The new Micro
Joule (MJ) components are perhaps the smallest in micro-flight
technology ever produced for easy plug-n-play usage. The MJ
servos weigh about 0.1oz each and the 0.1oz MJ receiver is
a single conversion narrow band type that automatically detects
the modulation shift for use with Futaba, Hitec, or JR transmitters.
and 2 cell Lithium-compatible Micro Joule ESCs are available
for a wide range of apps.
setups above show a full-house 4-channel system using the
0.1oz, 5amp ESC for 2-cell Lithium operation and a second
3-channel setup for lighter rudder/elevator planes using a
single Lithium cell ESC that can also handle 5amps but weighs
The full-house setup would be great for an indoor aerobatic,
3D, or scale warbird model. The lighter single cell setup
with only two servos would make a great flight pack for a
trainer with rudder/elevator or aileron/elevator controls.
Of course, either setup can use the one-cell or two-cell ESC
option depending upon the plane size and desired motor power.
I have tested both setups on the bench and found no servo
jittering that plagued the first release product. The pre-wired
(and keyed) connectors really made things easier to assemble
and remove. Both ESC versions have a safety arming procedure
that requires the throttle stick to move up to full and back
to off again before powering the motor. All these little added
touches reveal an excellent design strategy by Cirrus!
goal here is to use one of the new improved Cirrus Micro Joule
Flight Packs to convert an inexpensive electric free-flight
plane to R/C.
asked myself, "What is the advantage of using the Cirrus Micro
Joule Flight Pack?", since the cost of these incredibly small
components is greater than other larger flight packs that
The answer is that several things are an advantage with this
new micro-sized flight pack. In the past, micro-flight has
been a complex and specialized area of R/C. Many different
types of knowledge and skill sets were needed to fly a model
that weighed only a few ounces or less. Working with magnetic
actuators was tedious and required considerable experience.
With the Cirrus MJ Flight Pack, I will demonstrate just how
easy it is to convert an inexpensive free-flight model to
R/C. This type of project always gets me excited as it brings
back memories of wishing this were possible when I was just
Hobbico "Classic Cruiser" free-flight plane was chosen for
conversion project will feature the Hobbico FlyZone Classic Cruiser which is under $20 at the local
hobby shop or on-line. The 21.5 inch Cub-like design looks cute
and weighs only 3.0oz RTF stock.
first step was to determine the stock CG and then mark it
on the wing bottom. It was just behind the plastic wing strut.
I cut out
the 2-cell circuit board from the belly of the plane and it
weighed 0.6oz. I then tested the stock motor on a variable DC
supply. At 2.0v it was drawing about 3amps so I figured that
my single Kokam 340mAh cell was a fair match since it can deliver
up to 6amps continuous at about 3.6v.
2-cell circuit board was cut from the belly of the plane.
It weighed 0.6oz.
Typically, these stock free-flight motors are very current
hungry but I wanted to try using it to help simplify the conversion.
Another motor replacement option is discussed later on in
Here is a list of some component weights:
Hobbico Classic Cruiser RTF = 3.0oz
2-cell Charging Board (removed) = 0.6oz
Landing Gear = 0.1oz
Kokam 340mAh pack = 0.4oz
Receiver, Antenna wire, 2 servos, ESC w/wire = 0.4oz
control surfaces were cut out next. Both the elevator and
rudder have lines in the molding for easy tracing with a razor
knife. I used a straight edge and a fresh blade to ensure
a clean cut.
The two elevator halves were then connected with a thin metal
joiner that I epoxied into the "V" area between the halves.
It is best to assemble this on a flat surface. I sanded the
wire first for a better hold and then glued it onto the foam
elevator halves using 5-minute epoxy.
I also sanded a 45 degree angle into both the elevator and
rudder surfaces where they would be taped back onto the plane.
This helps them to swivel properly.
I taped my elevator in place using four pieces of clear cellophane
attaching the elevator assembly, you must first cut out a
small section of foam to allow for a proper swivel up and
down. A 30 degree swing in either direction is plenty since
it is a large elevator.
finished tail looked great! Both control surfaces could easily
swivel 30 degrees in either direction.
mount the rudder, I used a combination of tape and hinge material.
The hinge material on the bottom of the rudder was glued into
pre-cut slots using white craft glue. The hinge material provides
a stronger support for the rudder for adding a steerable tailwheel
(if desired) and for just keeping the rudder in place. Alternatively,
a second piece of tape here would work fine too.
initial position shown here for the servos created a very
choose to mount my MJ receiver and servos in a position that
was easy to install and also provided access for "show and
tell". Most of the local area flying clubs have never seen
this technology before so they are usually loaded with questions
after I fly a 3oz plane outdoors. Note that my initial position
for the servos was not a good choice as it created a very
The receiver and crystal will later be protected with foam
and tape. The servos will need only short control rod runs
to the elevator and rudder. For entry-level simplicity, I
will be using thin metal rods instead of carbon fiber. More experience micro-flight enthusiasts
can use alternate mounting positions, techniques, and materials.
After cutting slots into the foam, the servos are simply held
in place with clear cellophane tape. I glued a balsa piece
inside the fuselage to create a shelf for the receiver to
sit in. It is held in place with double-sided tape. The crystal
will later be bent 90 degrees and held against the fuselage
with clear tape. Another photo will show the receiver sides
protected by foam slices cut for the servo bays.
The stock power system has plenty of built-in down thrust.
I was excited to be able to use the stock power system since
it greatly simplifies the conversion and reduces cost.
Although a direct drive motor uses much more current than
a geared setup, the inefficiency is somewhat negated by the
Kokam 340mAh cell. It will be interesting to see how much
throttle is needed to maintain flight.
I protected the receiver with some foam sides and taped the
bent over crystal with clear tape.
protection is provided by the stock landing gear. All the
components could still be seen on my conversion for showing
it off at local events.
Since the servos were a bit aft, I needed to place my Lithium
cell up front under the nose to balance the plane. I cut a
slot into the foam and the cell just presses in place.
converted Hobbico Classic Cruiser was Ready-To-Fly (RTF) at only
3.3oz with the landing gear. The Cirrus Micro Joule servos
easily controlled the elevator and rudder in both directions.
My initial ground testing showed no sign of jitter or interference.
I can't wait to test fly it!
I wait for a calm day to test fly my converted model, it stores
safely back in the original box with the wing and landing
gear removed. It can stay in my car until needed.
first test flight was a re-learning experience. I had forgotten
that these electric free-flight planes are designed for lift.
By the time I got it under control, I had added two Quarters
(0.4oz) to my nose and drained the battery. The extra weight
equaled my single Kokam cell pack. Upon inspection, I realized that not
only was the stock CG meant to be tail heavy, but the wing
incidence did not seem to match the horizontal stabilizer.
tail-heavy plane needed the Micro Joule components moved
these changes are easily made. I added a 1/32" balsa wedge
to the aft end of my wing saddle so that the angle now matched
the tail. The stock offset is not needed on an R/C model
as you control the climb with the elevator. Note:
After the second set of test flights, it was determined
that the 1/32" balsa wedge was not needed and flew better
It was time to remove the two Quarters and move my components
forward. I easily cut around the Cirrus MJ receiver and
removed the tape from the two servos. Everything was glued
back in place resulting in a much lighter tail section.
extend the existing control rods, I cut them in half and CAed
the wires inside a thin plastic tube. The servo arm and tail
surface alignment was made quickly before the CA had a chance
modified Classic Cruiser simply flew fantastic!
Cirrus MJ Flight Pack performed perfectly without any servo
glitching or radio drop outs. The plane may be a bit hot for
indoor gym flying depending upon your skill set but it flies
great in a small open field.
The newer improved Micro Joule servos have a screwed on arm
that uses a slip-tension to save the control surface when
banged. I simply keep my trim settings at neutral and force
the elevator or rudder back into position by turning the servo
arm by hand. Perhaps it was an unintended"feature".
Classic Cruiser could play up in the clouds or just above
the corn field.
Classic Cruiser could play up in the clouds or just above
the corn field. During no wind conditions, I could throttle
back to about 1/2 or 3/4. Note that I'm now using a direct
drive GWS IPS motor on a single cell with a GWS 5x4.3 prop attached
via a pinion gear. (See the "Motor Alternatives" section)
On my initial set of test flights, I managed to crash the
nose of the plane onto a cement sidewalk which broke the motor
can apart. It didn't seem possible to put back together so
I replaced it with a GWS IPS motor instead.
no wind conditions, I could throttle back to about 1/2 or
direct drive GWS IPS motor provide a lower current alternative.
an easy to follow conversion of the little Classic Cruiser,
the stock motor will work just fine. For a more advanced level
of conversion, replacing the stock motor with a direct drive
GWS IPS motor will provide increased power with a significant
Kokam 340mAh cell can supply 6amps of current and the
plane will fly on partial throttle so either motor will work
but the stock motor draws more current for a similar performance.
It is assumed that the advanced micro-flight enthusiast already
understands the benefits of doing so, and, that my focus is
on a more simple conversion for entry-level enthusiasts.
Cirrus Micro Joule Flight Pack worked perfectly. I saw no
issues with the flight pack when using a single Lithium cell
for power. The available options allow you to use various
components in a 3 or 4 channel micro-flight plane. Converting
an inexpensive electric free-flight plane has not only become
possible but is made much easier using the Micro Joule Flight
main goal for this write-up was to promote some ideas and
inspiration for using the tiny Micro Joule Flight Pack in
your own conversions. Give it a try and you'll have a blast
with the exciting world of micro-flight R/C!
Global Hobby Distributors
Global Hobby Distributors
18480 Bandilier Circle
Fountain Valley, CA 92708
TEL (714) 963-0133