RCT800 Takes a bath!

It was a beautiful day and a perfect time to make some aerial videos on a sweet marshy part of the Holland River. I wish I had taken some pictures to document the crash but at the time I couldn’t manage it because I was frantically running in a panic! The only real pictures I had of this event are in the Holland River somewhere.

About 2 minutes into a controlled flight my RCT800 became completely uncontrollable (stable mode) and stopped responding properly… while drifting away!! In a panic I threw the RTH (return to home) switch hoping that this function might be able to control the craft when I could not. This caused the RCT800 to start dive bombing the ground before flying up again (like giant Us in the sky). I stood there watching with a feeling of helplessness (and a little horror) for about a minute or 2 until the crash. Anyway, the Holland River really isn’t that big or wide in this area but this was (of course) exactly where my RCT800 ended it’s crazy flight… in the river with a giant splash! You can’t see the river from where I was standing but I saw the splash well enough and started running!! The RCT800 was in the River on the opposite bank from me and 100s of meters away! When I got to the craft some of the props were actually still spinning (slowly) underwater!!

Lost:

  • My Cannon Digital Elf – somewhere in the Holland River by Rogers Reservoir Newmarket. This isn’t a scary river at all but on the day in question it had a good current going and there is a nearby waterfall. Decided not to push my luck too much in the River and couldn’t find the camera from shore when it became detached from its mount.
  • My flip-flops!! There is a mud flat leading up to the River and as I ran for my craft I literally sank up to my thighs in some spots… alas my flippy floppies were claimed by the river bank!!

Damaged:

So far my tests indicate that I’ve got 4 blown ESCs.  I bought the DJI 30amp Opto ESCs so this was an expensive crash (around $80) but given what else might have failed I am pretty lucky. I have yet to receive my replacement parts (ordered) but I should be back up and running with this craft soon. I had also made landing gear extensions from wood; these were completely smashed by the crash but they were cheap and home made so not a big deal!

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The Cause:

It’s a little difficult to know exactly what went wrong when you retrieve your partially smashed helicopter from a river but I did notice one important point;  the GPS mount is made from a fibrous material and the pole seemed a little compromised and bent at one end. It’s not clear if this was from the crash in the river or a prior incident but I think this could have caused the antennae to bend mid flight. This would have caused problems for ALL the flight modes I used while trying to recover the RCT800. Ironically, I did not try full manual mode because I thought it would make things worse and this mode may not have been affected by a bent GPS. You can see the frayed material in this shot.  The next version will NOT use an antenna and the GPS sensor will be mounted flat on the airframe to prevent a recurrence. Also, if something like this happens in the future I will definitely be going for a controlled crash if the auto pilot modes don’t work. In hindsight, I let the craft hang in the air for too long when I still had throttle control and could have put it down (crashed) more quickly. The results may have been the same but hitting the river was a complete fluke!

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It’s really not much consolation but at some point everyone crashes. This makes safety and aircraft maintenance a paramount concern. If my little crash had happened in a busy area it would have been terrifying and dangerous! Anyway, as it turns out no one has more experience crashing UAVs than NASA (they’ve been doing it since the 60s). A little while back they released an e-book about it… It’s called Crash Course and dissects quite a few of their UAV crashes. Cool toys and expensive crashes these guys have!

RCT800 Parts List – actual parts used

Having recently built an RCT800 Hexacopter from parts I have a pretty good idea of what is needed to build a Multicopter and how the parts all fit together. Check out my UAV General Parts List if you are interested in a general description of the parts you’ll need.

There are literally thousands of ways to build a Multicopter now and the list of available parts and websites can be a little daunting. It’s a good idea to start out with a purpose and or goal in mind and then build your list before buying anything.  This can help you develop your desired parts list in a way to ensure success. This also lets you enter your craft specs into an online calculator tool like the XcopterCalc calculator which will point out any problems you might have and estimate your flight times.

Heli Part Purpose Pcs
Naza Flight Controller and GPS Flight Controller 1
RCT800 Airframe 1
HP4215 630KV 24N18P Multicopter Brushless Motor Motors 6
DJI Opto 30 ESC ESC 6
13×6.5″ Carbon Fiber CW CCW Propellers (6pcs) Props 1
DJT – FrSky DF 2.4Ghz Combo Pack for JR Receiver 1
ZIPPY Compact 3700mAh 3S 35C Lipo Pack Battery 1
Various LEDs Lighting and Orientation – Blue, Red, Green 1
Turnigy Receiver Switch LED switch 2
Not on board Heli
Turnigy 9XR Transmitter Mode 2 Transmitter 1
DJT – FrSky DF 2.4Ghz Combo Pack for JR Trasmitter Module 1
Turnigy 9xr Battery Transmitter Battery 1
ZIPPY Compact 3700mAh 3S 35C Lipo Pack Backup Battery 1
B6AC – IMAX B6-AC Charger/Discharger 1-6 Cells Charger 1
Wires Wires 1
Connectors Connectors 3.5 bullet 6
Connectors XT90 connectors for battery 6
Parallel Battery Wiring Harness- build or buy allows two batteries to be used at once 1

**the list above produces a Hexacopter with great flight control and performance characteristics however I am not necessarily recommending these parts. This was a relatively expensive build and some parts such as the RC Timer 630KV motors have performed a little more poorly than expected (these motors have great performance but terrible prop mounts which introduce vibration into your aircraft).

1SQ Quadcopter Repair

Every once in a while even the toughest fighter gets beaten. That’s kind of how I feel about my 1SQ. I broke it last week but in reality it had no right to be working anyway after taking the amount of (accidental) abuse it has seen. This has been a great little toy/trainer but it finally gave in last week and needed a little TLC.

This seemed like a relatively easy fix to begin with, the battery wire had become compromised/frayed over time and finally stopped working altogether. Simple right… just solder on a new wire and connector!!?? Anyway, after removing the board from the aircraft I started to remove the battery wire and the “gunk” they insulate the connection with. During this process I accidentally knocked an adjacent resistor off the board too (the little brown thing). This isn’t looking good, its getting worse!!

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As you can see above, this was now a 3 step fix and one of the soldering jobs looked a little more difficult.

I had to:

  • Remove the old battery leads from the board by heating the solder and pulling the leads out (already completed in the above picture).
  • Reattach the resistor I broke off (this one looked a little scary because the contacts were so small and my thumbs are huge). Pretty sure a machine soldered this the first time.
  • Reattach the positive and negative battery leads through holes in the board and solder them in place.

Hopefully, you can’t really tell but the end result wasn’t exactly what I intended… If you check it out you can see that I have the resistor on a little sideways (circled in red) and I put the negative lead through from the backside of the board to stay away from the resistor (circled in black). At ant rate, the fix works and seems solid so I decided to leave it.

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Plugged the battery in and everything started working like a charm! **Actually I plugged in the motors wrong to begin with and all my Quad would do is flips… If you have the same behaviour you may want to check your motor connections.  The picture below is correct and can be used as a wiring reference:

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