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OS' CCcopter

This page shows another one tiny quad based on the CopterControl board (aka CC, thus the name of the airframe).

The CC is a little single-board product from the OpenPilot project. It has many features of its big brother, for example, the same USB bootloader to update firmware, the same USB and serial telemetry link, the same UAVTalk protocol to talk to the same ground station software (GCS), the same mixer settings, and many other uavobjects are also shared with full OpenPilot system.

But using the same powerful STM32 32-bit 72MHz CPU, it is only 8g (8.5 with servo headers fitted). And it fits perfectly for such small quads with only 4" props. Stay tuned!

Airframe pictures

Here is a whole ready thing. It uses 3.3v powered OrangeRX DSM2 Spektrum-compatible satellite which is under the CC board. You see 3 wires soldered to the CC which go to the Rx (GND, +3.3Vcc, serial input) and a grey antenna wire near the USB connector. Other build details are below.

Timeline

February 09th, 2011. Finally received 4" props. So the building of the CCCopter is a matter of time. All parts are now in hands.

February 20th, 2011. The quad is ready. But there is a problem with propellers. They are mounted using original motor accessories - prop savers. And I have to do something with very high vibrations. Either replace prop savers by spinners (need to order them), or do something else. Still thinking...

Decided. Ordered 4 propeller adapters from ebay...

February 21th, 2011. The real problem was with highly unbalanced propellers. After that... See below flight video!

Flight video

This flight is really first after propeller balancing. Absolutely no tuning was done, no settings were altered - just plug and play solution. Now when we see that it works, we can cut wires to save some weight. The video was cut unplanned, not such a good flight was expected. So sorry for the quality!

Airframe Info

Motor to motor size

165mm

Weight without battery

102.9g

Used battery weight

46.8g

Total flying weight

149.7g

Cutting some wires, it is possible to save few grams too.

Complete build instructions

Equipment

Type

Notes

Main frame

Carbon Fiber Square Tube 750x3x3mm - 1pc

Plywood motor pads 21x18x1mm - 4pcs

Glass fiber central plate 36x36x1mm - 1pc

The frame design is quite simple but rigid enough for the size - 165mm motor to motor. It was assembled using one square carbon tube, 4 pcs of plywood and one glass fiber plate. Below are simple instructions. 

  1. Cut 750mm carbon tube to 4pcs of 186mm length - it gives about 6 mm for cut points, 2mm per each.
  2. Cut 4pcs of plywood motor pads 21x18x1mm.
  3. Drill six 1.7mm holes: 2 for motor mount, and 4 for pad mount.
  4. Drill one 4mm hole for motor shaft.
  5. Using cyanoacrylate (CA) glue, glue pads to the tubes. Use sandpaper first to glued surfaces. This gives 2 arm assemblies for the frame. Each has 12mm space between tubes for ESCs.
  6. Cut one 36x36x1 glass fiber central plate. Mine was cut from pcb material and then etched. Round corners and edges if you like.
  7. Glue arm assemblies to the central plate - one goes above, another under the plate. Note orientation of motor mounts on images.
  8. Drill 12 1.7mm holes for threads (see images).
  9. Drill 4 3mm holes for the CC board mounts (31.5mm between each pair).
  10. Drill 8mm central hole just in case of some wiring or to save some weight.
  11. Use some synthetic threads to fix motor mounts and central plate. Apply some CA to the threads to fix them.

Motors

18-11 2000kv Micro Brushless Outrunners (10g) - 4pcs

Motors come with radial mounts and prop savers. But you have to order some prop adapters to have a solid system since prop savers give too high vibrations.

Also I recommend to order at least one extra motor. Their build quality is not perfect. Mine were not fixed in their radial mounts, and few mounts even didn't have threads to the ends, so grub screws did not fix them at all. I had to fix every motor carefully using thread locker.

Propellers

4x2.5 Propellers (Standard and Counter Rotating) - 1-2 sets

Those small 4" propellers have 4mm holes. They should be ok for the prop mounts, but in fact they aren't. So extra prop spinners are recommended (see below).

You may want to order 2 such propellers sets (3+3 in each) just to have some spares. You may install even 5" props on almost the same frame (need a bit longer motor mount pads or carbon tubes), but I wanted a tiny quad, so I went for 4".

Important note: despite their small size, propeller balancing is a must. After that prop savers work just fine (see video).

Propeller adapters

CNC 2mm Motor Shaft Propeller Prop Adapters - 4pcs

Since the last problem I have is with vibrations, I ordered those prop adapters from ebay. It seems that HK does not have 2mm to 4mm adapters, that's sad. But without good prop mounts vibrations are very high, and quad is unfliable (and even unholdable in hand, have to say).

Note: they are not necessarily if you balance your propellers. It was found a bit later.

ESCs

Turnigy Plush 6A - 4pcs

These ESCs are programmable and are able to run at 400Hz update rate. Performance-wise, it is recommended to increase default 50Hz update rate to 400Hz via UAVObject Browser since the GCS Config gadget does not support 4 different rates yet.
 
The ESCs are soldered to motors (note the rotation direction) and put between each frame arm tubes (see images). Wires should be cut to save weight but I didn't do that yet. They are fixed in the frame using one zip tie for each. Also note that the central frame has some black insulation tape pieces on the edges to save ESC wires from damage.

Then all power wires were soldered together and put between the central plate and the CC board. One of ESCs is connected to the 1st servo port of CC to provide power to the CC board and signal to the ESC, and another 3 ESCs use only signal wires - their connectors are rotated 180deg for this (see images).

CC mounts

MK plastic 15mm mouns - 4pcs

The MK plastic 15mm mounts were used to install the CC board. If you cut some wires then you even can use 10mm mounts. I didn't do that yet.

Main board

OpenPilot CopterControl

The brain of the quad is the CopterControl board. It is installed using plastic mounts and plastic nuts.

Receiver

OrangeRX satellite receiver

The CC supports Spektrum satellite protocol directly. But it requires 3.3v supply (there are also reports that it can handle 5.0v but I didn't try it). So I had to solder the satellite wires directly to the CC board instead of FlexiPort. Black wire goes to the ground, orange wire to the +3.3v Vcc (digital regulated +3.3v source is used), and grey wire goes to the Rx pin of FlexiPort. The receiver itself is placed between the central plate and the CC board, so only antenna wire is visible near the USB connector.

Battery

LiPo 800mAh 2S 7.4v

Any decent battery should be ok.

Landing skids

 

None at the moment.

Transmitter

Spektrum DX7

 

CopterControl settings

Initial setup is done with the SVN Rev. 2814 firmware. The following settings were used (download settings in UAV, XML or INI format):

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