"Tricopter 2.5" tail motor issue, perhaps

[Lucian]

Hi all, I'm a noobie that was inspired by David's tricopter 2.5 blog all that time ago. It's taken me until now (or rather until 2am last night) to finally build it. Everything went extremely smoothly and I was very pleased with myself I've been setting up the TX and testing the motors (DT750) etc (still no props) and I've noticed that the tail motor does not start up with the front two. It starts at around 40-50% throttle I've calibrated all the ESCs (Turnigy Plush 18a) by connecting them to the RX, throttle up/down etc and programmed them with the Turnigy programming card as described by David. TX trims are centred.

The controller I am using is the HK Multirotor Control Board v2.1, flashed with the Kaptain Kuk Tricopter 1.6 as the KK2.1 was out of stock, all pots are set to 50%. I've had a go at calibrating the board using the zero pot setting, but to be honest I am a bit confused as the documentation for this board is a bit sparse, or maybe I need some sleep

I've tried swapping ESCs and motors, the same happens. When I hold the tri aloft and move it about at 50%+ throttle, the motors spin up and down the way they should, inc tail motor and the yaw mech works a treat. Anyone have any clues?

 

[CrashRecovery]

You need to calibrate the ESCs together. I have a feeling that is your problem

 

[Mustang7302]

Put the motors at 25% throttle and tilt the craft with the tail down. does that cause the motor to start spinning if it wasn't already to 25% throttle? Do the front motors spin up when you drop the tail?

 

[Lucian]

Thanks for the responses guys I haven't had a chance to fiddle with it again and it's beer-o'clock so off to the pub, will have a bash tomorrow!

CrashRecovery: Do you mean plug them all into the Rx at the same time for calibration?

 

[Lucian]

As an update, I've been fiddling for half an hour (not the best idea after a few pints ) and connected all 3 motors to the throttle channel with a piece of breadboard and jumper pins. All three come on at the same time, very smoothly (at around 5% stick!) so it all points at my board now I'll reflash it tomorrow at some point to rule that out, but I'm having a tough time figuring out where to get some decent documentation for this board. The HK manual is awful

 

[Lucian]

Anyone?

 

[Craftydan]

Lucian,

First off, I'm afraid most for us around here don't have enough experience with that board to know it's idiosyncrasies. I know it was a nice board a few years ago, but the newest boards are so far superior and have larger user bases to have seen *exactly* how it misbehaves. in this case you're trailblazing in ancient lands . . .

Secondly . . . what was the question? Post #5 looks like you're mid-debug -- confused, but more ideas to try.

I agree with your assessment, FWIW, something is up with that board, but seeing as it reliably sorta works in the same way, I'm inclined to think its software. Have you seen 1.6 is not the latest build? there's up to v2.9 in the kkMulticopter Flashtool -- granted I have no idea which are good or not . . .

It also appears someone had built a stick-driven menu that ran with an attachable LCD display -- completely bypassed/disabled the pots. looks like a cool version but you'd need to reconstruct the LCD it was designed to drive . . . and no idea where that's documented.

 

[Lucian]

Craftydan, thanks. I wasn't aware it isn't a popular board anymore, thought it was a HK version of the KK1 I guess the answer is to get a KK2.1 like I originally planned. Will have another crack at this board before that - not in a rush because the weather in ol' Blighty is typically damp and blustery anyway. I'm glad all my motors/ESCs behave correctly when controlled directly - they sound amazing btw

 

[Craftydan]

I know what you mean! That first hum as the beast comes to life is a real thrill -- This Crazy beast might just work after all!

Do try out the other roms, and feel free to report back (HK is still selling them, so if you can get it working you might become our "resident expert" when others hit this wall ). Unpopular doesn't mean it's useless junk, just means it's hard to help.

 

[Lucian]

Progress! I flashed to 2.9, problem persisted flashed back to KK1.6, problem persisted set all pots to nearly 0 and flashed to 2.9 again then put pots back to around 50% (on a hunch) success (almost!)

Now all the motors spin up when level, more or less. Front right (m2) is a little slow off the mark but only just. Might be a case of trimming it out, but I've not even put props on this yet and I have no idea what is normal. My only other multirotor experience is my battered Hubsan x4

 

[Tritium]

Those older boards work great but are VERY finicky to set up and I always found them difficult to get just how I would like them. They are very vibration sensitive so need to be mounted on foam tape pads (I used to use 6 layers in each of three spots under the board). As soon as the APM boards and the KK2.0 boards appeared my original boards were reflashed with Open Aero and now are used for Fixed wing craft stabilization.

Thurmond

 

[Lucian]

Mine is mounted on the foam lid of the box it came in, using pads of foam tape (doubled up all round), the whole package is then stuck to the frame with another 4 squares of doubled up foam tape

This tape is great, my Rx and low voltage alarm are also stuck on (and zip tied)

 

[Cyberdactyl]

I agree, I've wrote this before... but it's worth populating the forum so new people might read it...

The Atmega V2.1 & V3.0 is older tech with the gyros separate, and the aileron gyro, I believe, physically protruding off the board asking to be bent or broken. Low(er) sampling rate. Plus dealing with sensitive analog pots is a pain. For an extra few dollars above the V2.1 and/or the V3.0 ($10-15), the KK2 (now the KK2.1) is a no-brainer purchase, if you're interested in...

-better flying craft
-very good auto-level
-more reliable craft
-better control
-more fidelity
-MUCH easier to set up
-every setting accessible from the board itself (instant at-the-field changes, no PC interface)
-pretty much every multi-rotor configuration you could possibly want, already built in waiting for you to choose it
-have no need for gps

Even with the new KK2.1's disappointing changes from the KK2.0, it is still pretty much a must purchase for anyone coming into the full size MR hobby that is looking for a line-of-sight, no-gps, easy as heck control board.

 

[Lucian]

If only HK had them in the UK warehouse, I'd have one now. eBay sellers here want around £35-37 for them (~$60)

It will be my next purchase though