Air Craft

Air Craft
CD-DIY Motors

Click Here to Order         NEW!  NdFeB Magnets are now Pre-Installed!!

Pictured left is the new Air Craft CD-DIY Set, ready to run for RC model aircraft.  The set comes as pictured, with these items included:

* CD-ROM motor 17grams1, with NdFeB N45 6.0x2.6x1.0mm magnets installed
* Pre-Wound Stator! 0.32mm wire, 32T Delta (20.2mm x 5mm Stator)
* All-Aluminum Prop Saver for APC
* Bands for the prop saver mount
* Motor base mount
* Mounting screws and washers

Motor is 17 grams, but the steel backplate mount adds 6 grams.  You can lighten the steel mount, or remove it completely when attaching to a plywood or fiberglass bulkhead.

Notes (June 27):  We stay so busy here at Air Craft that I rarely get the chance to experiment as much as I'd like to.  However, I did take some time last week to explore this CD Motor set, and boy am I having fun!  I mounted the motor in my ST Model Micro CAP T3D.  I started with an APC 7x4 SF prop and PolyQuest 600-2S pack (~4.3A).  With this combo, hovering performance and top speed was much better than with the IPS-A which had previously been installed.  I then changed to the APC 8x3.8 SF prop and ...Wow!.. it is really amazing (~6.2A with fresh pack, static).  I've had to retrain myself on the throttle stick, as I kept finding myself 100 feet up, when trying to maintain hover!  And given that my Micro CAP has a number of heavy components installed (it's a test mule), the current 150g weight could easily come down to 120g or less.  Having a good time!!
Assembly Instructions
The motor pieces come assembled in the package, but the stator is not fixed.  You have to first disassemble the parts, and perform a few easy steps to complete the motor.

There is a clever locking ring inside the shaft housing so you can easily remove or reinstall the bell and shaft assembly.  So first just grip the motor mount and bell, and pull them firmly apart.  Now remove the stator from the bell.  The wires on these small motors are quite thin, so you need to be careful not to break them. Fold the wires up together so that you get a firm grip on all three, then pull the stator out with even tension on all three wires.  DO NOT attempt to remove the stator by pulling on just one or two of the wires!

We think the supplied pre-wound stator is just about perfect.  It allows prop size up to 8x3.8 on two cells, or a small prop on three cells for fast models. Due to limitations of the winding machine, the wires coming from the stator are a little bit short.  So first you should twist up some extensions (about 4cm or 1.5 inch is enough) made from servo or other small wire which matches the wire size on the stator leads (or just slightly larger).  Solder these extensions to the stator leads. Insulate the motor wires with heat-shrink tube (1mm size is good), and install connectors. (MP-Jet 1.8mm recommended)

Loctite the stator to the brass shaft housing (use green loctite #638 , or any green "sleeve retainer" permanent loctite).

The bell and shaft may not be perfectly true.  Insert the bell/shaft assembly into the brass hub, but not far enough to engage the locking ring.  Grip the motor mount and turn the bell slowly, watching the gap between the two parts.  If the gap varies as you turn the bell, consider which way the shaft needs to be tweaked.  Grip the bell in one hand, and apply pressure on the shaft (with thumb on other hand) to adjust the alignment. Repeat until the gap between the mount and bell stays constant as the parts are turned.  It usually takes me only two adjustment attempts to get it just right...
Now that the bell and shaft are true, install the wobbly adapter so that it is touching the bell evenly.  Install both screws, and tighten them.  Now run a little fast CA glue around the perimeter of the junction between bell and adapter, and hit it with some CA accelerator.  The bell will stay true to the shaft now...

Finally, re-assemble the Bell to Carrier, and route wires so that the bell does notrub on the stator wires.  You may want to cut a slot in the side of the Backplate to allow the wires to clear more easily, or drill a hole in the backplate for the same purpose.

Have fun!!

Tested with ET-P0700-2S Lithium Pack, and using Std 0.32mm x 32T Winding as supplied

RPM  Torque (g/cm)  Input (V)  Input (A)  Input (W)  Efficiency(%)  Prop  Magnet
8800 188 7.1 3.4 24 67.40%   APC 6x4  N45 NdFeB 24pcs

Controllers for Li-Po:

Castle PHNX-10
Hacker HM-04-3PBEC

Controllers for NiMH:
Jeti JES-04-3PBEC, JES-08-3PBEC

Motor Connectors: MP Jet 1.8mm Gold  MPJ-21011-BULK

Battery Packs Lithium Polymer:
Poly-Quest AC-PQ0850-2S  AC-PQ8500-3S (no connector)

E-Tec ET-P0700-2S  ET-P0700-3S (comes with JST connector)

Battery Packs NiMH:
KAN  250mAh

  BLOCK Packs  K0250-BL**P  (no connector)

   BRICK Packs  K0250-BR**P  (JST connector)
KAN  650mAh
  BLOCK Packs  K0650-BL**P  (no connector)

   BRICK Packs  K0650-BR**P  (no connector)

Battery-ESC Connectors:
Deans Micro (set) D-1222
(you may want a second set to make charge cord)


Instructions for Installing Magnets (only applicable to  AC-CDMOT-ORIG Motor Set)
See instructions on installing AC-CDMOT-ORIG in GWS EDF 55 and 66 Fan Units HERE
(magnet placement is different for EDF)
Set the bell-shaft assembly in a vise or on a tube such that the cup is facing up.  Fill the bell with CA Glue De-bonder, or ACETONE.  Let sit for a minimum of 4 hours.  Carefully apply pressure in gap between bell and ring magnet with a knife point.  You should be able to crumble a section of the magnet away, at which point the remainder should easily come free.

 (see bottom of page for customer suggestions and alternative methods)

4) Here are the items you'll need to easily install the 24 accessory magnets and avoid polarity mistakes:

*Two colors of fingernail polish. I bought mine at the 100 yen ($1.00) shop.
* Two box-cutter knives
* A black marker
* The 24 magnets
5) Allow the magnets to form a single stack of 24 pieces.  They'll all have the same polarity (top to bottom) at this point.  To make sure you stay oriented in case you drop the magnets (get a phone call in the middle, etc), choose either side of the stack and color the top magnet black with your marker.
6) Now turn the stack over so that the black magnet is on the bottom of the stack.  Use the box knife and gentle pressure from your thumb to separate the magnets from the top of the stack. Move each magnet to the "top" section of the knife as you go, and leave some space between each magnet, as pictured.  Continue until you have twelve (12) magnets on the knife.  Put the knife down, at least 8" (20cm) away from any other metallic object or other magnets.
7) You should have a stack of twelve magnets remaining, with the bottom magnet colored black.  Turn the stack around so that the black magnet is now on top. Slide each magnet on to the second box knife as before.  Keep the two knives well separated during the remaining steps.
8) Now color the magnets on each knife using the nail polish.  Lay the color on fairly heavily, then immediately dab all the excess away with a tissue.  Only touch each magnet once with the tissue - two dabs tends to leave tissue stuck on the magnet!
9) This is the way the magnets will be installed in the bell:  NNSSNNSSNNSS....
10) Here's a finished bell.  I have actually taken all the nail polish off with a ScotchBrite (3M) pad, but I re-colored the magnets for you in Photoshop, for clarity.  You can insert all the magnets in the bell without glue, adjust the gaps between each set of magnets, and glue them in place with fast CA in one shot.  This picture shows the magnets just flush with the top of the bell.  We have since leared that having them protrude from the bell by ~1.0mm gives a small increase in effciency.  And the magnet gaps aren't perfect in this example rotor, but the motor starts and runs very smoothly just the same...

Insulate the stator wires as shown, and install your preferred connectors. Shown are our recommended MP Jet 1.8mm Gold  MPJ-21011-BULK.

For my purposes, the stock winding (left) is just perfect.  It is just right for most slowfly/park models in the 100-250g range, including 2-cell E3D up to maybe 180g.  The same wind can be used in a 2-cell fast model of about 150g or less, or with three cells for a 200g+ fast model.

Have fun!!

Here are some more details in the photo below.  We wanted a motor that could be assembled in minutes, yet could easily be upgraded if preferred.  The dark-colored bell below is one which has been heated with a torch to remove the stock ring magnet (see instructions below for better method), and the 6.0x2.6x1.0mm magnets (included as accessories) have already been been installed. As you can see in the table below, the NdFeB accessory magnets can make a substantial improvement in performance.  However, you may find that the stock ring magnet is all you need, particularly if you plan to run a small prop, in the 4" to 5" range, on 2 cells.  At 2.5 to 3.0A, the stock setup is quite good.  If you'd like to run a larger prop, the accessory magnets will drop motor Kv substantially, so efficiency is much higher.

note: the prop saver pictured left shows steel screws, but the kit comes with light aluminum screws...

Mount the prop adapter up flush with the bell, not like shown in bottom right photo with gap.

Customer Suggestions and Modifications

Hello from the US,

I recently purchased one of your CD-ROM based motor kits. I couldn't be more pleased it works just as you said and went together without a hitch :-)

I did make one change to your instruction on removing the ring magnet. I noticed that there was no visible glue holding the ring magnet so I thought I could save a lot of time by prying the magnet out of the cup. Using a 3" piece of coat hanger wire, I built a tiny CROWBAR. I bent the wire into a hook on one end that would just fit under the ring magnet( 3/8" worked for me). I sharpened the end to look like a crowbar. Using my tiny crowbar I gently pried on the ring( aha it moved just a small amount). Working my way around and around the ring magnet gradually slid out of the cup (elapsed time about 1 minute).

Thanks for a nice and useful product!

Bill S.

Greetings from Israel,

Instead of using nail polish to mark the magnets, use Permanent Markers, like the Staedler permanent lomocolor pens. Mark "north" with a blue "X" and "south" with a big red dot.

  • Easy to apply and dries almost instantly
  • The markings have no thickness and do not have to be removed after gluing the magnets in the bell.
  • Inside the bell, one can easily tell the dot from the X, while poor lighting or glare may make it difficult to tell apart the red from the blue.

Hope this may be of help,

Amos E.


Hello from Canada,

Thanks for providing such great products like your CD brushless motors. I had some 'fun' placing the magnets, but soon after completing the build I had a very powerful little motor. I made a little 3-D biplane just for this motor. I get more daring and improve my 3-D skills like never before without the worry of bending a shaft or shattering gears on a nose in.

If you use a drill press chuck to hold the shaft it is easy to separate the assembly even after you snap it in place to the backplate/stator. Just insert the shaft or wobbly adaptor, tighten the chuck and pull down on the backplate. Viola!

Thanks again,

Dale I.


All the content on this page is the sole property of Air Craft, and may not be distributed, copied, paraphrased, or used in any way by any other commercial entity - (June 14, 2004)