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Posted by prodriverex | Aug 10, 2014 @ 09:58 PM | 975 Views
I am attempting to build a ball drone based on the popular Japanese Ball Drones discussed here:

And base on the weight calculation, I go by prop size since I have a few lying around. The preferred prop size shall be 12".

Another project here discussed the VTOL coaxial as early as 2007:
And in it the TS hg1 stated:
A good motor + prop combination will give you in the range of 8-10 grams of thrust per watt, and you want at least 50% additional thrust for acceleration. So a 1000g uav will need 1500g lift, which means that you need 1500 / 8 = 187.5 watt motor. Because these motors seem to be most efficient in the middle of their power range, you probably want to select a motor with close to double the peak output that you need. So in the 1000g uav case, that would probably be 375 watts. For a 300g uav, you can probably get by with a 100 watt motor.

The prop size isn't that much of a factor, but different props vary greatly in their efficiency - I saw 30-40% differences in performance between different designs of the same size. For a given shape, changing the diameter as much as 30% often made little difference in overall system efficiency.
But finding a motor with the right amount of thrust for 12 incher is not easy.
One I found from HK is http://www.hobbyking.com/hobbyking/s...tor_Mount.html
This is a 50 bell...Continue Reading
Posted by prodriverex | Jul 14, 2013 @ 05:27 AM | 1,698 Views
Yah yah yah I know many have said the Alexmos board has current limitation of 2.5A to 3A so how is someone going to use this board to power a RED with lenses altogether weighing 7kg?

Well i dunno.. that is why I'm here to investigate..

Thanks to Jackerbes' unrelentless pursue for truth in motors windings..
His contribution to this forum on Motor Design has been tremendous..

First of all, understanding of the motor formulas important for this BLDC motor built.

1. Kv is not all important here. Ri, internal resistance of the motor windings whether over 2 phase under WYE/Star or over single phase under Delta termination should technically between 5-15ohms in order to keep the current drawn from the controller board within safe 3A operating limit if you are using 3S or 4S.

2. Find a motor to rewind and you need to know how many poles and slots and key into: http://i.caendle.de/dev/test2/ to find out the diagram for winding.

3. Some original motor came with 2 to 4 strands of wire wound in parallel. Doing that is the same as using a thicker diameter wire to wind around the slots but the latter method actually waste more spaces.
But otherwise, there are reason for using single large core as stated by jackerbes here: http://www.rcgroups.com/forums/showp...&postcount=302

4. Reducing from 2 parallel wires to single wire actually double the resistance and double the number of turns, thereby quadruple the resistance and bring the Kv down by 4 times although it is not an...Continue Reading
Posted by prodriverex | Jul 11, 2013 @ 01:32 AM | 2,437 Views
This blog detailed the salient points about series connecting the DPS-600PB into a capable 12VDC PSU or 24 or 36 or 48V DC PSU.

The capability of this server grade PSU is due to the high current output stability of upto 47A and some tested even higher.

Much of the instruction and care are taken from these few threads. I do not take any credits here as I didn't start this mod myself. I am purely documenting this as part of my work diary.

1. http://www.rcgroups.com/forums/showt...1581061&page=1

The beginning:
1. From rchelijc:
Originally Posted by rchelijc View Post
Warning! Build at your own risk!

Alright, disclaimer aside, here's the wiring diagram for how I built mine. It's based on a pinout diagram in another thread, and this description of the pins which was also in that thread:

PIN ------------ Ribbon Wire
1----------------- +5VSB, not on ribbon wire
2----------------- +5VSB, not on ribbon wire
3----------------- +5VSB, not on ribbon wire
4----------------- 3 (Controls fan speed)
5----------------- -12V, not on ribbon wire
6----------------- 5 (PsKill)
7----------------- 6 (not sure what this one does)
8----------------- Ground, not on ribbon wire
9----------------- 8 (Voltage Adjust)
10---------------- 4 (PsOn)
11---------------- 9 (Current Share)
12---------------- 7 (not sure what this one does)

Shorting 6-8-10 turns the PS ON. I put a switch here.

(Note: Tjinguy at his site shows that he shorts pins 6-9-10
...Continue Reading
Posted by prodriverex | Dec 02, 2012 @ 11:58 PM | 2,671 Views
Many have heard of reflashing Simon K firmware and yet many had read but not attempted to do it.

Being The Engineer, I should not shunt away from the vast pages of info to read and attempt. Therefore, gathering all the tools necessary from past 2 months, finally took the plunge when an opportunity arose to build an Octocopter.

1. First, we need the programmer. I got this from HK:
USBasp AVR Programming Device for ATMEL proccessors
The device came with 10pins serial connector cable to the PCB end. At the other end of the cable there is a choice of 10 pins and 6 pins female socket.

Then I have to determine what type of connection I want to made in order to touch the ESC. Since I am flashing the HK F-40A ESC which has the pads in place, it is easier to made the cable and hotglue it to a cloth-peg style as shown. I learned this from this thread.

Here's the style I copied from:

As to which pin from the pad goes to which pin in the programmer, you have to refer to this diagram:
...Continue Reading
Posted by prodriverex | Oct 17, 2012 @ 11:54 PM | 2,657 Views
Here's the mod Deans to accommodate anti-spark. However, this is the battery side.

Really, nothing to mod except I just superglue them together and clamp it till dry with heat gun and then shrink wrap them after soldering the cross link and to the battery:

The other connector is the balancing connector wired to adapt Schulze charger. Not ready to wrap yet, waiting for a resistor to be added so that the charger will auto recognise the charge current for this pack.

Here's another view. I have pumped in hot glue into the hole where the shrink did not close all the way on the main connector.
...Continue Reading
Posted by prodriverex | Oct 17, 2012 @ 11:43 PM | 3,327 Views
I am copying and pasting the following info from my entire build log just so to focus on the PDB alone.

The objective is to hard mount all the ESCs for the multirotors on a single plate of PDB, double sided. Since there is none in the market to handle the higher than expected current and power, the only way to test the idea is to build one, out of acrylic and copper sheet.

So here goes.
Now that the frame and motor mount and motor is done.. time to move up the base and think of how to mount the ESC.

My design believe in having a low CG and all components should concentrate to the middle as much as possible. Even my base plate is very small at 100x100mm for a 750mm Quad.

So to reduce wire and cable clutter, I want to formulate my own PCB to carry those power.

So the idea came from http://hackaday.com/2008/07/28/how-t...gle-sided-pcb/

Its interesting to learn that one can laser print onto practically any flat surface, literally.. But instead of meddling with pungent chemicals, i decided to adopt my own method..

Here's the PCb plan on drawing:

S that means, we can employ the same manner to transfer these lines onto a sheet of copper! Voila!

But which paper or foil to use? I suppose using the aluminum foil looks better as I can see how the print out will turn out.. But before I can do that, I think it may sense to reverse the color like this:

Reason is simple. the track should be clear of any printing so we...Continue Reading
Posted by prodriverex | Sep 14, 2012 @ 11:07 AM | 4,407 Views
Its all starts from here.

The arrival of the CF parts in March 2012:

But only in Sept I started working on this.
100x300x1.5mm sheet cut into 100x100. That's how small I like it to be to keep weight down.

The usual, 4 corners with holes, act as pivot for the boom too. Make last minute change to include a swing-close design.. had to drill many holes and file them to shape.. not very nicely done.. had to oversize them to get a smooth swing.
...Continue Reading
Posted by prodriverex | Sep 13, 2012 @ 07:05 AM | 2,797 Views
Sometime in Feb 2012, I started this project after deciding I should do something like a quad with the spare material lying in my workshop..

So I tried my hands on milling using a drill press and did a cross-joint.. looks ok:

Days later, went to buy some low Kv and cheap motors and mounted them on:
...Continue Reading