Given the popularity of the 230/250 quads at the moment (blackout etc), I thought - wouldn't it be cool to have a rig that can do the ground skimming proximity stuff, but also with the normal "mod cons" of the APM?
Traditionally though, an APM would never fit. Until HK released the mini...so I built one.
I started with the Haldey-Bocks 230 frame, in Carbon Fibre. This was a mistake. I should have gone for the 250, because the fitting of the ESC's was a bitch of a job, especially with the thick 3DR power module hanging off it. And naturally, I forgot to solder in the XT for the video feed, so had to start again...
Anyway, this is the bare airframe:
So onto the fun part...
First, I fitted the camera, so I could make sure the clearances were good. I mounted it directly to the front CF plate to make sure I had as much room as possible behind it.
Second, I mounted the GPS antenna pole. This required a lot of trial and error, but eventually I found a position which worked.
Third, I fitted the APM mini in front of the post, and behind the camera. There is *just* enough room to do this. It is currently mounted with double 3M pads - I will review vibe damping after the first flight. Supposedly the blue balls do the "clean/dirty" thing, but is it enough to keep the APM within Z axis tolerances? Time will tell. These rcx are not the smoothest I have to say, and a propless spin up was really vibey.
I wired in the GPS, and the radio.
Then I mounted the 3DR telemetry radio to the roof. It is likely I will replace this with a minimOSD, and run a really simple OSD - volts, ground speed and home distance.
I then cable-tied the xt60 back on on itself on the PM - it was interfering with the props.
CoG is spot on, even though I thought it would be rearward.
Weight with tx will be 505 grams as you see it here. I have a wiring exercise to do (shorten and tidy), and to enclose the APM with some foam (for the Baro), and I hope that brings it down below the target 500 grams.
And that's it! It all fits together nicely. All the normal calibrations done - just compassmot to do (want to wait until I've got the camera and tx wired in first). Going for a really small 200mW 32ch 5.8. Will fit perfectly.
I didn't have time to get the thing in the air, but should able to get it in the air at the weekend. Can't wait to use DRIFT on this...:-)
Comments
@Euan: Like Gary M. I can't find this frame maker. You have it as "Haldey" in your original post and "Hadley" in your response to Gary ... Facebook search yields neither. Can you provide a link to his page? Thanks.
@Euan: Super!
Buried somewhere here is a post showing how to dynamically balance motors, using a zip tie around the circumference. You might want to hunt that up, the only way will probably be via a Google site search, there not being a usable local search engine on this crap forum software.
Small is the direction we're headed, some will kick and scream and there won't be as much money to be made selling hardware but I predict that within a couple of years a sub-one-pound quad will have all of the capabilities, including stability in wind and such as today's much bigger vehicles. I myself have retired my old big Hex and am now getting better results with a Flip-frame/Pixhawk quad half the size. And once we're down around a half-pound anybody attempting regulations/certifications is going to look really, really foolish.
I had an APM2.0 in a 300mm frame and it was perfect. At first i had a hard time making it just fly, but you just need to lower your PIDs like A LOT! once I realize that, it flew like a charm
Jiro,
I built the X230 as a test frame for Arducopter and it handles it perfectly well. There is no reason you can't get performance equal to any other controller with the correct tuning.
@euan
The kyosho green vibration gel is much nicer than moon gel and for me does a nicer job. Moongel is too sticky and for me rolled up, the kyosho stuff is much nicer and easier to cut and work with.
I don't think the size of the controller itself is the main issue - yes, it will affect CoG, weight etc, but it won't affect response rates.
How well the quad flies depends what "resolution" the controller can control the PID loop at, and whether the airframe is solid enough to ensure that the controller is able to get input=output messages. This usually means ensuring the arms are solid, and the motors are not moving around too much in all 3 axis.
Smaller airframes don't have a lot of material between the motors and the controllers, so less vibrations are absorbed. This will affect controller accuracy as well.
If anything, the rate limiting step are the ESC's - normally these use very small motors and small props, spinning extremely fast. This might be why these tend to fly better with SimonK ESC's (I stayed with standard ESC's for the moment).
@Euan, I had some bad experience with APM2.0 on compact Quad. Several trials gives no good result.
And I heard good things for OpenPilot CC3D on small Quad as well. Those are the reason of sceptically of APM( large foot print) for small Quad. However, you chose HK compact APM clone that may provide good result.
I assume small air frame requires small flight controller. What do you think ?
Coming at the weekend Mustafa! Will run the compassmot test tonight, and maybe an "up and down" maiden, if I have time.
Test flight please:)
" two 3m foam pads" <- Yes that should keep it vibration free...(8-)
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