rctimer SM550V2 w/ Arduflyer 3dr and GPS first DIY attempt

[HowDoIfly]

After a brief intro to multirotors with an Ifly(away)4 I decided on the following kit as a replacement. The Ifly4(S) was originally recommended by my local hobbyshop as an entry-level quad for aerial photography. Lessons learnt from that, and much forum reading, this was ordered and is now in my possession.

http://www.rctimer.com/product_650.html  (F550 clone)
http://www.rctimer.com/product_837.html (Arduflyer2.5 with 3dr and NEO 6M GPS)

Tbh, I much prefer the look a quad over other MR configurations but as a man who prefers function over form, I felt the Hex would make a good starter package for me. Time will tell.

Considering I lost the Ifly, I was also warned the APM could prove complex for a novice flyer like me but as I';m learning more and more about the options, I still feel I';ve made the right choice. (Which admittedly, was largely governed by the wallet).

So, with a bit of luck and no doubt many, many requests of help from forum members, I hope this will be a mostly enjoyable experience. Let the games begin.

First off, I still need to source more parts and the burning question at the moment is what battery(s) will work best. I still have the spare Turnigy 3s 2.2A from the Ifly quad but this new build has two more mouths to feed. Recommendations welcome please.

[guest325]

I would look to making it 4S and around 3000-5000mah depending on what you are looking to do with it, be sure to get motors that are rated for 4S and don';t skimp on motor quality or quality of your props (the rctimer carbons are ok)

[shortwave]

4s 5000 mah 8" prop
Should do you well

[HowDoIfly]

What I intend to do with it: Aim is for a nice stable platform with stamina to do aerial photography so more of a cargo carrier than a fighter jet.

The motors and props are with the kit, so want to work with those for now.

A2212-930kv
KV(rpm/v): 930
Max Power: 130W
Battery: 2-3Li-Po
Prop: 12x6/10x7
Ri(M Ω): 0.044
ESC: 30A

I guess I';m stuck with 3s then?


The props... that';s still a mystery to me. Their kit states;
8045 Carbon Reinforced
though the motors spec says 12x6/10x7 and yet the ones they sent measure 10" and are marked 10x4.5   

[guest325]

If it were me I would try them out with a watt meter before I did any serious flying, too much amps and esc';s go pop!

[HowDoIfly]

That';s ubec and wattemeter both on slow boats from china then.

Been having a lotta fun with this build so far though most of the time has been spent reading, learning, testing, re-learning, testing again, reading more etc. It';s still in a mockup state having yet to decide best placement of parts but I have run the motors at high power with props on to test for magnetic interference and wasn';t expecting the cyclonic effect it would have in my living room.... some paperwork got lifted and shredded

I';m still after some parts though, particularly landing gear that gives clearance for a camera. Also need side-entry case and some means of mounting the gps module high.

[HowDoIfly]

Following the compassmot which, with APM sitting on ~15mm of foam on top board, it reported a 48% effect so last night I raised the FC by ~2inches and now it';s reporting 28%

I';m now at the point I need to do live flight tests though I';m still waiting for the ubec, meaning I';ll have to use one of the ESC';s to power the APM temporarily. Due to my first experience of MR';s ended in a flyaway and reading the problems others have had with APM flights, I must say I';m very apprehensive. Video to follow.

[HowDoIfly]

Well here it is, maiden test flight. Stabilise mode. All PIDS default. Got a bit of a wobble moreso in pitch than in roll. It was a nerve-racking experience, was physically shaking but glad it seems to want to fly ok-ish.

http://youtu.be/jRX0w-5_Wrs

[guest325]

Considering you were mainly flying in propwash that was pretty good, a bitmore space to play in will help no end!

[nub]

aye for sure looked not to bad to at all to me, n1

[HowDoIfly]

Thanks lads - there';s a few reasons I intentionally kept it low, main one being paranoia.

There was a point (not recorded) where I over-corrected descent and it went too high for my liking. On reduction of throttle, the wobble got more aggressive than I was comfortable with and had to power out of it so I';m even more paranoid about height now.

So my first task is to tune out the wobble but I can';t find any decent reading material on this that doesn';t involve using a channel6 pot (which I don';t have) or a holding rig (I';m certainly not going to try and hold it in my hand!). To make it worse, there';s conflicting advice - Arducopters guide says to start in STABilise mode but it also recommends DaveC';s guide who insists I use ACRO mode. 

[HowDoIfly]

I';ve come to the conclusion my stability problem is most likely due to two imperfect motors compounded by the resulting vibrations as chasing PID tuning almost ended in disaster when I took a leaf out of Peter Kings book and upped the Stab Rate from 4.5 to 5, which he finds works best for his hex';s.

The wobble on descent was worse on that setting, scared the beejesus outta me.  and almost discouraged me from testing Alt Hold for the first time. In fact, although I did engage it and it seemed to work well, my nerve went and I switched back to Stab mode, landed and came indoors for radio testing.

That hasn';t gone too well either. Noise is swamping the ground station as mentioned in my other thread.

[HowDoIfly]

Postie called today, replacement bearings, APM case, battery buzzer and soft foam. Motor is no longer wobbly or noisey and with the FC cased and sitting on soft foam, vibes are greatly reduced, leading to improved flight stability. Which is doing my confidence a power of good following yesterdays near brown trouser experience.

And to top it all, I';ve found a work around for the ground station USB noise problem. Having read others improving their signal by replacing the antenna, out of desperation and because it had the same sma connector, I tried a GSM antenna - the type you stick on your windscreen. Don';t ask me how or why it lowered the noise, but it did mean I was able to get the majority of the flight telemetry from 20 meters away onto my laptop this time.

And finally, feeling cocky, I ventured out to a local field at dusk, strapped a flashing led dog collar on the hex and wheeeeeeeeeeeeeee!  ::)

[HowDoIfly]

Bit of a roller coaster ride this learning curve. 

Stab P lowered to 3 seems to be much better than 5 or default 4.5 - how low can I go? Vertical descent can still be hairy though and I';m still thinking it';s to do with balance/vibrations which can be improved on the final build.

Encouraged by the drama-free Alt Hold test, I progressed to trying Loiter for the first time. It began well, sitting there all motionless. In fact I got my nose put out of joint as it was hovering better than I could  so I disrupted it with stick inputs - a touch of yaw and jerk of pitch etc and soon had it drifting off so abandoned that test. I did have a mind to quickly grab a shot of it.

http://youtu.be/ck_fEkWDh8s

As a result, I abandoned the testing of RTL and tried Land mode instead, which also worked better than expected. I need to be brave to test circle mode. Oh, and more batteries.

[guest325]

Looking very good, no more Ifly(aways) then!
   
Now that you';ve got something decent you can get on with enjoying the experience!!!

[HowDoIfly]

Looking very good, no more Ifly(aways) then!
   
Now that you';ve got something decent you can get on with enjoying the experience!!!

Well, until I';m confident RTL etc work, I don';t know about no more flyaways. Even with different coloured arms, there';s a certain distance (with my eyesight) they become indistinguishable and where I can';t tell if it';s pitching towards or away from me, regardless of the pretty LEDS. Think I';m going to need stronger lighting or something.

But my flying ability has certainly progressed well and you';re right, I am enjoying it much more now. 

[guest325]

One of the things it';s worth trying is having an upward facing led(preferably high intensity) pointing at your props, use the convention colours red and green on the front and white on the rears and it will make orientation easier.

[HowDoIfly]

One step forward, two steps back, they say? This is slow going for sure but I feel I';m making progress.

Finally got to test the other flight modes (except acro, simple and super simple) and I';m very impressed. They all seem to work without drama which should reduce my ';flyaway anxiety'; greatly. 

There';s still an underlying twitchy/instability issue I';m floundering to find the cause of - not for lack of trying but more a case of not knowing what to try next. I am somewhat hesitant to blindly experiment until I can get the vibration levels lowered further. Time to learn how to balance motors next, methinks.

[HowDoIfly]

I desperately wanted to capture the wobblieness I';m inferring so, apologies this is more miss than hit with the hex flying out of shot so much, but I hope it conveys my problem where someone can identify the probable causes? Thanks.

This is flown in Stabilise mode.

http://youtu.be/eFWEVBWIh_c

[HowDoIfly]

He';s crashed, he';s crashed, he';s crashed!

I was in the field enjoying a flight when rain stopped play briefly. The shower passed within a few minutes and as I setup for a second flight, I don';t know why but I failed to check the GPS lock indicator, armed and gently raised the throttle. She went up as expected but then got a left twitch on and began dipping and banking both to the left and rear. Either she wouldn';t respond to my corrections or I just made the problem worse but she pitched hard into the ground rearwards at ~45 angle. Result is two broken arms and the wires ripped out of one motor.

Now, I know that of all the failsafes APM offers, only the GPS one is enabled by default but I never discovered what action the APM should take when GPS lock is lost. Even more confusing is that in my case, GPS never was locked in the first place and the log only shows the failsafe was triggered. There are no MODE entries.

So I';m left scratching my head thinking, what the hell just happened????

[HowDoIfly]

p.s. The crash video
HexaCrash

I';m uploading another video from the previous flight as a comparison, which was flown minutes before this crash.

[HowDoIfly]

There you go - a comparison flight filmed minutes before the crash flight, showing easy to control Stab mode followed by Land mode.

Hexacopter fun

[HowDoIfly]

I have a theory - the FC came loose. That';s all. 

[HowDoIfly]

Now, I know that of all the failsafes APM offers, only the GPS one is enabled by default but I never discovered what action the APM should take when GPS lock is lost. Even more confusing is that in my case, GPS never was locked in the first place and the log only shows the failsafe was triggered. There are no MODE entries.

So I';m left scratching my head thinking, what the hell just happened????

For anyone that may be interested in the future (cos no-ones chimed in so far  ) I';ve worked out the APM would not have taken any action following the GPS failsafe trigger so I can eliminate that as a cause.

As per my previous post, it is possible the FC came loose and the prop draft lifted it causing the instability and resulting crash to earth. Unfortunately, I';m not experienced enough to see if this can be confirmed from the logs so it';s staying a theory for now, I guess.

In the meantime, I';m going to try a HK X650F quad frame, to see if the vibration problem follows as I';ll be using the same motors, props, esc';s etc. This is a stacked frame so I can get more distance between APM and magfields produced by power circuits.

I';ve also ordered a replacement motor (on a slow boat from China) so will be going back to the hex trials some time in the future.

[HowDoIfly]

If it were me I would try them out with a watt meter before I did any serious flying, too much amps and esc';s go pop!

Now the wattmeter';s arrived I can continue this thread but I forgot what I wanted to test it for now 

I';ve got make up the right connector leads for it but it seems light enough to attach for a flight so can get some readings.

One of the things it';s worth trying is having an upward facing led(preferably high intensity) pointing at your props, use the convention colours red and green on the front and white on the rears and it will make orientation easier.

As I already have some 5050 RGB led strips, I decided to put them on the arms (red on port side and green starboard) and tested them yesterday both during daylight and at dusk. tbh, they were nigh-on invisible in sunlight beyond a few meters.

[rickp]

Good move on the LEDs - red/green on the correct sides

In your tuning efforts, have you just changed STAB_P? Personally, I never touch those - get the RATE ones working first. Looks like you could reduce RATE_P for pitch and roll a bit.

[guest325]

As I already have some 5050 RGB led strips, I decided to put them on the arms (red on port side and green starboard) and tested them yesterday both during daylight and at dusk. tbh, they were nigh-on invisible in sunlight beyond a few meters.

They are not strong enough, I would use 1watt or even 3watt if you want to see them in daylight, and don';t forget pointing them up at the props works so much better!

[HowDoIfly]

In your tuning efforts, have you just changed STAB_P? Personally, I never touch those - get the RATE ones working first. Looks like you could reduce RATE_P for pitch and roll a bit.

Yes, STAB_P was the only tuning I';ve done so far mainly because I fly mostly in Stab mode and from DaveC';s guide, I get the impression RATE PIDs are for stick inputs which seem to respond very well for me. Additionally, until I can get the vibes within spec, I don';t want to get too deep into tuning the PIDs.

With the hex, turning STAB_P down to 3.1 really smoothed it out and likewise with this quad (same motors and ESC';s), I';ve gone to 4 and it';s improved so have lowered it more to 3.5 but haven';t tested it yet.

When I';m happy with STAB_P I will try RATE_P.

They are not strong enough, I would use 1watt or even 3watt if you want to see them in daylight, and don';t forget pointing them up at the props works so much better!

I was thinking of adding a white "headlight" (or perhaps strobe) LED to the front but read aviation/nautical rules requires white to the rear so   

As for reflecting off the props - does it work ok with black props? I';ve got some lighter props on order.

[guest325]

As long as the props are reasonably shiny it should be ok, I would avoid using white it';s too easy to get dazzled if it points your way - been there done that one got the badge!
If you are still having problems seeing them then you could give your props a light blow over with white spray paint, it works really well.

[HowDoIfly]

Ok, change of subject but very relevant to this thread - rctimer and first time experience.

I don';t know what to think, I feel sort of sad for rctimer. They offer excellent value but some products seriously let them down. To recap, I bought from them;

1. F550 clone, 2212 980Kv motors and rctimer 40A ESC';s
2. APM with GPS and telemetry

The main problems I found were two motors needed new bearings and the telemetry range was dire. rctimer';s responses were unsatisfactory so I sourced new bearings and fixed the telemetry with DIY antenna.

Too little too late, rctimer offered motor replacements after I felt compelled to file a paypal claim. I only wanted them to compensate me so set the claim high, knowing rctimer would "negotiate".

Now, I';m not sure how negotiations in china work but rctimers response " we can send two sets of bearings and new antenna".  :huh

I countered asking for a goodwill partial refund or, at worst, a credit off a future order.

They ignored this and the paypal deadline arrived - I escalated the dispute and paypal found in my favour and I got a refund of $60. No negotiation/argument at all