Blogs

Basically, I thought I'd blog my latest build, to see if it offers the community any helpful ideas.

I approached this build with a couple of objectives - to build a test bed for arducopter features and new releases, to clear down some of the parts bin and older parts.

Now a parts bin special is nothing fancy, but there are a few important considerations:

- vibrations. It's very likely your will build it using old props, old motors, and an old frame. Likely these have all been crashed at some point. That's why they were in the parts bin, admit it...;-) All of these will vibrate. So it's important you pay more attention to vibrations than normal. Your design should emphasise this

- design. Just because you have 4 motors, four props and 4 ESC's does not mean it will fly. ecalc.ch is your friend, as always. Don't spent nights building it, and finding out won't fly

- compatibility. Last time this airframe was probably in the air, arducopter ran on a single 1280. Well, it doesn't anymore.

So what did I do?

1. Airframe

- Measured all the M2.5 bolts and nuts. I chucked any that were bent or rounded. If this frame has been apart in the past, some of the holes will be slack. All frame bolts now use loctite to compensate for their age and the likely higher vibe levels.

- Double checked alignment. As it was, I needed to bend Motor 4 slightly.

- As always I labelled everything...motor number, rotation, arm number, servo leads all numbered. Frame is also marked with my contact details.

- I added some jdrones anti-vibration mounts. My 2216-11's aren't the smoothest anymore, so I start vibration mitigation here.

- I like to cable tie behind both joins of the motor bullets, and keep the bullets visible for preflight checks. These are more important now, because the increased vibes will shake stuff loose.

- I re-balanced the props. Just in case.

- I used 4 very strong rubber risers to insulate the landing legs from the frame. This is a slight modifier on the "Clean / Dirty frame" design used by others. I also used the anti-slip rubber matt from the car (used to stop your phone slipping around) to stop the battery moving around, and to providing yet more damping. That's an 11,000 3S maxamps.

- The legs needed to have washers added on the inside of the cross members to stop them wobbling. This is important, because movement of the compass during compassmot could be misinterpreted.

2. Electronics - All normal good designs apply here, starting with vibes. 

- I started with the APM case; the APM board now sits on top of the rubber washers. I have no idea if this will have any effect, but it should all add up

- The whole electronics stack is mounted on 4 rubber risers, and the APM will get a 3D printed vibration plate from shapeways soon (currently sitting on moongel). I have this mount on my workhorse, and it's a good un'. 3DR APM is original but compass trace now cut, the telem is a chinese knock off, and the Orangerx is junk, but maybe the 2 sats that are coming from HK will improve matters.. Not in shot - strong black tape not on all my rx sat connectors, following Saturday crash (which was partly caused by sat connectors coming loose). Rx and Telem boards mounted on 3M anti-vibe double-sided blocks.

- GPS is a 2.5 unit, and the compass is from china. Both are mounted on a DJI style post, drilled and bolted into the top plate of the frame. I have extended the cables using aftermarket ones, to keep the routing tidy. Can't quite see it, but there's a tiny rubber square between the GPS and the compass. Again, vibes...Post definitely works. This is the compassmot score ;-)

Note 3DR....PLEASE PLEASE PLEASE make 30-45cm version of the ridiculous 5/6 cable please, so I can route it all neatly!!!!

And lastly, I pulled together an old gimbal, just for the sake of it, on a "old" martinez. :-)

Any question on how to revive an old airframe for modern use, let me know.

And to sign off, how is it? Well, I'm going to run autotune on Saturday and find out!