My first quad(8). H design.

3689387348?profile=originalAfter 6 months of watching the rest of you, I finally had a free weekend to begin the build of my own ArduCopter. I really was inspired by Markus's H-design of his eight engine quad copter.

 

When I checked the store, they only had four of the 2836's but after I ordered 30 more showed up instantly so I purchased 6 more for a total of 10. (in case the first flight went south). I was hoping the 6 would show Saturday morning but they didn't. So, the above picture is testing throttle with the 4 in an X flight mode. This didn't work too as the apm is at 0 degrees and the motors are off alignment. I plan to change it to + flight mode and just double up on the motors and escs like Markus did. I have GWS 3 blade 9030 props and a 6000 3s battery. At 1/3 throttle, it really lifted off quite well and I had difficulty holding it down at full throttle. I don't know the  weight of it right now but it's pretty light. I can only wonder how much it'll lift after the  other 4 motors are installed.

 

Using the H design gives plenty of space to mount esc's and run wire, plus it keeps the  central area clean for the brains. I had two 8' lengths of aluminum moulding that held garage door water barriers. I cut them into 12" pieces and used them for the central beam and some foam tape to lessen the vibrations of the copter.

I can't find any square aluminum in town but we have tons of the U stuff at the local big box store. I just found thinner sized and "doubled up" to make the motor mounts. I was really hesitant on the U aluminum as it's a little less rigid but it seems to work just fine.

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The 25amp Turnigy "Basic" ESC's I ordered didn't come with 3.5mm barrel ends so I had to solder 3 for each ESC *10 esc's I ordered. I discovered an easy way to do this quickly, not sure if the rest of you have done this but it worked very well.

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Just drill 3 holes, put in your barrel plugs (will also work with the male ends), heat, dump in some solder and hold the wire in till it hardens.. piece of cake. I did 10 esc's in about 15 min..

 

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Here is my power distribution, I made one for the left and one for the right, they'll connect together of course and be fed from the 6000 miliamp nano tech battery.

That's it for now. I plan to have it carry my go pro for  aerial photography. Perhaps my DSLR in the future after I know this is rock solid.. It's looks promising.

More to come.

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Comments

  • Developer
    Yes do not use U tubes, last year our ArduCotper team studied them a lot and final results are that U tubes are creating extra amount of vibrations. And especially vibrations that confuses IMU's. So go for round or square tubes always.
  • Lesson Learned x2. I'll abondoned my U tubing also. Once the motors spun up, just the slightest balance caused the  arms to torque which I think caused the motors to arc and stop. I actually created a square tubing one but getting the P values in sync is taxing my patience. So, I plan to build a regular Quad and get used to it, then go back to the # design. Fun Fun.
  • Nice to see another # -frame being built. During the build of my Hashcopter I found out that U-profile is really not the right material to use. It is too flexible for twisting force. This makes the whole frame really soft. I attached few pictures of my abandoned frame to my photos:

    http://www.markusjahn.net/gallery2/main.php?g2_itemId=45909

    http://www.markusjahn.net/gallery2/main.php?g2_itemId=45912

    You can see it flexes under its own weight and it was really light.

    You can easilly spot the difference of a tube and U-profile if you grab each end of a bar and try to twist it. U-profile twists easily but square tube feels really strong. What this causes when flying don't know but it can't be good.

    Flying again next weekend and doing some weight testing and more PID tuning with Hashcopter.

  • You're absolutely correct. The wires were pre-tinned and the joints were sufficiently heated to the point where the solder on the wire mixed with the ends. Thanks for clarifying. I acutally found a cold joint on one of the motor ends, it pulled right out and the solder looked crystalized inside.. I then checked the  rest and found no others.
  • I am concerned by the description of your soldering technique and would like to clarify for the benefit of others.

    "Just drill 3 holes, put in your barrel plugs (will also work with the male ends), heat, dump in some solder and hold the wire in till it hardens.. piece of cake. I did 10 esc's in about 15 min.."

    To form a reliable solder joint, both components (the wire and the barrel plug) must be heated to the melting point of the solder. If you don't bring both components up to temperature, you will get what is known as a "cold joint". This connection will be unreliable over time although it may appear to work initially.

    One way to test for a cold joint in this application is to simply pull hard on the barrel plug. A good solder joint will not budge. A cold joint will fail and the plug will pull apart from the wire.
  • Developer
    Looking good.  I'm constantly surprised by how many configurations seem to work (i.e. different weights, different arm lengths, diff number of motors, etc).  Congrats to you and also great work by Jordi on designing + building the APM + Oilpan board.
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