Power Distribution & Motor Mounting

A two part updated today. After last working on my concept layout I was without an internet connection (modem failure) to publish my progress.

First up I started fleshing out an idea for power distribution. This idea being a single PCB with all 5 of the ESC’s and a battery connector soldered directly to it. Currently I have not looked at the electrical feasibility of this at all and I expect it could be challenging given the high currents being dealt with. That said other similar sized copters have implemented the same concept successfully. One possible downfall of my approach is trying to do to much in to little space. Complications (read challenges) I have introduced include:

  • ESC’s on both sides of the board, this might make a simple one side +ve the other -ve approach more difficult.
  • Bullet connectors included on board, individual traces will be required rather than simple +ve and -ve planes.
  • 100mm length limit as this is the large size offered by http://dirtypcbs.com/
  • XT60 connector directly soldered to the PCB. This may in fact be a very bad idea a for reliability, a loose battery may tear the connector from the board and fixing that will not be a quick swap without another fully populated power distribution board (5 ESC’s!) ready to go.

MC2 006

In any case getting this concept for power distribution together has meant that I have shuffled the overall layout about again. The power distribution board itself has been dropped low and pushed forward beyond the front boom. The fuselage structure will need to extend forward to protect this. The thrust vectoring servo’s have been repositioned in a vertical orientation in an attempt to keep the fuselage narrow, servo horns were added for a more complete picture.

MC2 005

The next development was to create the first draft of the motor mounts. The concept here is that the motors would first be attached to the mount before the mount is subsequently attached to the arm with its opposite number. I intend to add extra fasteners at the tips of the arms to hold the two halves together. I also need to add some thickness below the motors so that the two halves support each other at the tip whilst leaving a gap at the back end so that the two halves clamp on to the carbon tube.

MC2 008

Whilst the layout hasn’t changed markedly here it does illustrate what the motor mounts look like installed. An entirely different solution will be used for mounting the rear motor.

MC2 007

Power and Control

This update is only a small one with the inclusion of the flight control board (blue) and the motor speed controllers (purple). Positioning of the speed controllers is very temporary. I would like to investigate mounting them directly to a power distribution board to reduce wiring. As the layout develops so will my thoughts about what form this board may take.

Given this is looking more and more crowded I also looked at what impact increasing the motor spacing has. Currently, and in all pictures to date, the motor axis are on a 250 mm pitch circle. Increasing this to 280 mm increase space quite dramatically however I feel it is to premature at this point to be increasing the size without determining that this smaller size can’t be made to work.

I have also be wondering on the sense of my idea to use a boom for the rear motor. The popular plate based design holds appeal for ease of assembly and layout however I tend to design within the constraints of fabrication techniques easily available to myself and currently that is 3D printed ‘connectors’ and off the shelf sections.

Components added are:
Flight controller: Naze 32 “Full” Flight Controller (the “Acro” version would also be suitable)
Speed controls: Afro ESC 12Amp

MC2 004

More OEM Bits

This evenings work was modeling a couple more of the OEM parts I intend to build the prototype with. All parts I am working with so far are the same pieces used in the development of Mk.1. Parts added this evening include the thrust vectoring servos and the battery. I had intended to use a bigger battery but putting this one in to the development layout has shown that available space may have other ideas in that regard, an increase of motor spacing may be required as I progress.

Components used are:
Servo: Turnigy™ TGY-9018MG MG Servo 2.5kg / 13g / 0.10
Battery: MultiStar Race Spec 3S 1400mAh 40-80C

MC2 003

MC2 002

Prototype Layout

Initial layout planning for my MultiChase project has started with the modeling of OEM parts to be used. Seen in this image are the motors with 6030 propellers and the three main booms.

This is the second conceptual layout to be trialed and will be designed from the ground up rather than using pre existing construction blocks as with the first iteration.
MC2 001