An attempted rebuild Posted:
Since only the fuselage of the AXN floater was mashed in the crash, and the wings were still ok, I decided to try and rebuild the plane as a "stick".
Building it was fun: Lots of work with cable-ties and hot-glue, the wings are held together with a plywood sandwich and attached to the stick with rubber bands.
I had to resolder the ESC-to-motor wires to reverse the motor from push to pull, and even though the receiver antenna is completely missing, it seems to get an adequate range.
Unfortunately, I think the end result was a bit too heavy and unbalanced and flying it didn't go so well.
The first attempt was abandonded due to wind before something went too wrong, and on the second attempt it nose-dived into the ground shortly after launch. The result was a broken prop and busted bit of plywood that was keeping the wing level and straight. At that point, I decided to give it a miss move on with a new model and the quad-copter.
Stitching aerial photos - Autopano Posted:
A pretty impressive 360 degree aerial panorama, 1.8 giga pixels of it!
Looks like something similar should be possible with Hugin: http://hugin.sourceforge.net/tutorials/Mosaic-mode/en.shtml
DIY Drones podcast Posted:
I've started listening to this a bit late, probably should have been following along for a while now, it's inspiring and informative.
To err is human, to really screw up requires a computer Posted:
Or an autopilot in this case. Something went wrong with the ArduPilot and the AXN Floater dived into the ground from about 50m up.
First, some nice photos from the day, which had perfect flying conditions:
And a video of a couple of ArduPilot stabilised glides down from about 170m. The glide ratio is about 10%, covering 1200-1500m.
Altitude profile of the last flight:
Overall, the AXN Floater was a great plane, I flew it for 2 months getting about 26 sessions and 7 hours of logged flight time. It took about 1 hour of flying over 5 sessions to learn as I was starting from nothing and didn't have anyone to show me the ropes (a bit stupid really, but the plane survived a couple of rebuilds and replaced servos). The eventual battery life was between 15 and 25 minutes (from a 2200mAh 3S LiPo) and it was covering about 15km distance along the ground in a session.
The maximum altitude I flew to was probably about 200m (I logged 183m with the ArduPilot on board) and the cruising speeds were between 30-70km/h on average.
I've no idea what caused the crash, I had some issues while attempting to test the Loiter and RTL modes, but was able to recover from those. At the time of the crash it was flying fairly quickly (throttle nearly wide open) and there was a bit of a wobble/turbulence, then it just turned and dived:
The fuselage was very damaged, broken in a few places including the motor pod, but the wings are salvagable. The main thing stopping me bothering to repair it (for now) is that the receiver antenna was cut (even though I hot-glued it), and since it's a coaxial cable, it's going to be pretty impossible to repair and still guarantee a decent range.
The ArduPilot was protected well by it's pod, though the GPS socket was ripped from the ArduPilot board. Thankfully there are through-the-board holes I can solder it back on to later.
Time to get serious with the QuadCopter now!
Festo SmartBird Posted:
Pretty awesome really. Other videos gave the impression it was closer to life-size, it's got a 2m wingspan!
Adding a stabilising gyro to the AXN Floater Posted:
I thought I'd try adding a gyro to my AXN Floater to provide some el-cheapo stabilisation (when I didn't want the ArduPilot onboard).
I found a heading hold gyro from DealExtreme and hoped it would work (the standard HobbyKing 401B one wasn't in stock). It really does come in a "Lithium Polymer Battery" package and had no instructions, but looking around at similar products on the web gives you the general idea of how to use it.
It's attached with double sided foam tape and hooked up inline on the elevator channel and a control channel so I can switch it on and off mid-flight.
The control channel determines how the gyro behaves:
- "Left" or "negative"
The gyro is in rate mode. It will dampen wobbles and slowly adjust to the new roll angle (i think the delay pot controls how fast this happens) - "Center" or "zero"
The gyro is off and has no effect. - "Right" or "positive"
Heading hold mode, generally used by helicopters and not what is normally recommended for use in planes. This doesn't really seem to be a problem, when you let go of the elevator stick it will hold the current roll angle, rather than levelling itself back out. This is quite easy to get used to when flying as it's basically what the plane will do without the gyro but it does mean it handles differently to how the ArduPilot stabilisation mode works, which is to "magically" right the plane and keep it flying straight and level when you let go of the sticks.
To set this up on the Turnigy 9X transmitter, I did the following:
- Go to [AUX-CH] and set CH5 to THRO HOLD (this is the switch on the back left of the transmitter and will be used to switch the gyro on/off)
- Go to [PROG.MIX] and set up MIX1 as follows:
State: ACT
Master: GYR
Slave: FLP
Offset: 000
Uprate: 000
Dnrate: 075 (This is the gain, you can tweak this to make it more or less sensitive)
Sw: NOR - The above is for "heading hold" mode, for "rate" mode, change
use the values below instead:
Uprate: -075
Dnrate: 000 - Plug the gyro control plug into CH6 on the receiver.
The above is a bit random, FLP probably should be the master and GYR the slave, but that didn't work for some reason, and ideally you'd use one of the pots to adjust the gain. Using the PIT TRIM directly to control the gain works, but doesn't allow you to quickly find the zero position and switch the gyro off if you need to, so I went with the switch option instead. Someday I may try and program this into the 3 position switch so it had off/rate/heading hold modes.
I haven't flown with it in the wind yet, but expect it should work and it's certainly a cheap and easy experiment.