Monday, December 15, 2014

There Are Four Quads.

Deadbug: A method for wiring of electronic circuits that involves attaching the components to a substrate, upside down, and then connecting the contact points, point to point.  

Saturday, I went over to SwitchElectricians place, and we spent the day messing with quadcopters.  It was a productive day, we had three different quads get completed.  

Acro quads are a strange.. They're usually an attempt at the minimum airframe to fly, but often err on the "less than minimum" amount of airframe.  That means you need to get really creative with mounting things to it, beyond the usual "hey this isn't the right size" issues that are par for the course. 

In deadbug style, here's the wiring that I did on the HobbyKing Maltese frame.  Now I'm a little disappointed I have the Velcro on there, it doesn't show my cross wiring job.

This quadcopter is flying on a set of 1704, 1900kv motors.  Spinning 5x3 props.  The battery is a 800mah 2s pack.  The flight controller is a KK clone from HobbyKing.  I'll talk about the board later, but for now, lets say I don't like it very much.  It's flying weight is very, very light.  350 grams IIRC.  

Mounting the motors was somewhat difficult.  The motors have a two available mount patterns.  The ones drilled into the motor, and then a X shape bracket you can put on it to mount to larger motor mounts.  The bracket is so large that it is bigger than the arms on the quad.   The built in bolt spacing is between two of the three bolt patterns on the arms of this quad.  To make it work, I had to drill out the smallest spacing with a slightly larger drill bit.  the washers make up for the larger motor mount holes. 

M2 screws and washers are a pain to work with.... 

The board has a fixed "forward."  So the front of this thing, unless I get some kind of adapter board, will make this a "plus" configuration quad.  When I was test flying it, this shape really messed with my head.  You'll notice the red tape and red prop, I did that before I flew it because I knew my brain wasn't going to handle the plus set up very well.    That said, it did fly, and was stable as could be expected from a board without accelerometers. 

Oh look, more deadbug.   The receiver has moved, and there's a few extra wires hanging off the chassis.  Also, the motor leads have lost 5" of excess wire.  In this picture, the quadcopter has a 3s 1500mah battery in it.  It will fit a 3s 2200 as well.  I haven't tried to see if it will balance with a 1000mah 3s in it yet. 

Speaking of balance, the female balance plug on the right side of the picture, is how we decided we were going to provide power for the FPV gear.  It means we can turn on and off the video gear, without the problems that come from switches.  And it gets the video ground as far away from the motor grounds as we can manage.  It should be "better" but I haven't thrown a oscilloscope on the quadcopter to quantify those numbers.  At minimum, it makes me feel better.

The Naze32 flight controller moved twice since the last photo.  Because the receiver came off the top deck, the cable for the Naze32 ended up being to short. 

Standoffs are a wonderful thing.  To clear the speed control wires, I had to raise the naze32 over the motor deck. Eventually I'll be using the same stack of standoffs to carry my HD flight camera, but that's for another time.  

I'm still trying to decide how I am going to dress the power and signal wires for my FPV gear.  You can see the trimmed plug for the balance connector that provides power to the FPV rig. 

The starboard elevation. I'm a little worried about the receiver location, but it's in a case, and should be able to take any hits. 

 The video transmitter doesn't stick past the chassis, so should be safe.  The front end of the X-Factor is a very, very busy place. 

Doing hobby work at your computer desk isn't recommended.. but it's what I do.   I like how it turned out.  In the next week or so, the flight HD camera mount will be fabbed up, and I'll get my hands on some circular polarized antennas.  (or make them...)

SwitchElectrician also had a project to work on.  He picked up the ultra light 250 racer frame from HK.   We built that up too.  It's flying on some 2204's, 20amp Afro speed controls, a 1.5ah 3s battery, and 5x4.5 props. 

Let me tell you, it wants to move some air.  We need to get it on a scale, but I think it may have a 4:1 power to weight ratio. You can peek in at the winding on the motors, and they're positively beautiful.  I suspect they were hand wound with how the wire is stacked on each pole. 

Saturday was a productive day.  

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