Bonsai Maiden Flights/Crashes

Brought the new wing out to a field and gave it a go; seems to fly well! I moved the servo arms back one notch from neutral as the flaps seemed too low and I couldn’t trim enough to eliminate the problem. I also adjusted to 30% D/R on the remote which helped a lot in the later flights.

Wing took the crashes amazingly well on the whole though the final crash resulted in the battery pulling out the piece of wood its glued too. I imagine I can just switch to strapping all the way through the wing to fix it though.

Hobbyking Bonsai – Assembly

Assembling the Bonsai with the parts I selected required a few tweaks.



First off, I had to enlarge the servo holes. I left the outside and forward edges of the stock holes alone, taking material off the other two sides to make room. I left the holes ~1/8″ undersized to ensure a snug fit which seemed to work well. I used the third hole from the inside on the servo and the top hole on the flap. According to flite test you want 15mm of flap movement for high rates and 8mm for low rates; the positions I used provide ~25mm at full range so I will have to program the controller down to achieve the targets. Using closer hole son the servo looked like it would start to interfere mechanically.

I did have to slightly enlarge both the holes with a small drill bit to get the pusher rods in.

When using the heatshrink to connect the carbonfiber rod to the Z bends, I added a little superglue as otherwise they seemed apt to come apart.


Motor Mount HolesEnlarging for Motor

The stock pre-drilled holes for the motor mount were not spaced appropriately for my motor. I used the motor’s mounting plate as a template and, using a very small drill bit, drilled new holes. The nut securing the motor shaft seemed to poke a bit too far back; to provide it some clearance I drilled a hole from the top then enlarged it slightly with a file.

Also, the bullet connectors I purchased were the correct diameter but not deep enough to fully seat the motor’s connectors. I simply resoldered the new connectors onto the motor so everything mated well.


Glueing Winglets

My patience is pretty short and the super glue pretty slow to set so I propped the wing up on 2×4’s and used some weights to hold the winglets in place while the glue sets. Given the slight texture on the foam I’m not sure superglue will hold that well (doesn’t like to bridge gaps) but I started with it and will use the same setup to gorilla glue it should they break off.


The 8 channel receiver I purchased is notably too large for the application. I stripped the case off of it which seems to get a decent fit. As it filled the compartment out I did have to cut a small notch to provide clearance to actually plugin the servo’s and ESC.

Looking at the back of the plane, the left servo is connect to Channel 1, the right servo to Channel 2 and the ESC/throttle to Channel 3. I followed this youtube video for setting up Elevon Mixing:

RC Flying Wing

I decided to add an RC plane to my flying collection. After a bit of research I settled on the Hobbyking Bonsai.

Based on others success/recommendations I went with a slightly larger motor, battery and servos than the hobbyking recommendations.

Installing the servos actually required enlarging the stock holes. I used an exacto knife to enlarge the holes but kept them ~1/8″ narrower and shorter than the actual servo to ensure a snug fit. I kept the outside and forward edges in the stock location removing material on the inside and back edge.

Installing the motor similarly required drilling fresh holes as the stock ones were not correctly spaced.

Flite test recommends smearing shoe glue onto the leading edge to make it a bit more robust which I have done. I went with a pretty thin layer that extends back ~1/2″ to 3/4″.

The full list of parts purchased was:


Mini/Micro Quad Options

I did some more research on mini/microquads as I worked on building my ~$18 version and actually found some very strong prebuilt options:

$39 WLtoys V939 Beetle 2.4G 4CH Quadcopter Dexterous Mini UFO BNF

This one is ‘Bind and Fly’ you can bind it to the Turnigy 9x remote. Its a micro quad so flyable inside and, in light wind, outside. Very similar to the $18 quad I’m building; but already built!

I purchased a V939 and have played with it a bit. Its fun but compared to other models it certainly isn’t my favourite. Still, given its small size it is likely the best choice if you plan to do mainly indoor flight.

$39 Syma X1 Series 2.4G 4CH 4-Aixs RC BumbleBee UFO Micro Quadcopter

A mini-quad, a bit big for indoor use but actually quite usable outdoors. We purchased a few of these at work and they are surprisingly robust (though given our abuse not indestructible). If you do break something spare parts are quite reasonably priced which is nice.

Includes a remote but can, apparently, also be bound to the Turnigy 9x if one desires.

Having now tried additional models; I’d say the X1 is a good introductory quad but you are likely to outgrow it pretty quick. The cost still makes it appealing but if you can spare the extra $10 I’d get the v949 listed next.

$52 WLtoys V949 Upgraded V212 2.4G 6 Axis RC Quadcopter RTF Mode 2

Again a mini-quad, the general design/parts is extremely similar to a pepped up X1 but this unit comes more highly recommended as the flight controller board is apparently notably better as is the included remote.

Unfortunately, you cannot bind this quad to the 9x as it isn’t a compatible protocol. Otherwise looks like a great choice. You can upgrade the propellors to GWS EP 5443 for front and back to notably improve the performance.

Having played with this one a bit I’d say its the clear winner if you’re looking to just purchase something with a remote. The only nock I’d give it is the lack of 9x remote compatibility.

$32 WLtoys V949 Beetle RC Quadcopter Mini UFO BNF

This appears to be a previous generation V949 and will bind to the 9x remote. Being bind and fly it doesn’t include its own controller. It seems like this one is getting difficult to find; I’d probably pass on it given the difficulty in being certain you’ll receive a 9x compatible unit.

$33 V929 Beetle 4-Axis Dexterous Mini UFO BNF

This appears to be a two generations older V949, largely parts compatible but the older electronics will talk to a 9x transmitter. If you have a 9x transmitter I’d recommend this quad as its definitely compatible. I’d upgrade the props as per the v949 with GWS EP 5443 for front and back.

Overall its quite fun to fly but the auto-flip is a bit annoying. I’m going to adjust the rates down a touch to try and avoid auto-flipping but I’ve also ordered a replacement brushed MultiWii controller to try out which aught to enliven it even further.

HackRF Lives!

I managed to get the hackrf going on a linux vm with gnuradio a week ago but getting it going on SDR# recently has proved a more compelling simple demo.

I followed the rather thorough instructions on superfro’s blog to get everything setup.

Once I had the hackrf working in SDR# I tuned into local radio stations as a first test which went great. The reception was surprisingly good and it was able to pull the station name and (depending on station) song title as well which was quite neat.

As a next test I followed the RTL-SDR tutorial on decoding Pocsag (pagers) quite successfully which was rather neat!

I have received a 900MHz and order a 433 MHz antenna to try and improve reception as the onboard antenna is disclaimed as being quite poor.

Will be fun to try transmitting as well at some point but for a reception only situation this seems like a great start.

Practice Quadcopter

As my videos may have indicated; although my tricopter is working reasonably well my piloting could still use some work.

I decided to get a mini/micro quadcopter that will work with my existing controller to learn on as they are so light weight crashes don’t seem to bother them.

After a bit of research the $18 diy quad by dave1993 looks like a winning option.

The recommended parts are:

  • WLtoys V939 RC Quadcopter Spare Parts PCB Receiving Board V939-05 $8.90
  • UDI U816 U816A Hubsan X4 RC Quadcopter Spare Parts Blade Set $1.20 (get 2+)
  • 5pcs x Coreless Motor Helicopter Motor DIY Part Size: 7×16 shaft=1mm $6.65
  • 300mAh Li-Po Battery $3.60 (get 2+)
  • Charger $2.90

Total for just the copter bits (no battery) was $16.75, with battery and charger you’re at $23.25, $28.05 with spare battery and props. Pretty cheap for a usable looking quad thats compatible with the 9x transmitter!

If you don’t already have a transmitter a cheap compatible option is the WLtoys V929 V939 V949 Beetle 4-Axis Quadcopter 2.4G Transmitter E728 $14.85. Its the same one pictured above. I don’t know what the quality is like on though it certainly appears to work.

You can also get the V939 bind and fly (so it doesn’t include a controller) pre-built. Its actually quite cheap on its own at ~$30.

Tricopter – Motor Repair

After my last crash the shaft on my rear tricopter motor was tweaked. 

Fortunately I gave each motor a spin manually before powering things on and noticed so I had opportunity to fix it. The motor was clearly rubbing and I imagine would have promptly self destructed had I turned it on.

The motor is a NTM Prop Drive Series 28-30A 750kv / 140w though I would suspect this approach would apply to other motors including those used on quadcopters y6’s octocopters and other miscellaneous multicopters.

In essence, I removed a snap ring from the base of the motor which allowed me to separate the housing from the interior. I then mounted the housing with shaft in my lathe and using a dial indicator centered it up roughly (via nocking) in the chuck.

Once reasonably centered I ran the dial indiactor on the far end of the motor shaft. It was out by nearly 10 thousandths of an inch. I located the high spot and pushed on the shaft to nock it back to 5 thousandths. The process of measuring total outage, finding high point, halving, was repeated a couple times till it was under a quarter thou out.

Remounting and replacing the snap ring I found the motor now sounded healthy. Powering it up verified all was well; disaster averted!

As an aside; the earlier part of the flight actually went quite well. Trying it in a fairly open field made flying the tricopter a bit easier and I actually managed a pretty neat steeply angled circle around 1:36 into the video.

HackRF Jawbreaker Arrived!

Welcome home HackRF Jawbreaker 305, welcome home!

To get the HackRF Jawbreaker running I:

  • Installed Ubuntu 12.04 in VMWare Fusion
  • Ran apt-get update and apt-get upgrade
  • Ran the amazing build-gnuradio script
  • Followed the instructions on the HackRF beta page to build the hack-rf tools and upgrade the firmware

The first couple times I attempted to run the build-gnuradio script it failed. This was due to a lack of ram. My VM was provisioned with 1GB of ram and 1GB of swap out of the box. Bumping it to 4GB or ram (I imagine 2 would have done it) got everything building correctly.

HackRF Jawbreaker

My Jawbreaker shipped today!

Michael Ossmann created the HackRF Jawbreaker a Software Defined Radio capable of receiving and transmitting from 30 MHz to 6 GHz. He gave away his production run of Jawbreakers (funded by the US Cyber Fast Track program) and I was lucky enough to get in on the deal.

When the unit arrives I am hoping to use it to take a closer look at some of the wireless RC gear I have been playing with of late.