A newbies build log of a BumbleBee quad

[Flyinegypt]

Right, I have been lurking round the forums for about 3 months or so now so I think it is about time I contributed something practical.
Living in Egypt makes model building and sourcing components somewhat challenging. I have to plan seriously in advance so that everything I need for the coming year is ordered and ready for collection on a brief visit to the family in the UK.
I have been getting rather involved doing aerial photography for the Antiquities department and the foreign archaeology missions here in Luxor. It quickly became apparent that a fixed wing camera plane was not always the ideal tool for the job. Having to operate in limited spaces with rough ground presented me with some challenges this past season.

The obvious solution, I hope!, is to build a quad copter with a dedicated camera gimbal and GPS assisted control. Now bearing in mind I have very limited helicopter flying experience I am going to have a steep learning curve in more ways than one.

So, I did my research and now have a large collection of components from my recent visit to the UK.
My collection consists of:

Bumblebee quad kit with camera tilt gimbal from Hobby Lord
Set of 20A SimonK RCTimer controllers (with spares)
Set of HP2217 930kv motors (with spares)
Ardupilot Mega APM 2.5+ with Ublox LEA 6 GPS module
HK Quanum 2.4Ghz telemetry system with current/temp sensor
4 off Turnigy Nano Tech 3S 4500 35-70C packs
A collection of CW and CCW props in the 10-11" range
A big collection of connectors, silicone cable, heatshrink and various bit and pieces of screws, nuts, and spacers in steel and nylon.

The plan is to get all these components to fly in formation and in a controlled manner and do some decent photography!

I have a few months to do the build and get to grips with the Ardupilot control system and learn to fly a quad with the ease that I currently have with a fixed wing aircraft.
I brought back a Twister Quad with 5 spare batteries so I am hoping most of my learning will be on that before I put the big one into the air. The Twister seems reasonably easy to master indoors but I want to get it outside in a decent open space to expand the envelope. Trouble is it is around 38C outdoors even at dusk and we often get winds coming down off the mountain then even if it has been calm all day. I might have to force myself to get up at 6am and do some flying before it gets too hot.

Anyway, enough of the waffle, tomorrow I will start posting pictures of my progress...and no doubt asking loads of questions from the experts out there.

Barry

[Gaza07]

Excellent post Barry look forward to watching your build 

[Flyinegypt]

Ok, the first thing was to unpack all the components which had been carefully repacked for the flight back from the UK. Everything had survived the best efforts of the baggage handlers to wreak destruction. No chance, I have been doing this for a while now

Instructions on a CD were diagrammatic with chinglish text!
The diagrams were good however so I did not expect any major issues.

I did a dry assembly of the frame to check that all components were present. I found a couple of slightly misaligned drill holes in the fittings which required brief reworking and then I had a correctly aligned airframe.

The original full kit design had the esc's mounted at the end of the arms next to the motors. The RCTimer SimonK esc's were too big to fit in the housings and from my knowledge of wiring brushless motor setups I knew that it was not a good thing to extend the battery side wiring but it was ok to extend between the motor and esc.  I extended the output leads on the esc's and ran the wiring down the inside of the arms.

Next the motor wires were shortened to allow connection within the arm housings. These were then fitted and secured using my 20 year old bottle of Loctite 601 retaining compound on the screws. That stuff goes on forever!

[Flyinegypt]

I spent a few hours making up a power distribution spider. I got this design from a very useful YouTube tutorial. I incorporated the current sensor module for the Quanum telemetry system and the power module for the Ardu Mega 2.5. The extra pair of wires on the output side are for later use for lighting or video downlink.

I moved on to examining the Ardu Mega unit. I found that the casing had excess moulding flash by the power input socket and also the GPS socket. This prevented fitting the connectors so I removed the excess with a scalpel to get unimpeded fit of the connectors.

[Flyinegypt]

Today I started by watching the tutorial on th HK website for setting up the Quanum telemetry system. I then set up my equipment the same way and it worked as advertised...result!

Encouraged by this I then moved on to initial programming of the Mega APM 2.5 module...again following a YouTube tutorial. These online tutorials are really useful for someone who has no prior knowledge of this equipment and no mates to look over your shoulder and offer advice..

Initial programming with Arducopter V2.9.1b took only a few minutes and when I switched to the Flight Data screen the GPS had a good lock and I was looking down on my house. Considering this is the ground floor of a 3 story concrete and brick building I was very impressed. My Garmin handheld GPS has to be taken outside to achieve a satellite lock!

After lunch I installed the wiring harness having worked out the best routes for the various cables and systems. Next the Ardu Mega module was fitted on two layers of double sided foam tape on the top centre of the frame. An FrSky V8R7 receiver and the Ublox LEA 6 GPS module were also fitted with double sided foam tape.

Some questions for the knowledgeable ones...

Will 2 layers of 2mm foam tape be enough to provide isolation from vibration for the Ardu module or do I need something more "squidgy"?

Is my wiring layout and Rx antenna location ok or should I move items around for better noise/interference prevention?

[Flyinegypt]

Spent time with the Arducopter Wiki walk through's for connecting esc's and receiver to the Ardu Mega 2.5 and then worked through the Mission Planner basic setting up of Tx calibration etc. Some of the config screens seem rather complex and I am not yet sure what a lot of stuff means.

I mounted the camera gimbal and decided to wire the tilt servo direct to the Rx as this simplified the power arrangements and it also eliminates the possibility of "brownouts" on the APM according to the Wiki. I will probably wire the camera shutter trigger via the APM as this gives greater flexibility of shutter control.
I discovered that the length of the 4500 packs is such that, with the normal fore/aft battery shelf arrangement, the battery would be very close to the gimbal. To be sure I had adequate clearance I rotated the shelf by 90deg so the battery now sits across the frame.

I had to rewire the new packs with Deans Connectors to match my harness. These 3S 4500 35-70C packs are scary for someone whose previous biggest packs are 3S 1800 20C. The possibility of around 300A from a pack gives pause for thought, 

The wire dangling below the gimbal is the temperature sensor for the Quanum telemetry. This will get fixed to the battery platform under the battery pack. However, I don't think I will be over stressing the pack with only around 50-60A max drain.

Tomorrow I will be connecting up a battery pack for the first time to do the esc calibration and prop rotation setup so I just hope that I don't let the "magic smoke" out from anything.

[Flyinegypt]

I'm looking for some feedback guys.

Is my APM sufficiently flexibly mounted using the 2 layers of 2mm foam tape?

I also have some Moon Gel if that would be better. I got that for the camera mount but can get more in July if necessary.

[Gaza07]

I find moongel to floppy foam is much better, excellent build thread was avoiding posting until the end  

[Flyinegypt]

Ok, thanks. I will remount the APM with a couple of Moongel pads underneath.

[Gaza07]

I was saying i found moongel to floppy and it caused oscillations with the copter and I';m sure some one else on the forum found the same, but it may work for you 

Ok, thanks. I will remount the APM with a couple of Moongel pads underneath.

[Flyinegypt]

Ah! I misread that then I';ll leave it as it is for the first flights to see how it performs.

[Flyinegypt]

This morning I managed to hook up a battery and run through the esc calibration successfully.
Next a quick test of the motors revealed 2 were running in reverse. Motor wires swapped on those 2 solved that problem.
I then fitted the 10x4.5 CW and CCW props on the appropriate motors. These are the cheaper plastic ones. I have 2 sets of carbon fibre ones from RCTimer but these are for later when I have got my head around things better.
I could not resist a quick run up of the motors so clamped the frame to the floor and, after arming, ran the motors up. Not too much vibration so I took them up to full power for just a couple of seconds....wow! The max current on the telemetry showed about 40A on the partially charged LiPo pack so I guess my estimate of around 50A with a fully charged pack is about right.
The battery was then removed and placed on charge. My B6AC 80W was getting very hot charging at 4.5A in our 28 degC indoor ambient so I had to put a fan on it !
Next I removed the props one by one, balanced them and then refitted them.

For this setting up I have been following Jumpy07's guide and the links from it here:

http://www.multi-rotor.co.uk/index.php?topic=676.0

If it all goes wrong I can blame him....just kidding

I might try some basic ground running tests later today depending on the whether the strong wind drops down and temperature eases. We are going into the sand storm season so the wind is somewhat unpredictable at the moment.

A quick update: The wind just did not relent with dust blowing in the air so no testing was possible

[Flyinegypt]

Nothing doing today as the wind was too strong. I spent some time with my trusty JR 378 (FrSky converted) trying to coax a 3 position flight mode via the flap switch so I could achieve at least 3 different flight modes.
Stabilise, Loiter and RTH would have been nice but it is resisting my efforts. It looks as if I need to use the Glider configuration to enable that pesky 3 position flap switch. All the information says you must use "normal" aero modes on the Tx. I'll play safe and just keep all options at Stabilise for the time being.
We have an empty flat upstairs so maybe I will practise with my Twister Quad in there tomorrow. Much more space without furniture etc. It has a 3 meter high ceiling as well so some room for manoeuvre. Thinking about it I might be able to do the initial ground handling tests on the Bumblebee in there as well

[Flyinegypt]

I managed the ground handling tests after some tricky moments. The rather sticky rubber feet on the legs caused too much friction with the ceramic floor tiles and the quad tended to pivot over the feet rather than slide as I hoped. I put some slippery tape over the feet to reduce friction and was then able to rotate left and right and slither forward, back and left and right with the correct input commands.

Sandstorm building up outside so no outdoor efforts. Hopefully in a day or so It will be possible to get it into a decent hover. It just feels too confined even in an empty 8x4x3 meter room.

One thing I did notice after the tests was that 2 diagonal motors were hotter than their opposite numbers. Is this normal?

[Gav]

Where do you live?  I';m visiting Cairo in June for a week, on a business trip.  Give us a go on your quad and will save me packing one to fly over the sand lol.

[Flyinegypt]

@Gav

By June it will be in the mid 40';s C down here in Luxor (500km south)
By all means fly down and have a go with it!

[Flyinegypt]

Hey Guys!
I know it has been a while but the hot summer and life got in the way.

To continue, it has finally cooled off enough for me to start flying here again.
Or so I thought.
My first attempts to get my BumbleBee into an initial hover to start sorting everything out were a failure. The motors ran up smoothly enough but then, almost at the point of liftoff, I detected a clicking noise from the quad. As it became light enough to lift it tried to flip over backwards.

I decided to follow the suggestions in the initial flight test tutorial and arranged things so I could hold the quad in the air with safety and then throttle up. Sure enough there was a tendency to tip backwards towards one motor. This motor seemed to be running slower than the others. I clamped the airframe down and using my tacho went round the motors in turn. Sure enough the motor on the left rear of the quad was running considerably slower than the other three.

So, the question is how to proceed. I have a spare motor and controller so I can swap these out but before I do that I am wondering if there is anything else I should look at first.

To recap the Spec of the quad is as follows:

BumbleBee airframe
APM 2.5 with V3.01 loaded
Motors are RCTimer HP2217-93oKV
ESC's are SimonK 20A from RCTimer
Nano Tech 4500 3S
Props are HK 10x4.5 carbon reinforced props with CF versions in reserve.

[ericb]

Have you calibrated the ESC';s.....my crius on Sunday had this after an ESC change.

Eric

[Flyinegypt]

I did the ESC calibration when I was doing the initial installation back in May.
I guess it wouldn';t hurt to run it again to be sure.

[QuadBod]

Good to see another bumblebee user. I currently have an AIOP on mine running APM 3.01.RC, so if I can share anything by way of settings, just shout.

[QuadBod]

BTW, I have the four yellow feet at the back, and the black at the front - I find it helps with orientation when not using the lights. I';ve seen others with them down each side, but I prefer symmetry :)

[Flyinegypt]

I got to the bottom of the problem. It was the motor :huh
The motors I';m using are RCTimer HP2217 930Kv which I have been reading about here: http://www.multi-rotor.co.uk/index.php?topic=2899.0
I guess I did not make the best choice as far as quality control is concerned.
I replaced it with my one spare and it now lifts happily up into a steady hover at around 50% throttle. This was in the confines of our small garden. Today there were too many people/animals around the farm and on the field I was intending to use for longer flight testing. Hopefully tomorrow it will be quiet.

I think I will have to get a different set of motors (with spares) on my next trip to the UK.

QuadBod, I have all yellow feet at the front along with yellow front arms.

[QuadBod]

Okay, cool. I was commenting on your build pictures, but I guess you';ve changed it since.

[Flyinegypt]

The farm has been too busy for the last few weeks and other stuff got in the way.

So, today I finally gave up on the farm and headed out into the desert to a good spot. We laid out an old tarp and weighed it down with stones so I could fly from it without kicking up loads of dust and sand.
I successfully made about 10 short flights in "Stabilise" mode with traverses forward and back, left and right and a full yaw rotation. It seemed quite stable but a little sensitive in throttle setting to hold altitude. I also noticed that on a fairly quick descent it wobbled around and the motors sounded uneven.

Reading the various downloaded guides I noted that to cure this problem I needed to adjust the "Stabilize Angular Rate P" setting. No problem I thought but when I connected up with Mission Planner (build 1.2.84) the screen display for Tuning PIDS is completely different to the guides.

I found and read the post by Jumpy on tuning PIDS http://www.multi-rotor.co.uk/index.php?topic=1385.0
Unfortunately I could find no reference to the problem I was experiencing.

Can some kind soul please explain just what I should be tuning to eliminate the wobble on descent....preferably without too many big words

[HowDoIfly]

I would advise you install one of the RC candidates (4 or 5, I think) that includes the new AutoTune feature.
http://copter.ardupilot.com/wiki/autotune/

[Flyinegypt]

Bearing in mind I am a complete newbie to multirotors although I have flown fixed wing RC for about 35 years.
Is it wise for me to be using what is effectively a "beta" version of the firmware?
If it was deemed completely stable for general use surely it would be a mainline version.

[HowDoIfly]

I understand what you';re saying and tbh, I don';t normally update any software until it';s been widely tested by the general public but with this particular code release, many have already used it with success which led me to try it, also without drama.

Additionally, the developers of APM firmware will not release RC code lightly. They like to test it, at their own expense, rigourously and then add special logging in case of reported problems. From what I';ve read on other forums, there have been no issues that can be blamed on the code.

Obviously, it';s your call if you want to risk it and I wouldn';t blame for waiting for the more "stable" release. I';m sure it';ll come in good time.

EDIT: As Stab P relies on other PID';s, I wouldn';t advise tuning it first.

Another EDIT: This is an example of autotune';s final settings. Now I know, that if I set my hex to such a high Stab P ONLY that it would likely have fallen out of the sky being so unstable but combined with the other settings, it works well.
http://static.rcgroups.net/forums/attachments/4/1/3/1/4/9/a6207629-232-Untitled.jpg

[Cloudbuster]

Hi there flyegypt.... Quick quessie ??? I have visited luxor several times and am thinking of another visit in the new year !!! I am currently about to launch a new quadcopter for sale in the next month or so and am keen to do some promotional video work for the quad during my visit to luxor !!! Simply what are the legal implications and am i gonna get into loadsa trouble filming the monuments etc using my quadcopters, also am i likely to get problems from the egyptian customs bringing the quads into egypt. Hope you can help.

Regards rob 

[Flyinegypt]

@HowDoIfly.

Thanks for your comments and suggestions.
I will need to do some more reading on the RC versions with Autotune. I';m not sure I have sufficient usable channels on my X378 to operate Autotune safely. Hopefully will get a Taranis next Spring when I visit the UK.

[Flyinegypt]

@Cloudbuster

In a few words, don';t even think about bringing in a Quad and RC gear.
The Customs will work you over big time. My equipment was shipped in stages and assembled here. I am operating with oversight from the Antiquities authorities and do photography for visiting missions but any unauthorised operation over antiquities would get you in big trouble.

Give me a shout when you are coming over.