RCU Review: Cirrus Micro Joule System

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    Contributed by: Greg Covey | Published: September 2004 | Views: 27729 | email icon Email this Article | PDFpdf icon
    Untitled Document

    Review By: Greg Covey

    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.

    1 and 2 cell Lithium-compatible Micro Joule ESCs are available for a wide range of apps.

    The 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 only 0.07oz.

    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!

    My 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.

    I 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 weigh more.

    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 a kid.

    The Hobbico "Classic Cruiser" free-flight plane was chosen for the conversion.

    My 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.

    The 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.

    The 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 the review.

    Here is a list of some component weights:
    Stock Hobbico Classic Cruiser RTF = 3.0oz
    Stock 2-cell Charging Board (removed) = 0.6oz
    Stock Landing Gear = 0.1oz
    1-cell Kokam 340mAh pack = 0.4oz
    MJ Receiver, Antenna wire, 2 servos, ESC w/wire = 0.4oz

    The 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 tape.

    Before 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.

    My finished tail looked great! Both control surfaces could easily swivel 30 degrees in either direction.

    To 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.

    The initial position shown here for the servos created a very tail-heavy plane.

    I 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 tail-heavy plane.

    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.

    Additional 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.

    My 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!

    As 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.

    My 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.

    The tail-heavy plane needed the Micro Joule components moved forward.

    Fortunately, 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 without it.

    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.

    To 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 to set.

    My modified Classic Cruiser simply flew fantastic!

    The 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".

    My Classic Cruiser could play up in the clouds or just above the corn field.

    My 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.

    During no wind conditions, I could throttle back to about 1/2 or 3/4.

    A direct drive GWS IPS motor provide a lower current alternative.

    For 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 current drop.

    The 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.

    The 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 Pack.

    My 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!

    Micro Joule Classic Cruiser video - 5MB

    Manufactured By:

    Distributed By:

    Global Hobby Distributors

    Global Hobby Distributors
    18480 Bandilier Circle
    Fountain Valley, CA 92708
    TEL (714) 963-0133

    Comments on RCU Review: Cirrus Micro Joule System

    Posted by: CRAZYRYAN on 03/29/2008
    How do I go about ordering one? Can't seem to find a resource on a website that sells then but I happen to find aero micro and there seems to be an error on the site. I want to convert rubber power to electric and one of the models is 20.5 inches should work.
    Page: 1
    The comments, observations and conclusions made in this review are solely with respect to the particular item the editor reviewed and may not apply generally to similar products by the manufacturer. We cannot be responsible for any manufacturer defects in workmanship or other deficiencies in products like the one featured in the review.

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