screw into the front endbell and tighten it against the shaft with thread
locking compound.

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.

Front Of Firewall Mounting Method

Use the template from the
header card to locate and drill
the mounting holes and the
relief holes for the mounting
plate screws. Attach the
RimFire mounting plate to the
fi rewall using three #4×3/8”
[3×6mm] sheet metal screws
(not included), or a type/
size specifi ed by the airplane
manual.

Behind Firewall Mounting Method

Use the template from the
header card to locate and drill
the holes for the mounting
screws. Attach the RimFire
mounting plate to the fi rewall
using three 3mm machine
screws (not included).

Prop Saver Prop Adapter Installation

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.

Collet Type Prop Adapter Installation

Slide the 3mm prop shaft
over the motor shaft. Next
slide the prop shaft retainer
over the prop shaft. Note that
the hole through the retainer
is tapered. Make sure that the
side with the larger diameter
hole is installed fi rst. Install
the prop, prop washer and
then the prop nut. Tighten the
prop nut against the prop. This will cause the tapered hole in the prop shaft
retainer to squeeze the prop shaft around the output shaft. Carefully pull on
the prop to make sure it is securely attached to the motor shaft.

Set Screw Type Prop Adapter Installation

INSTALL THE BRUSHLESS ESC

8

Mount your ESC in the desired location. Always make sure that the
ESC is positioned so that it gets some cooling air fl owing over it.

Use the instructions included with the ESC to correctly connect
the ESC.

RIMFIRE MOTOR MAINTENANCE

9

RimFire brushless motors require virtually no maintenance. There are
no brushes to wear out and replace. The precision bearings have a
very long service life and should last a very long time. The internal
parts of the motor should not require any cleaning. The only thing that
needs to be checked is to make sure all the screws and set screws
remain tight.

IMPORTANT PRECAUTIONS

10

• Once the battery is connected to the ESC, stay clear of the motor
and prop.

• DO NOT apply an input voltage that exceeds the maximum
specifi cation of each motor.

• DO NOT apply currents to the motor that exceed the maximum
specifi cations of each motor.

• DO NOT allow the input connectors to accidentally touch each other
while power is applied to the motor. Make sure all input connections
are insulated electrically.

• DO NOT allow water or moisture to enter the motor, as it can
cause permanent damage to the motor and possibly short out the
attached ESC.

• DO NOT cut the coated wires from the motor. If you must remove the
bullet connectors, unsolder them.

• Allow the motor to cool after each fl ight.

• The motor shaft of the motor will rotate at very high rpm. DO
NOT attempt to touch the shaft while it is rotating. If setting up
the motor/ESC on the workbench, make sure the motor is securely
attached and that nothing is attached to the motor shaft BEFORE
applying power.

• NEVER attempt to use a damaged motor (having mechanical or
electrical defects).

• ElectriFly carries a complete line of Ammo (in-runner style) and
RimFire (out-runner style) brushless motors, gear drives, motor
mounts, prop adapters and speed controls. For a complete list of
these products, check out our web site at:

www.greatplanes.com www.electrifl y.com

or visit your nearest hobby shop that carries the full line of Great
Planes and ElectriFly products.

Mounting Plate Installation

Although the mount­ing plate comes prein­stalled on the RimFire,
the three 3×4mm ma­chine screws should
be retightened with
threadlocking com­pound. If you plan to
install the motor behind
the firewall, remove the
mounting plate from
the motor.

Optional Mounts Available:

GPMG1201 2-Hole Bar Mount
GPMG1202 4-Hole Cross Mount

RIMFIRE 28mm MOUNTING PATTERN

Slide the 3mm prop adapter
over the motor shaft. Tighten
both of the set screws against
the shaft. Install the prop,
prop washer and then the
prop nut. Tighten the prop
nut against the prop. Carefully
pull on the prop to make sure
it is securely attached to the
motor shaft.

Copyright © 2009 GPMZ0027 V3.0

RimFire 370 Accessory and Spare Parts

GPMQ4625 RimFire Prop Saver (complete set)
GPMM3111 2mm gold plated bullet connectors - female (3)
GPMM3110 2mm gold plated bullet connectors - male (3)
GPMQ4901 Prop Adapter for 28mm motors
GPMG1200 RimFire backplate Motor Mount for 28mm motors
GPMG1201 Bar Mount 28mm RimFire Motors
GPMG1202 Cross Mount 28mm RimFire Motors
GPMG1430 C-clip (10) for 3mm RimFire Motor Shafts
GPMG1409 RimFire 370 Replacement Shaft Kit
GPMG1450 Bearings (2) for RimFire 28-xx-xx motors
GPMG1405 Prop Saver O-rings (5)

RimFire 300 Accessory and Spare Parts

GPMQ4625 RimFire Prop Saver (complete set)
GPMM3111 2mm gold plated bullet connectors - female (3)
GPMM3110 2mm gold plated bullet connectors - male (3)
GPMQ4901 Prop Adapter for 28mm motors
GPMG1200 RimFire backplate Motor Mount for 28mm motors
GPMG1201 Bar Mount 28mm RimFire Motors
GPMG1202 Cross Mount 28mm RimFire Motors
GPMG1430 C-clip (10) for 3mm RimFire Motor Shafts
GPMG1407 RimFire 300 Replacement Shaft Kit
GPMG1450 Bearings (2) for RimFire 28-xx-xx motors
GPMG1405 Prop Saver O-rings (5)

RimFire 400 Accessory and Spare Parts

GPMQ4625 RimFire Prop Saver (complete set)
GPMM3111 2mm gold plated bullet connectors - female (3)
GPMM3110 2mm gold plated bullet connectors - male (3)
GPMQ4901 Prop Adapter for 28mm motors
GPMG1200 RimFire backplate Motor Mount for 28mm motors
GPMG1201 Bar Mount 28mm RimFire Motors
GPMG1202 Cross Mount 28mm RimFire Motors
GPMG1430 C-clip (10) for 3mm RimFire Motor Shafts
GPMG1411 RimFire 400 Replacement Shaft Kit
GPMG1450 Bearings (2) for RimFire 28-xx-xx motors
GPMG1405 Prop Saver O-rings (5)