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Members => Build Threads => Topic started by: HerkyBird on February 28, 2015, 01:07:40 PM

Title: Brushless Carbon Micro-H Quad Build
Post by: HerkyBird on February 28, 2015, 01:07:40 PM
I started this project back before Christmas but due to a number of issues along the way it's been rather delayed but it's finished now so I thought I would do a write-up here as there seems to be very little on here related to micro-quads.

This project started out with me seeing the various micro/nano style microquads that were around and being repeatedly tempted by the original non-FPV Blade Nano QX and then the FPV one. I resisted the temptation to get one as a few years back I swore never to buy another brushed motor model so I held out for a commercial brushless model but gave up waiting.

This is a 'warts and all' write-up including my problems along the way as I hope anyone else interested can learn from my experiences as this is still an immature area of the hobby. The good news is I got to a very satisfactory end point but will offer some insight on further improvements I have in mind.

I wanted to build a micro sized quad for indoor/small field use that weighed less than 100g, was powered by brushless motors and was fully FPV capable. There was one brushless model on the market called a 'Super-X (http://www.overskyrc.com/superx-micro-brushless-quadcopter-p-507.html)' but it was only powered by 1s and was LOS only. Reports indicated that although it flew OK, it wasn't exactly over-powered so if I added FPV gear I felt it would get too heavy and hence sluggish. To overcome this I decided to stick with similar dimensions (135mm) but move up to a 2s drive system. This is where it started to get fun as there wasn't anything really 'off the shelf' so I set about identifying the components to use. I started off thinking of a build around the Spektrum VA1100 camera/vtx (http://www.rcgroups.com/forums/showthread.php?t=2287035) but decided I could do better with individual components and do a custom build so this is what I initially chose and ordered up:
...and here is what all the components looked like by the time they arrived.

(http://s7.postimg.org/9cs949ql3/Components.jpg) (http://postimg.org/image/9cs949ql3/)

Before I even started building I stumbled across the AfroMini 32 (http://abusemark.com/store/index.php?main_page=product_info&products_id=45) which I had missed previously so I decided to order one up as I am already flying Naze32 boards and wanted to stick to a consistent F/C & UI for configuring.

The first challenge with the build was to decide how to mount the motors as the mounts supplied are push-ins for brushed motors.  As you can see below (building from left to right), I designed a filler using some scrap plasticard and the fiberglass mounts that came with the motors.

(http://s22.postimg.org/myz11mx4t/IMG_1771.jpg) (http://postimg.org/image/myz11mx4t/)

Unfortunately in the end it turned out the supplied motor mount screws weren't long enough so I went with the center on it's own as that worked fine, I didn't glue them in place straight away though which allowed perfect alignment of the motor cables first before fixing.

(http://s21.postimg.org/szyk45i1v/mount_top.jpg) (http://postimg.org/image/szyk45i1v/)(http://s4.postimg.org/qxh265ll5/Mount_Bottom.jpg) (http://postimg.org/image/qxh265ll5/)

At this point set about adding connectors to the motor leads and this is the bit I hated most as the HK motors are just a single core extension of the enameled windings so very fragile and hard to re-solder when they broke, I even had to take one all the way back to the motor case and replace the leads as it broke off right at the windings (lesson learnt, check motor lead type before ordering!).

Once the motors had connectors on, I set about mounting them onto the frame. I did have a bit of a challenge with the motors as the wires don't exit very flush which meant the motors didn't sit properly ...

(http://s27.postimg.org/bfhti5w4f/Wonky_Motor.jpg) (http://postimg.org/image/bfhti5w4f/)

...so just a little filing was required and all is fine now.

(http://s13.postimg.org/eu5qi9t0z/Filing.jpg) (http://postimg.org/image/eu5qi9t0z/)

Once the AfroMini and connectors arrived I set about mounting the connectors to the FC so the esc's are plug & play. It wasn't as easy as it looked as the hole spacing in both length and width was wrong so had to get creative with bending pins 90 degrees and 'surface mounting' some connections, I wouldn't recommend anyone else try this, it wasn't worth the hassle in the end. After doing that I also added on the Spektrum Sat and soldered that up and it makes for a very compact FC/Rx combination.

(http://s11.postimg.org/u6v9q585b/FC_Sat_top.jpg) (http://postimg.org/image/u6v9q585b/)

Here's the underside of the AfroMini, I added extra wire across the +ve and -ve rails to ensure they could carry the current needed for the motors as this acts as a pdu for the OverSky esc's. One lesson learn the painful way though, FTDI adapters don't like to be plugged in at the same time as the 2s main battery and it emitted some magic smoke, in hindsight, disconnecting the 5v +ve lead from the FTDI adapter would remove the problem as the 7.4v from the 2s battery then can't make it's way back to the FTDI.

(http://s4.postimg.org/ck5p88ozt/FC_Sat_Bottom.jpg) (http://postimg.org/image/ck5p88ozt/)

Next up was to mount the camera and vtx up-front which was fairly straight forward and I added a micro connector to the vtx and plugged it into the F/C for power.

(http://s30.postimg.org/z1oi55kkd/FPV_Gear.jpg) (http://postimg.org/image/z1oi55kkd/)(http://s21.postimg.org/mvu0nj8v7/IMG_1781.jpg) (http://postimg.org/image/mvu0nj8v7/)

...and finally I mounted the esc's,tidied up the wiring and added some light weight 'tie wrap' legs.

(http://s11.postimg.org/gwzfqg6tb/v1_build.jpg) (http://postimg.org/image/gwzfqg6tb/)

...and here's the finished article, 52g without li-po (70-80g with battery depending on capacity).

(http://s4.postimg.org/euzmi1rbd/v1_finished_build.jpg) (http://postimg.org/image/euzmi1rbd/)

Next up was a test flight and it worked! Only had a couple of quick hovers in a confined space to start with but it seems to have plenty of power on a partly charged 2s 450mah lipo but was very twitchy in the vertical plane so needed PID tuning. Unfortunately this is where it started to all go a bit pear shaped on Christmas Eve of all days :(

I charged up the 2s battery fully (I was using partially charged ones before) and the below happened to 2 of my 4 esc's when I powered up :(.

(http://s23.postimg.org/oc2d1zizb/fried_escs.jpg) (http://postimg.org/image/oc2d1zizb/)

As far as I could remember, I hadn't done anything to the build since my last test flight a couple of days before so I was mystified as to what had happened. In the end I dropped an email to Jon at Oversky as I couldn't work out what had happened and he responded very quickly to my email and after speaking to his technical guys confirmed to me (on Christmas Day!) that there was a new design of these now available to address a problem with the first production batch and that he would send me out 4 replacement units straight away! Unfortunately, with patience not being one of my best virtues and not expecting a response until after the holidays, I had immediately placed an order for 4x YEP 7A (http://www.hobbyking.co.uk/hobbyking/store/__37944__Hobbyking_YEP_7A_1_2S_Brushless_Speed_Controller.html) esc's from HK to try instead so I now had 2 sets of esc's on the way.

Once the YEP 7A's arrived I set about replacing the MU-3A's but I just couldn't get the HK motors + YEP 7A + AfroMini working properly together so I quickly contacted Oversky and bought a set of the new Oversky 2s motors and their new Naze based FC/rx from their Hermit model to be delivered with the esc's (neither of which were available when I started the project) and I waited for those and my replacement MU-3A's to arrive. In hindsight I think I could have tried flashing the YEP's with BLHeli as I think that may have helped as that is meant to be better for multicopters and the smaller higher reving outrunners. I haven't decided yet whether to try this or just sell the YEP's, we'll see...

In order to get these motors to fit I had to change my mounting approach slightly as the mounting holes were different but after chasing down some slightly longer M1.2mm screws and using some more plasticard I mounted them more like I initially intended to but with an additional disc on top of the arms to stop the motors falling though.

(http://s13.postimg.org/6wl0kyzzn/New_motor_mount_top.jpg) (http://postimg.org/image/6wl0kyzzn/)(http://s22.postimg.org/z84q6fu4d/New_motor_mount_bottom.jpg) (http://postimg.org/image/z84q6fu4d/)

These motors seem much better quality than the HK motors, if maybe ever so slightly less powerful but they are lighter and the motor leads are so much easier to work with than single strand enameled wire! Here is the final build with the new motors and wires shortened to tidy up & save weight.

(http://s8.postimg.org/whc20917l/v2_Build.jpg) (http://postimg.org/image/whc20917l/)

To add piece of mind to this quad in case it goes down in long grass (or not so long given it's size!) I've fitted a loc8tor beacon to it. These are usually 5g with case and battery but by stripping off the case and running it from the 3.3v power provided though the FC's satellite socket (which I don't use as I use the built in rx) I got the additional weight down to just 1.5g. Initially I had this between the plates but the range of the beacon was poor, compromised by the carbon plates I guess so I moved it onto the top plate.

(http://s29.postimg.org/l04m2q4sj/loc8tor_top.jpg) (http://postimg.org/image/l04m2q4sj/)(http://s11.postimg.org/6ul4738u7/loc8tor_bottom.jpg) (http://postimg.org/image/6ul4738u7/)

Finally, I didn't like the placement of the rx antenna sticking out the side of the quad or the antenna material as it was non-springy copper wire that kept getting bent out of shape. To address this I used some tiny coax to extend the antenna upwards and out through a small hole in the top of the frame which has the added benefit of aligning it with my vertical tx antenna for maximum range.

(http://s13.postimg.org/7y0f1fzxv/antenna_mod.jpg) (http://postimg.org/image/7y0f1fzxv/)

As you can see, in this new configuration I got the weight down to 81g with the 450mah battery and just 72g with a 370mah battery (this is a couple of grams up now due to the loc8tor and longer antenna). These give around 9 and 6 mins flight time respectively so I think I will stick with the lighter battery as the weight saving is worth it.

(http://s30.postimg.org/ojnfcf97h/v2_full_build.jpg) (http://postimg.org/image/ojnfcf97h/)

Here is a compilation video of 4 flights taken mainly mornings and evenings so the light isn't brilliant and with 2 different DVR's.  It is an absolute blast to fly and so light it just doesn't seem to take any damage when it crashes (I've not even managed to break a prop yet!). It flies great outside and the main thing I notice is how quiet it is compared to my 250, it is much less obtrusive for flying in parks etc. where other people may be around and also much safer given it is about 1/5 the weight of you average 250 size racing quad.

http://youtu.be/AWGvqapk2h0 (http://youtu.be/AWGvqapk2h0)

Potential/planned improvements.

I am not brilliantly happy with the camera, it's not bad I suppose for £20 but the lens is too wide angle for my liking and the colour and resolution isn't brilliant, I have ordered up a RMRC Pico Wide V2 camera (http://www.readymaderc.com/store/index.php?main_page=product_info&products_id=1275) to try and will post back some comparison videos when I get it. I am also considering adding a Minum OSD running MWOSD (https://code.google.com/p/multiwii-osd/) to help with monitoring flight time and battery status etc. (as a timer just doesn't work well when you keep crashing and having to retrieve the quad as I keep forgetting to start & stop it!). There is the MX Nano OSD (http://www.overskyrc.com/mx-nano-osd-v1-p-555.html) that Oversky do that weighs a mere 1.5g but there is also the Witespy Micro MinimOSD (http://www.readytoflyquads.com/micro-minimosd) of which I have a couple on the way anyway so I'll see how much they weigh before ordering anything else.

If anyone else is thinking of trying a brushless quad of this size/type then the Oversky Hermit (http://www.overskyrc.com/hermit-micro-fpv-brushless-quadcopter-145mm-98g-p-599.html) is definitely worth a look as you can even get it BNF and there are also some other frames coming on the market now too.

To summarize, here is my final set-up:
Title: Re: Brushless Carbon Micro-H Quad Build
Post by: Brod on February 28, 2015, 04:39:51 PM
excellent build :)
keep us informed with RMRC pico V2 cam findings please
Title: Re: Brushless Carbon Micro-H Quad Build
Post by: iwan_canobi on March 01, 2015, 01:05:40 PM
That looks like great fun, nice write up as well!
Title: Re: Brushless Carbon Micro-H Quad Build
Post by: Billy_boy_2010 on March 01, 2015, 01:59:20 PM
Looks a hoot

It's far from slow too!

I'm slightly tempted by something like this as I have just bought a mini tri and could do with practicing on something less fragile.

How much was it?

How does it compare to the off the shelf products avaliable? Pros and cons? Several batteries must be a big advantage I would have thought.
Title: Re: Brushless Carbon Micro-H Quad Build
Post by: Coyote on March 02, 2015, 06:33:51 PM
Brilliant build thread, loads of information and pictures. Looks really nice
Title: Re: Brushless Carbon Micro-H Quad Build
Post by: HerkyBird on March 02, 2015, 08:25:50 PM
I haven't actually added up all the components yet so here goes:

So that's a scary £220 for such a silly little thing, I knew I shouldn't have added it all up  :-[

As for off the shelf, there's not much to choose from in the brushless world although plenty in the brushed line like the Hubsan and nQX's of this world. The only off the shelf option I know of is the Hermit that Oversky now do themselves, this is now a more cost efficient way to get the components I used and I think the basic frame (http://www.overskyrc.com/hermit-micro-brushless-quadcopter-145mm-not-include-dv-and-vtx-p-606.html) is the best way to go at £133 and add your own FPV components rather than getting the full FPV version (http://www.overskyrc.com/hermit-micro-fpv-brushless-quadcopter-145mm-98g-p-599.html) at £186 as I've not heard great reports on the standard DVR. Either way it seems to come out quite a bit heavier then mine at 98g with battery and every gram counts at this scale!
Title: Re: Brushless Carbon Micro-H Quad Build
Post by: Billy_boy_2010 on March 02, 2015, 09:32:14 PM
That's quite pricy. What what a great build- you clearly have something pretty rare and unique.

This is a complete idiot question- but what's the advantage of a brushless motor vs brushed on a tiny little quad like this?
Title: Re: Brushless Carbon Micro-H Quad Build
Post by: HerkyBird on March 02, 2015, 11:48:34 PM
I guess the main things are reliability and efficiently like any brushed vs brushless set-up. For me, I wanted something I could use outside that was bigger than a nQX but smaller and lighter than a 250 size quad so I could more comfortably fly it in a park. The challenge of doing something that I hadn't seen anyone else do before was also part of it I guess. I'm trying a 180 size now based on the microTHuG (http://tentech-rc.co.uk/thug-frames/new-microthug180.html) but using a few lighter components (but not true micro stuff like I needed on this one). I'll do a build thread for that too when I'm finished for comparison. I'm aiming for the 250g range for that build so notably heavier than the Carbon-H but still half the weight of my ZMR250.
Title: Re: Brushless Carbon Micro-H Quad Build
Post by: Billy_boy_2010 on March 03, 2015, 12:51:27 PM
Sounds great- must be exciting to have something so unique and to push the technology forwards- will look forward to the build log.

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