I started this project back in September with FPV flying in mind but have step-by-step working into making it a full UAV.

My build covers photos from the construction process and components I decided to include. As of this point in time my Skywalker platform contains the following UAV-FPV components:

• Ardupilot 2.5 mega
• minim OSD
• 915 Mhz 3DR telemetry unit w/stock antenna
• 600 mW 5.8 Ghz immersion RC video transmitter w/ spiroNet antenna
• EzUHF diversity receiver w/stock antennas
• GoPro Hero 2

Ground station components:

• FatShark predator video goggles
• 3DR telemetry
• ASUS K55N-DS81 Notebook
• computer joystick
• Turnigy 9X w/ EzUHF tranmitter and Diamond SRH771
• pan/tilt AT mount w/ maestro servo controller

The electronics package includes:

• Turnigy 3536/8 1000kv outrunner w/ 9x6 APC pusher prop
• Hobby King 60amp ESC
• Ready Made RC 5-7.5A UBEC
• HXT 9 gram servos for ailerons, elevator, rudder, and pan/tilt on camera, possibly add flaps later
• Turnigy 4500 nanotech 4s lipo for flight and UAV components (nearly every setup I've seen has independent flight batteries and VTX batteries, but i'd like to keep things as simple as possible. Maybe i'm doing it wrong...)

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Background

To start the project I purchased a v5 Skywalker airframe and used the HXT 9 grams and hobbyking 30 ESC i had from another plane. The pan/tilt mechanism I purchased from readymadeRC.com which has a great selection of parts for common FPV platforms (skywalker, bixler, etc.)I bought the 5.8 Ghz transmitter and FatShark predator video goggles from Hobby King along with the motor for the plane.

I have not yet flown the air frame, and I know it's not a good idea to start out complex on any system (KISS). I have, however, had some experience with FPV. I used the same goggles, GoPro, and video transmitter on a friends plane, and ANX clouds fly, with great results. Range of the video system seemed to far exceed that of the Spektrum dx6i I used from my few testing flights around my local field. I must say that flying FPV for the first time was an amazing experience! My first FPV flight was from hand launch all the way to landing. I had originally thought that I'd lose my sense of depth making landings a challenge but from my experience that wasn't at all a problem.

I know this project will be a very long process with a steep learning curve, but I do not intend on rushing anything. Hopefully my previous experience with FPV and remote control aircraft in general will help me along in this adventure.

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2/26/2013 Update

The airframe has been upgraded w/ landing gear and a new paint job as well as a new wing mount method and a GPS hard point mount. Ardupilot, telemetry, OSD, and current senors have all been connected and configured and ardupilot loaded with the skywalker parameters.

I am currently working on connecting the Turnigy 9X witht the EzUHF system which requires the 9X to be updated to a higher PPM frame rate. The default framerate of the 9X is 20.5 I believe, but dont quote me on that. The EzUHF requires at least 22, or maybe it's 22.5. In any case, the er9X firmware has an adjustable PPM. The firmware upgrade uses er9X open source. I will document my firmware upgrade when the hardware components of the 9X build arrive in the mail!

Thinking about a similar Ardupilot setup for my X8, will keep an eye on this project.

I'm now in the middle of the soldering for the firmware upgrade. It's a pretty straight forward deal thanks to this video i found while surfing the web.

er9x Turnigy Flash Radio Control Upgrade from beginning to end! Firmware soldering eePe etc (20 min 18 sec)

Extremely helpful!

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3/5/2913 Update

I finally got the 9X flashed w/ the er9X firmware! The update was pretty straight forward but i did run into a few minor problems along the way, starting with the USBasp board. While attempting to flash the firmware to the 9X i was prompted with an error saying that AVRDUDE reported a connection fault with the TX. A quick search on the web revealed that a resistor pack (R8) on the USBasp board was to blame. Apparently some USBasp boards come with 100 ohm resistor packs and can work, but mine came with a 200 ohm pack and thus reported this error. The fix involved simply removing the resistor pack and putting jumper wires between the connection points. My only note on this was that some VERY precise soldering was needed.

After the soldering was finished the firmware update went flawlessly. My second minor problem I encountered was getting channels 5-8 to work on the er9X. I didn't realize that they were not activated on the transmitter but soon found the mixing menu and the rest was pretty straight forward.

So as of now, I've got my ground station communicating via 3DR telemetry to APM, have the fail safes set for APM (both GCS and RX fail safes), Skywalker parameters loaded, level set, control surfaces and ESC calibrated and have the 3 position switch on the transmitter set to "manual", "stabilize", and "RTL", and finally i have my OSD functioning (but it still need minor adjustments as some data overlaps the data the GoPro sends out). I did encouter one thing that needs to be looked at a bit further; my elevator servo seems to be glitching/chattering even under no load. I'm not sure if its the UHF/APM system (which is strange because the other servos seem fine) or if the servo simply needs to be replaced due to a bad pot. in any case, I will be running a "diagnostic" to see what the problem is.

I am rapidly approaching first test flight of the APM system but will be double, and triple checking all components and reading as much material on the APM as I can beforehand.

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Update 3/12/2013

Got some small goodies in from hobby king yesterday including canopy latches and servo wire extensions. I rigged up a neat little latch for the skywalker access door using a canopy latch and a piece of bass wood.

I have also determined the cause of the elevator servo glitch. The 3DR telemetry unit was interfering the servo wire. To solve the problem I simply moved the 3DR away from the elevator servo wire. I was noticing substantial glitching on the pan tilt servos for the GoPro so I wrapped those servo wires in 2 ferrite rings and the glitching completely stopped.

I have also noticed some glitches in the video 5.8 Ghz video signal so my next step will be making a simple LC filter from a ferrite ring and capacitor.

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Update 4/4/2013

Finished the installation of the patch antenna on my pan tilt ground station as well as set the end points for the servos via the maestro servo controller. I also installed a DC power filter for the video power lead as i'm using only one flight battery in the plane.

I have also started working on flaps. I figured I had the necessary components so I might as well add them.

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Update 4/27/2013

Well, after months building and preparation the skywalker finally took to the air this morning! Everything worked perfectly, from manual to stabilize, to RTL, and even down to the video overlay from my ground station to mission planner! I just flew low altitude LOS today as I didn't have a spotter.

I placed my CG at about 5mm aft of the servo line. The plane flew great, with no bad tendencies, but it did feel slightly nose heavy. For now I will keep the CG but may experiment with moving it back further in the future to get that "floaty" feeling everyone looks for in FPV.

I have some ground photos of the plane and ground station and will work on uploading the GoPro video later.

I almost forgot to mention, but i was having some last minute qualms about using only one wing bolt on the forward part of the wing mount system, so I redesigned the mount for 2 bolts up front. wing feels much sturdier now.

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Update 5/2/2013

So finally had a chance to look though the first flight data from last Saturday. Telemetry link seemed pretty good at about 75-80% signal strength. I posted a photo of my first flight, which was all very close in flying. my second flight, which I have yet to look though ranged about 0.85 km from home.

Today I ran a RF analysis with the Immersion RC tool for the ezUHF system. The bottom panel shows the receiver on by itself, and the top panel shows the receiver and transmitter on. I'm not really sure what this data means, so I'll be poking around the forums to find out. The test was performed inside my house next to my laptop and cellphone. the GoPro 2 being on or off did not change the baseline RF signal no matter the distance or orientation of the camera to the receiver.

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Update 5/5/2013

On my friend's request I took the UAV out again today to give a little demonstration. It was pretty overcast today and the GPS signal was intermittent at best. the mavlink also thought the plane was about 1/2 mile away from it's actual location (again, GPS problem).

The plane flew great, and even w/ the GPS acting up RTL still worked great! (although the plane flew to the home location but continued heading south without going into loiter) I let my friend use the goggles and pan/tilt around a bit.

Video of the few flights today is compiled in the video.

Homemade UAV (4 min 1 sec)

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Update 5/6/2013

The GPS was again causing problems today and deciding to not lock with any satellites while indoors. I've not had a problem with this before, but for some reason I had to take my entire setup onto my front patio in order to get a satellite lock. Even then, the lock was to 6 satellites and it was off by about 50 meters. Hopefully i can figure out how to avoid this problem for future flights. It could be entirely possible that my Vtx or UHFrx are interfering w/ the GPS unit.