Arctibaby and APM2

After getting the HobbyKing MicroQuad put together rather nicely, I was having a lot of problems with one of the motors running erratically.  I thought it might be a problem with the motor or ESC, but Andreas suggested swapping out the KKBoard and seeing if that would help.

We swapped in his APM2, and it flew rather nicely, modulo some PID tuning to get rid of the shakes.
Impressively, the APM2 is almost the same dimensions as the KKBoard.  As far as I know, this is the smallest quad that's run with the APM2, but I'm happy to receive any corrections.

I'm rather encouraged, it will be a lot of fun having a tiny platform that I can fly indoors!

Two nifty vendors of tape and heatshrink

Just to prove that the Internet has specialists in just about every human endeavor:

• The Tape Brothers (with links to nice colored vinyl tape)
• Buy Heat Shrink

Hobbyking Micro-Quad build, part 3

I hooked up the battery, bound the transmitter, and tested to see which motors needed to be reversed. I had tried to think of some clever way to determine the motor rotation prior to soldering the motors, but couldn't think of any.

It turned out not to be a problem.  It's only a couple of seconds to desolder and resolder the wires in a swapped configuration.  I found it most convenient to leave the middle wire soldered and swap the left and right wires.  In this picture you can see the swapped state.

Here's how I attached the receiver.  Instead of using four 3-strand servo connectors, I used two.  You can do this because you only need one power connection.  The cable on pin 4 is connecting the signal, power, and ground wires.  The cable for positions 1-3 is connected to the signal pins only.  I made these cables with my crimping kit.

Note that I had to cross two of the signal wires where the attach to the control board.

(UPDATE:  Ignore everything below. I spent way too long trying out all kinds of things for the props.  I ended up using a hammer and banging the props directly onto the motor shaft. Works great!)

Previously I thought I could just use the prop savers to hold the prop in place without having to hollow out a hole in the pro to match the prop saver dimensions.  This turned out to be a false hope, as the blades wiggled vigorously as soon as power was applied.  I reversed the prop savers from their previous orientation so that the small end of the prop saver was exposed.  It should just line up with the end of the propeller shaft.

I used a 5/32'' drill bit to ream out the prop hole.  For strength, I didn't drill all the way through the prop, but just enough so that the prop would fit onto the prop saver. Holding the drill bit in some vice grips worked nicely.  Trying to use the electric drill broke the test prop.

I had some crud that didn't separate cleanly when the drill bit was removed... some tweezers took cleaned things up nicely.

Here's the props mounted on the prop saver using therabands.

Note: balance the props before you ream them out.  The small prop hole fits nicely onto a paper clip, but once the hole has been reamed out the balance is thrown off by the uneven connection between the paper clip and the inside of the hole.

I used gorilla superglue (with the embedded rubber cement) to glue things up.  Here's how much glue I used for the joints.

I applied it to one side, mated and jiggled the two sides to spread the glue, and then mated the joint to the proper position until the glue cured enough to hold the joint.

I cut some craft sticks to wipe off the excess glue from the joints.

Here's how much glue I used for the arm supports.  I also applied a bead of glue along the edge.

In order to keep my fingers out of the mess as I aligned the pieces, I held everything together with pliers.  I still got some on my fingers and blobbed some glue over the body.  If I did this again I would try dry-fitting everything and then wicking thin CA into the joints.  The Gorilla CA was a bit too thick for wiking.

To save weight and space, I took the Orange receiver out of its case and wrapped it in 3/4'' shrink tube.

I had to swap the mounting holes for the legs so that they didn't interfere with the mounting of the board.  If you're flying in X configuration, be sure your legs are lined up with the arms.

Here you can see that this allows plenty of room for the board.  There was vibrations even with this configurations.  I later added two more layers of gyro tape and the anti-vibration pad that came with the kit.






to be continued...




Note: If you're using kapteinkuk XCopter 4.7, the numbering of the rotors has changed:

 ;   View from above
 ;      Forward
 ; M1,CW     M3,CCW
 ;   *         *
 ;    \       /
 ;     \    /
 ;      \ /
 ;       +
 ;      / \
 ;     /    \
 ;    /       \
;   *         *
; M2,CCW    M4,CW

Superfly Canopies and Battery Holders

Here's some interesting approaches to mounting batteries on the SuperFly.

Murman made a coroplast canopy for SEFF combat.

Wam74 says: "I don't run a canopy and wasn't totally happy with just velcro on the battery. So I made a holder. Straightened a paperclip, bent it into a hard C the width of the battery and pushed it up through the foam from the bottom side. Cut the wires 1/4" above the top of the battery (topside), bent them into opposing hooks and stretched a 1" O-ring between the hooks, securing the battery. I still leave the velcro in place to keep it from sliding around on my less than skillful landings."

Murman did this: "I modded my SF so that the canopy would break away in a crash. I used velcro to hold the battery to the canopy and then tiny rare earth magnets to hold the canopy to the deck. Since the battery is the heaviest part of the SF, my thinking was that if it broke free in a crash then the SF itself wouldn't get damaged. It actually worked very well and I'm sure it saved having to make some repairs."



The battery is nicely protected as you can see.

Flying wing CG calculator

Here's a nice CG calculator for flying wings.  I haven't tried it, but people are saying nice things about it on RCG.  I'm going to try it out with the Zephyr II measurements and see if it gets the same COG as Chris did.

We're featured in a nice AP Drone article!

A nice article by AP's Marcus Wohlsen went out today.  Andreas and I met with him last last week and demoed some of the work we've been doing here.

Best pictures:

• Fox News
• Daily Mail (best picture layout)

BERKELEY, CALIF. (AP) - Sharp-eyed dog walkers along the San Francisco Bay waterfront may have spotted a strange-looking plane zipping overhead recently that that looked strikingly like the U.S. stealth drone captured by Iran in December. 

A few key differences: The flying wing seen over Berkeley is a fraction of the size of the CIA’s waylaid aircraft. And it’s made of plastic foam. But in some ways it’s just like a real spy plane. 

The 4 1/2-foot-wide aircraft, built by software engineers Mark Harrison and Andreas Oesterer in their spare time, can fly itself to specified GPS coordinates and altitudes without any help from a pilot on the ground. A tiny video camera mounted on the front can send a live video feed to a set of goggles for the drone’s view of the world below.

[...] 

If you've come here by way of that article, welcome!  Check out our youtube channels if you want to see some videos of the work we've been doing:

• http://www.youtube.com/user/marhar2
• http://www.youtube.com/user/oesterer

And here's some links to past posting that might be of general interest to people curious about homemade drones:

• Drone Downed in Stormy Sea, Rescued by Daredevil Sailor!
• ArudpilotMega2 + Arcticopter III maiden
• Ritewing Zephyr II + Ardupilot Maiden

And some representative build details.  If you're interested in more details, there's plenty on the site or feel free to drop me a line.

• Turnigy Micro-Quad build, part 2 -- in progress, so I'll have a nice indoor drone.
• DIY FPV Goggles Update -- my ongoing quest to do things on the cheap!
• My Farm Fresh Quad Helmet -- a cheap idea that's worked quite well

The plane is a Ritewing Zephyr II, with an ArduPilot Mega control board. Lots of details here.
The quad is a RadicalRC Stinger, with an ArduPilot Mega 2 control board.  Lots of details here.

Turnigy Micro-Quad build, part 2

 Continuing from part 1... here's the power cable attached to the bottom of the board.








Check the voltage on the power pads, you should see full battery voltage.  You'll also notice that the positive pad is on the right looking down with the arm pointed at you.

 A lot of ESC wiring needs to be cut off in order to solder the ESC directly onto the frame.  It turns out this is a lot easier than it looks, so don't sweat it.

 Here's about how much to cut off for the power.  Put a blob of solder onto the pads, then cut and tin the ESC power wires.  Position the wired onto the blobs, touch your soldering iron to the wire, and the tinning solder melds smoothly with the blob on pads.

 Trimming the shrinkwrap a bit helped.

 To verify, plug in the battery and measure the voltage on the control cable.  it should be about 5 volts.

 Do the same thing to the three motor leads of the ESC.

 Do whatever programming (if any) is necessary on your quad controller board.  My notes on doing this for a KK Board are here.

 It seems you're supposed to attach the KK Board (if that's what you're using) onto the leg bolts, but they're too short.  I used a triple layer of double-sided servo tape.

 Attach your receiver and hook up your motors to the quad controller board.

 Now here's a very weird thing.  I trimmed the motor wires just as I trimmed the ESC wires, but I could not get the to tin at all.  I have no idea why this was -- are the wires coated?  Anyways, I mashed the wires into the solder.  I'm hoping this is good enough... if not and I have a cold solder joint I'll try and figure out the solder problem or buy another motor.

Fortunately, I had done just the one motor as an experiment.  For the other three motors, I tinned the ends without cutting the wire, and attached them while just folding the wires back.

This worked well and is what I recommend you do. (update: brosius85 points out that the motor windings are coated with varnish that's heat-resistant in order to handle the high temperatures of the motor.  That's why I couldn't just burn off the coating with the soldering iron.  Thanks Brosius85!)






Continued in part 3...

Turnigy Micro-Quad build, part 1

 I'd been looking for a small quad kit for a while... something that I could fly inside the house without making it sound like we were under attack.  When HobbyKing announced their micro-quad I thought I would give it a go.

It arrived very nicely packaged.

 And inside the package, everything very tidily laid out.  Fiberglass body parts, and an integrated power distribution setup.  More on this below.

 Parts List:

• Turnigy Integrated PCB Micro-Quad (KIT)
• 5030 Propellers (Red) - 3xCW and 3xCCW
• 5030 Propellers (Black) - 3xCW and 3xCCW
• TURNIGY Plush 6A Speed Controller (buy 4)
• Turnigy 1811 brushless Outrunner 2900kv (buy 4)
• USBasp AVR Programming Device
• HobbyKing Multi-Rotor Control Board V3.0
• Turnigy 800mAh 2S 20C Lipo Pack (USA Warehouse)

Update: Now there's a receiver-ready prebuilt ARF which includes a KK2 board.

Ikea-style instructions!

 Here's the power distribution part of the board.  The power side of the ESCs are soldered directly onto the PCB pads, and there's a spot for a JST connector to be soldered.

 The flip side (which is the top) has the four wires necessary to interconnect the positive and negative poles.

 The laser cut fiberglass turned out to be really easy to disassemble.  Wiggle the pieces a bit and they will twist loose with no problem.  I used a pair of small pliers to snap off the little connector pieces.

 Here's the power train, minus batteries.  Hobbyking sales hint if you're in the US:  If the batteries you need are so stocked, order them  separately, and get them from the USA warehouse.  This will speed up your order shipping from the International warehouse since there won't be any LiPos that will cause slow shipping.

Here's one set of everything.  Vendors must love multicopters, since they sell 4x or more of all the components!

I had planned on using the nice-looking spinners that came with the motors, but the props didn't fit.  I didn't want to spend time hollowing out the props so I'll use the included prop savers instead.  You won't need the included bullet connectors or shrink tubes.

 Here's my KK board, installed on my East Bay Standard control board carriage.  We won't need the carriage for this tiny unit!

 The King was out of stock on the M2x8 bolts and M2 lock nuts.  That's a shame, coz buying them locally cost an arm and a leg:  36 and 28 cents each, respectively... ouch!!  I tried fitting some cheaper imperial screws, but couldn't find any that were noticably cheaper that fit to acceptable tolerance.

 Snapping off the retaining pieces as noted above.

 Here's the frame dry-fitted together.   It holds together pretty nicely, so you can put off gluing the pieces together until after all the other construction steps.

 Here's the top shield.

 The holders were a bit wiggly.  After they're screwed onto the board it's pretty secure.

 Here's the included hardware.  It's everything needed except for the motor mount.

 Everything dry fitted together, with the top bolted on.

 Here's the leg mounts, assembled and ready to attach.

 The shield bolts seem a bit short.

 Everything attached, looking from the top.

The fully assembled frame, bolted but not glued.

 The motors, motor mounts, and spinners (which won't be used -- see the next step).

(UPDATE: ignore prop information below.  see part 2 where I recommend using a hammer to pound the props on.)

 Here's the prop... notice the tiny hole.  Let's try the prop saver!

 You will need a 1mm hex wrench to install the prop saver.  Put the big rounded end out.

 The motor includes an o-ring to attach the prop.  I've had much better luck with theraband prop savers.

The small prop hole doesn't fit onto the end of the prop saver, but if you wiggle the prop a bit it will fit snugly on the end.  Don't forget to balance the blades.







To be continued...