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Hello from Edinburgh, UK - Starting fresh

Hi there!

My name is Thomas, I'm currently living in Edinburgh, UK and I'm a big fan of RC models. I started with some electric cars and nitro ones (up to 1/5 scale) which was really fun. But then, I discovered the world of flying RC models: planes, helicopters, etc. and I really fell in love. It was 2 years ago.

My choice was toward the helicopter and I knew it would be difficult. I first bought some bi-rotors which were pretty easy to control. I then, bought the simulator Pheonix RC 3 (which came with the Specktrum DX5e) to learn I much as I could to going to the next step: a CP helicopter. I faced a lot of simulated crashes but I finally managed to take off, fly in a circle, 8 and land without crash so I thought it was the good time to do it in a real world. I bought an HonyBee King 2 and... That was the end of the fun. I spent more time crashing it than flying it. No, that not really accurate, I spent more time be frustrating than enjoying my toy. Was it too quick? Maybe I should buy a better helicopter, would be easier? I don't really know.

Anyway, I discovered one month flitetest.com and Wooow, all videos look amazing and the guys seems to really try to make to other's lives better with all the kits they create. I also discovered the tri/quad/hexa copter and as you can imagine, I wanted one! I told to myself that it was a shame what happened with the helicopter so I will redeem myself with that!

So I proud to announce that I should receive soon a Knuckle H-Quad frame, with all the electronic from HK. I seriously want this experience to be successful and I will try everything to achieve that. Hopefully it will be easier with the KK board and its auto-level feature.

Ok, I realize that is a really long speech for an introduction, I'll try to keep it short the next time. I see that there is a mentor section on this forum, maybe should I post over there to "find" one?

Anyway, thanks for reading me :)


Hostage Taker of Quads

Welcome to the forum!

Everything I've seen about the knuckle quad, it looks like a nice mini-quad - a real step up from the mall-kiosk toys, but a good small size (small side of medium, perhaps?) and easily controllable -- a good "sport" quad. between your experience with the coaxial and sims, you should have orientation licked which is what hurts most folks starting heli's.

The KK2 is a good choice as a control board for a scratch built. *expect* to reflash it -- the stock ROM is terrible at auto-level. It's not hard to do, but daunting the first time you try it.

Once it's tuned, the autolevel will help. A good coaxial heli is like balancing a marble inside a beach ball -- easy to do, but you gotta work to get it to do anything else. A CP heli is like balancing a marble on a beach ball -- everything is hard but the crashing. With a well tuned auto-level it goes from balancing a marble on a beach ball to flying on ice -- let go of the controls and it'll continue in the direction it was going like sliding on ice, and opposite input cancels out the motion. Fun and easy, but can take some getting used to. Once you're comfortable with it, then you can back off to acro and learn with just the gyros helping.

Keep us up on your progress, and don't hesitate to ask that silly question -- we've all had them.
Thanks for the reply and the warm welcoming!

As you said, the knuckle quad sounds pretty fun. I also took this frame for the video (as I already have a GoPro) because it keeps a clear view on a front, away from the propellers. But that will be in a future ;)

I'm a bit afraid by your comment on the KK2 board. Note that I'm not afraid of actually reflashing the board, I'm pretty confident with that, but that means that I have to order other stuff on HK to perform this operation :( (already made 3 orders to get everything)
I really though the stock firmware was fine out of the box. I think I have no other choice than learn it the hard way!

Oh and thanks for those described images regarding the way to fly different types of heli, it feels exactly that actually.

I'll keep you posted on my progress, maybe with some pictures of the build (if you are interested)
But first step is to receive all parts. In a meantime, I'll train on the simulator!


Hostage Taker of Quads
IIRC, it's still shipping with version 1.2. The acro on it is just fine out of the box -- good chance it'll do better with fine tuning -- but the self level is buggy and *very* sensitive to getting confused by any vibe. Problem is, there's always a little vibe. 1.6 is much less sensitive to the vibe confusion, and far more stable overall (slightly better response and fewer glitches).

No need to fear the "not-ready-out-of-the-box" with "but-the-programmer-is-never-in-stock". Pick up any USBASP programmer from a local-ish online source. They're used by electronics hobbyists to program their microcontrollers, so they're readily available and interchangable. Just make sure you get the 6 pin adaptor/cable, the 8 pin won't work without some type of adaptor. When buying from a good local source, It arrived far quicker than the US warehouse would ship, and wasn't that much more expensive. I ended up shelling out $10 for a nice one here in the states, so I wouldn't expect it would be hard to find an inexpensive one in the UK on ebay or amazon.

Once you get that and you're almost ready to start flashing, lookup flashtool lazyzero put together. It'll connect to a repository of reputable roms, most of which have links to their reference pages/threads. It's a good way to get a feel for what's available in the newer roms, and the threads will give you a feel for their reliability. IIRC, there are 4 branches of the kk2 rom and 2 other entirely independant roms in his repository for this board.

The acro mode alone will be a bit closer to the CP heli than the flat ice -- perhaps balancing a marble on a badly warped table than a sheet of ice. With only the gyros assisting, you're still balancing the copter while it's in flight, whihc ups the difficulty level considerably.

Whatever you do, get spare props, and balance everything as best as you can.
Ok thanks for those tips, helps a lot!

BTW, I bought 2 LiPos 3S 2200mAh, 20C for my quad. Do you think it's enough or should I get others like 25-35C ?


Hostage Taker of Quads
I think I've got 30C batteries, but a 20C battery can be safely emptied in 3 minutes, where the 30C can do it in 2. My flight times are ~9 min, but that depends on motors, props and weight of the platform, so YMMV.

Long story short, unless you're packing motors that can draw more than 11A (2.2Ah*20C/4 motors), you'll be just fine. Even then, it'll probably be ok, but you'll need to look a little more carefully at what it would actually draw with the selected prop. If all else fails, you'll be buying more packs soon, so you can fly more often -- I have four now and my "Add to Cart" finger is itching to pick up two more.

As for the programmer, it looks like it should work nicely. Yeah, you'll need to spring for the adaptor (or make your own), but the programmer is a pretty standard peice of kit.
Great! I'll do that then.
I just realize that the motors I ordered don't come with the bullet connectors... So I'll wait until everything arrive (all parcels have been shipped and should arrive later this week or the next one) to order the programmer for the KK2.0, the connectors AND a soldering iron.


Hostage Taker of Quads
Did you remember the male-male servo wire to connect the RX to the kk2?

I didn't.

I happend to have spare cable and plugs, so I could build a set, but WHAT A PAIN! I've you've got another order going in and you missed it, add on a set -- you'll need 5 cables, but IIRC they come in packs of 5.

BTW, which motors/ESCs/props did you pick up? (just curious, really)
Hi there!

I received the first parcel today :)
As expected, I will need to order other stuff on HK like gold connectors for the motors but for now, I'm happy with my delivery of the day!

2013-10-23 17.24.41.jpg


Hostage Taker of Quads
looks like you're most of the way there!

Have the knuckle parts arrived? (or are you planning on cutting those yourself?)

Once you've got the frame and parts together, you might want to check out The "Help keep Patrick from crashing his multi" Thread, that Flying Monkey put up a few months ago. It's got a good list of videos to step through setting up the board for first flight.
Thanks about the thread! I already went through a lot of videos / articles of how to setup the board but sure it will help. I even made my proper calculation of each motor's Pitch / Roll and Yaw regarding the exact measurement of the Knucke H Quad for a perfect setup ;)

I ordered the frame of the flitetest shop, it has been sent over the UK yesterday by USPS. I don't know this parcel company so I cannot say any ETA for now. I should probably take a look with the tracking number.

Anyway, I still have a lot of parts to received before actually build it.


Hostage Taker of Quads
Ok, now you've got me curious . . . most I've seen online are "how to guess and correct" procedures for PI tuning.

I've seen the math for hardcore PID programming in enigneering classes, but nothing applied to these control boards (and it's been far too long to remember the details).

What is this "Proper Calculation" for the "Perfect Setup" you speak of?!?!?
Yeah, I'm not talking about the PID programming, but the settings for each motor. As the Knucke H Quad is not really an X, you may want to adjust the layout (which you can do with the KK2 board) to match the exact measurement of the frame.

Long story short, if you look from the center of the quad, the motors angles are slightly different than a classic X pattern. For instance, M1 (front left) is -47° from Y axis and 43° from X axis which leads to the values:
Th: 100
Al: sin(43) * 100 = 68
El: sin(-47) * 100 = 73
Rd: 100
and so on...
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Hostage Taker of Quads
I see what you're saying. Interesting approach to setting the channel mixing.

This, however, is seperate from the PI loops (there's either no "D" or "differential" gain in the kk2's controler or the D is fixed at some sane level we can't adjust). Mixer settings tell the controller how to read the sticks to find the "right" ESC command. The PI settings adjusts how quickly you change from current-to-commanded based on gyro measurments -- too fast and you overshoot, too slow and you never quite get there.

Effectively, the control system measures an "error" -- gap between current and desired -- calculates a correction, applies the correction, and then repeats the loop. The P (proporional) sets how strong the current error influences the correction, the I (integral) sets how strong past errors inflence the correction.

D would have set error correction according to the diffrences between current and past errors (think: error slope), but if differential is set wrong it can make to control system unstable in all cases (arm the ESCs and the copter leaps in the air, then pirouettes into the ground).

Bit of a brain dump, and sadly most everything I remember from that painful class 15yrs ago. I suppose my point is, you've still got some PI tuning to do, but the quad should be close enough it'll be stable to tune using the test-then-adjust methods.

Not sure the angle offset calculations will yield "perfect" mixes, but a good chance it'll get you close. Most everything else will depend on the consistancy of the ESCs/motors/props, which you can adjust during tuning.


Hostage Taker of Quads
I am a native speaker, and mess up frequently ;)

And usually when scanning what's written -- yeah, you were clear, I was not.
Hi again!

Just a quick update to let you know that I received today all electronics from HK :D
I'm still waiting for the the frame and still have to order some cables & connectors for the motors but I'm almost ready to build it!