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Jan 28, 2015, 11:50 PM
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Build Log

X-UAV Talon Build


I'm going to be building up a Talon for a new FPV/Mapping build. This will be similar in function to my Skyhunter, and really just an experiment to see which I like better. I really like the way the Skyhunter flies, in fact, it's my favorite FPV plane so far with large capacity, high efficiency, long range, and stable flight. I'm hoping the Talon can improve on those features with some of its' own:
  • V-Tail: Yaw control (Skyhunter has only AIL/ELE)
  • A more open fuselage
  • Slower landing capability due to wider wing chord
  • Flaperons???
  • Smaller transport size
  • Less setup time
  • Long enough fuselage to hold both Video Tx and R/C Rx

It's a tall order, but from the numerous builds and pictures I've seen, I think it should deliver on most if not all of the above. All parts are ordered, or I have them already. For comparison purposes, I'm using the same power plant as my Skyhunter. Cobra motor, 12x6E prop, running on 4S. The AUW will be similar, and others who've had success with the Talon have used that same motor with good results. I may eventually opt for a 12x8 or 13x6 prop, but for the first few flights I want to do as close to an "apples to apples" comparison as possible between the two air frames.

Planned configuration:
Aileron servos: HS-82MG
Tail servos: Corona 939MG
Motor: Cobra 3520/12 820kv
Prop: 11x8, 12x8, 12x6, 13x6 (will test with different payloads and cruise speeds)
ESC: Turnigy Plush 60A
Battery: 2 x 4S 6600mah Multistar (also have many 5000mah 4S and one 8000mah 4S)
Flight controller: Pixhawk
BEC: Castle 5v 10A - powers the servo rail of the Pixhawk, and also serves as it's backup power should the 3DR power module fail
OSD: MinimOSD
Camera: Sony Effio-V 800TVL 12v
Video Tx: RMRC 800mw 1.3ghz w/ RHCP antenna
Video Rx: RMRC 1.3ghz w/ IBCrazy Crosshair
Radio Rx: DragonLink v2 (PPM/RSSI output to Pixhawk)
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Feb 03, 2015, 12:20 PM
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Airframe is here!


The airframe arrived yesterday from ValueHobby.com. Everything was packed very well and arrived without any damages to the box or the contents. For those of you wondering what version it is, the version I have has a square camera hole in the bottom of the fuselage. It also does not have the FPV camera cutout in front of the landing gear. Overall I'm very impressed with the quick delivery time and really good price from ValueHobby. It seems you get a lot for $100, and I'm tempted to just buy a backup airframe!

I was happy to see that they included two sets of control horns! They have the factory gray ones that simply glue into the pre-molded pockets on the control surfaces. But in addition to these, there were "bolt through" control horns as well. The factory control horns seemed fine to me, when used in combination with plenty of good CA. But it's a nice addition.

It was late when I got started last night, but I made some good progress. I got the main fuse halves glued together, control horns attached, motor mounted, and some components tentatively placed. I'm still undecided on what to do with the nose cone. I'm almost certain I'll destroy it so I'm thinking about not even putting it on. I have some big chunks of foam, and may just build my own solid foam nose cone.

Anyways, here's some pics of the build:


Pixhawk layout (made bottom tray):


(Right) Castle 5v BEC powers Pixhawk servo rail
(Left) MinimOSD
(Bottom) Voltage Reg set to 12v to power Video Tx and Sony Effio-V FPV camera


2x Multistar 4S 6600mah fit fine, and lots more room in here!


Bottom of 800mw 1.3ghz VTx, inline with air intake hole for cooling:
Last edited by TwoHeadsBrewing; Feb 03, 2015 at 12:26 PM.
Feb 03, 2015, 12:36 PM
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Next steps for the build:

1. Bind and install DragonLink micro Rx (will be in rear of fuselage)
2. Build foam nose cone
3. Install FPV camera
4. Wing/tail servo centering and control rod placement
5. Power up and configure v-tail
Feb 03, 2015, 03:48 PM
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Looks to be very professional so far.

Quote:
Originally Posted by TwoHeadsBrewing
Next steps for the build:

1. Bind and install DragonLink micro Rx (will be in rear of fuselage)
2. Build foam nose cone
3. Install FPV camera
4. Wing/tail servo centering and control rod placement
5. Power up and configure v-tail
Feb 03, 2015, 09:15 PM
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Looking good man!
Feb 03, 2015, 09:32 PM
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Thanks! More progress...

Feb 04, 2015, 12:46 AM
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All ready for the maiden tomorrow. V-tail configured and checked in Mission Planner, and verified that it works in both manual and auto pilot modes.



It's an ugly nose, but removable! I need to get a nicer one made at some point.




Tons of room inside under the flight controller deck for ???
Feb 04, 2015, 04:35 AM
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I would make one change before you do to much flying with the autopilot. I don't think flying will be a problem but the position of you pitot tube leads way to an erroneous reading because of the curb you have on the nose. If you had it on the other side it still would be off a little but not as much as the way it is now. In front is actually the best but not always doable but it is very important if you going to do any out of site flying that you have you pitot tube in clean air and pointed directly into the airflow. GPS only tells you if your moving relative to the ground, the pitot tube tells you how fast the airflow over the plane is going.

P.S. First and best option put it in the nose, if not, put it on the other side a few more inches back from where it is now, this gives a more stable flow but still not super accurate.

Quote:
Originally Posted by TwoHeadsBrewing
All ready for the maiden tomorrow. V-tail configured and checked in Mission Planner, and verified that it works in both manual and auto pilot modes.
Last edited by qbert55ca; Feb 04, 2015 at 04:40 AM. Reason: more info
Feb 04, 2015, 12:57 PM
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Thanks for the input, and the location of the pitot tube is definitely a concern. I'm going to see how it reads today when I fly it. If I get weird readings then I will reposition.
Feb 04, 2015, 02:08 PM
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Your airspeed will very seldom be what you GPS speed except on a very calm day. The best way to calibrate the pitot is to point it into a wind and check it against an anemometer.

Quote:
Originally Posted by TwoHeadsBrewing
Thanks for the input, and the location of the pitot tube is definitely a concern. I'm going to see how it reads today when I fly it. If I get weird readings then I will reposition.
Feb 04, 2015, 02:15 PM
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Today is actually pretty calm, so it will be a good time to test it. I had the pitot tube mounted in a similar spot on my Skyhunter, but it was a bit more forward and the nose was more rounded. I'll see how it goes today and make adjustments if necessary.

Skyhunter pitot:
Feb 04, 2015, 06:05 PM
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Maiden was a success. I had a minor mishap on the second landing with my DragonLink oddly kicking into failsafe mode. So it nosed in a little bit, but no visible damage to the plane or any components. But the Falcon flew incredibly well, and with the Pixhawk is just a piece of cake to fly. Nice glide slope despite having 13,200mah of battery on there, and still handled well at >70mph.

With mixed flying speeds, I'm consuming about 216mah / mile. With 13.2Ah that should give me a theoretical range of just over 61 miles. That is way over my maximum of 14 miles, so it's clear that I need to get working on my video range.

Maiden flight summary:


I was flying LOS at this point, so never saw the Low RSSI warning, or that RTL had been engaged. Obvious failsafe, although I'm still not sure why. It may be a moot point, since my DragonLink V2 came in today. Next flight will be on the v2!
Last edited by TwoHeadsBrewing; Feb 04, 2015 at 06:10 PM.
Feb 04, 2015, 06:51 PM
Snipe the Skies!
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Wow, very cool man!
Feb 04, 2015, 10:12 PM
Fight for the Right to FPV!!!
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Absolute blast watching "THBrewing's" maiden today! First time up and he flew the Talon like a pro! I think his plane might have some arial mapping in it's future and it was cool to see him already up there executing some very impressive looking coordinated turns and getting his AP dialed. Hope we can get our video feeds to "play nice" so we can try some tandem flights with the Talon's down the road sometime!!
Feb 05, 2015, 11:46 AM
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Thanks melsailsnorth! It was great to get it up in the air and see how it handles. I'm super impressed about with the stability and efficiency of this plane. Looking forward to working on the video system and getting my crosshair up and running.
Feb 05, 2015, 04:23 PM
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Nice build! Maybe off topic but about the pixhawk, can the auto tune function in pixhawk be used for fixed wing aircrafts as well and how many model memories does it have?
Feb 05, 2015, 06:53 PM
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The Auto Tune feature does work with fixed wing, although I have not used it. I've only used it on my quad, with sporadic results. I think it was related to a bad build of the firmware that went out right before I used it, but I never ended up running it again. Just gave myself a crash course in tuning PID's and started messing around.

As for model memory, the Pixhawk only "remembers" one at a time. You load the Pixhawk up with the appropriate firmware for your aircraft (plane, quad, tri-copter, quad, octo, etc.). Then you run through the initial setup wizards and do any customization you want to do. From within Mission Planner, you do have the ability to "Save Parameters" which essentially saves your model to the hard drive on your computer. Once I've got my aircraft dialed in, I always save off a copy of my parameters. You can then easily do a restore at a later date by opening the saved file in Mission Planner, then writing the parameters to the Pixhawk.
Feb 05, 2015, 08:47 PM
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I used the Autotune feature for my Phantom flying wing (and Pixhawk) with great results. I've not had to touch anything since and she flies great in FBW-A, stabilize and return to launch. I would like to get "cruise mode" flying proper but to looks like that will take some manual tweaking . I found that you need at least Level 7 auto tuning, otherwise it's not quite aggressive enough (at least for that airframe). It was a welcome feature, though, as tuning PID's is not something I"m very good at yet.
Feb 06, 2015, 02:28 PM
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Sounds great, what kind of rc shutter do you plan to use for mapping? I haven't decided on any camera yet but I figure I might have to build a servo rig if there is no other suitable solution available.
Feb 06, 2015, 03:02 PM
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I have a USB trigger, and run CHDK on my Canon SX260. I usually just run an intervalometer script, but that's been problematic with trying to geo-tag the images. If you know exactly when each picture was taken (via the Pixhawk log), you can match up the pictures with the GPS data.

Here's the guide I used: http://copter.ardupilot.com/wiki/com...trol-tutorial/

The only problem with the Pixhawk is that it triggers using 3.3v. The Canon need 5v, so you need a step-up board like this: https://www.sparkfun.com/products/10968
Feb 06, 2015, 03:41 PM
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You got it all figured out! I was thinking of getting the canon g7x simple because it is a great camera but at the moment it wont work with CHDK, so maybe I will also get a cheap second hand older canon that works with CHDK as I imagine the picture quality wont matter that much for mapping.
Feb 06, 2015, 04:05 PM
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Just another note on the 3.3v coming from the Pixhawk. I thought I would need a step-up 5v on the USB trigger, but since I'm powering the servo rail with 5v, I did NOT need it.

Here's a bit more detail on my Pixhawk testing with the USB trigger:
  • Trigger connected to RC 7 on Pixhawk
  • On transmitter, bind Channel 7 to two position switch (mine is Gear)
  • Pixhawk parameter RC7_FUNCTION = "1" (this means RC pass through)
  • CAM_DURATION = 10
  • CAM_SERVO_OFF = 1100 (Shutter OFF)
  • CAM_SERVO_ON = 1900 (Shutter ON)
  • CAM_TRIGG_DIST = 0
  • CAM_TRIGG_TYPE = 0
  • Connect to camera loaded with CHDK script
  • Power on camera and load CHDK
  • Choose "Enable Remote" in "Remote Parameters" menu
  • Toggle Gear switch to test taking the shutter release

When you're ready to fly and have Pixhawk automatically trigger your camera, you need to change the RC7_FUNCTION = "0" (This lets the Autopilot trigger the camera).

In your mission planner "Survey Grid Tool", set your camera config:
Trigger Method: CAM_TRIG_DIST
Servo: 7 (or whatever channel you have configured)
PWM: 1900 (this sends the "Shutter ON" command)
Cycle time: 2

Last edited by TwoHeadsBrewing; Feb 06, 2015 at 04:12 PM.
Feb 06, 2015, 05:06 PM
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This is very helpful, thanks! Just feels like I have intruded on your thread though, sorry for that.
Feb 06, 2015, 07:23 PM
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No worries, I'm not a thread nazi! I'm happy to share what I've learned, especially since most of that knowledge I've gained here on RCG and other forums.
Feb 09, 2015, 04:10 PM
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Here's a quick video my dad put together. Unfortunately, my Mobius files are corrupted somehow and I can't get them loaded into an editor.

Talon Maiden (1 min 57 sec)


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