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New Electrohub quad pulls to the front left on throttle up.

#1
Newbie builder here with a very vexing problem...

I have an Electrohub in standard "X" layout.
Motors are Multistar 3525s
Controller is a Hobbyking KK 2.1 with the latest firmware 1.9S1 if memory serves.
30A ESCs from ReadyToFly.

So, my first attempt was pretty disasterous. I had a KK clone from Amazon, and it couldn't be flashed due to the wrong chip being in it (an Atmel clone that was reporting itself as a different chip version than the flashing software needed...) and some cheap ESCs.

When I tried to maiden, the quad careened towards the left front motor. Motor 1 on the layout. I went through all the options I could think of, and it still happened. OK. Well, as happens, motor 1 decided to release the magic smoke from itself and the ESC. Ahhhh...maybe that was the problem. Replaced the motor and all the ESCs. Still pulled. Tried to update the KK, which is when I discovered it was a really bad clone. So I got a new KK from HK.

And I am still pulling to motor 1! The quad will sort of fly, but I have to coax it up and even then it shoots off in the direction of motor 1.

I noticed that when the props are on, motor 1 looks like it is running slower than the others. It even stops slightly sooner than the others.

So....yeah. Very flummoxed here. This happened on both the old and the new setups.

The only thing that I have noticed is that the motor 2 boom is cracked down by where it attaches to the hub. It has a bit of wiggle. Not much....but some.

Could that be causing the problem? The KK board might be trying to compensate?

Help!
 
#2
UPDATE

I tried playing with the trim a bit in a more open area.

The results were some lost landing gear, and two broken booms.

I did record it though - So you can see what I am talking about.

So far, all I can find online about this are things regarding the subtrim, and a ton of people saying, "Give up and buy a DJI..."

*sigh*

Anyway, here is the video, and sorry about my hair...I need a haircut...

[video]https://youtu.be/QAmNUc4YyRc[/video]
 
#3
I watched your video, looks like to me you have a motor spinning the wrong way or a prop in the wrong place.

Double check the wires from ESC to proper place on the KK board. Ensure motors 1 thru 4 are correct. Remove props, put tape around motor housing, spin motors to ensure each motor is spinning in the correct direction. Then double check each prop to ensure that the CW and CCW props are in the right place, all according the the X layout on the KK board.

If all of this is correct, look at the acc and gyro bubbles on the KK board, ensure that is has a proper calibration. Bubbles should be centered. If not, get the KK board perfectly level and still,then do an ACC calibration. I had this issue once, the quad would fly away to the left like that, but did not flip over. The flipping usually indicates a motor or prop spinning in the wrong direction.
 
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#4
Thanks for the response.

I thought of this before. Just did a double check. Everything spins the right way round.

My props are on as follows.
1 - R
2 - L
3 - R
4 - L

Which, BTW, I THINK is right. Why the props don't have CCW and CW on them (or why we don't say R and L) is beyond me...Otherwise I start going, "Now if I stand this way, the props right is my left, but maybe that isn't the way..." and usually I suffer a microstroke from overheating my ummm...thinky head stuff.

Anywho, unless I screwed up on the props, I have no idea.
 

HarleyRev

Senior Member
#5
Generally props have something like 10×4.5 or 10×4.5R marked on them but don’t stress about it as the R just means reverse, the other one is normal


CW = Clock Wise = R

CCW = Counter Clockwise = not marked

images.jpg

images (1).jpg

Have you calibrated the ESC's ?
calibrated the KK board ?
 
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#6
Update -

Still not working.

The props and motors are going the right way.
The KK board seems to be fine. Calibrated it, etc.

No matter what I do, the quad wants to go to the left. I even swapped motors. Same problem.

I can get it into the air by "popping" it up with a throttle burst. But then I have a careening quad that wants to go forward and to the left. I can't even land the thing. It will ONLY...and I mean ONLY hit the ground at a 45 degree angle.

I am now looking at my 4th set of booms. Ever single attempt has resulted in busted booms. I even have massive foam landing gear on it and the booms still snap. Which is understandable since they are being driven into the ground at high speed. I mean, even on 50% and on a 3S 13C, this thing screams across the sky. Which is just not cool.

I played some with the trim and subtrim, but that is insanely hard to when you have only one shot at testing it.

My only guess at this point are the following -

1 - The Tx and Rx are screwed. I am using a Flysky 9x with the 8 channel receiver.
2 - Whatever force runs the universe hates me.

I have replaced motors...I have replaced the FC....I have replaced the ESCs. Nothing helps.

I am not at the point where I am really close to selling off this stuff, because at this rate, something more expensive WILL break besides the booms. I feel like I am just burning money for 0 reward. If I at least got it flying right, I would feel better.

Also, that front left motor (M1,) is 100% being messed with. By something. With the props on, you can see that on takeoff, it isn't spinning as fast as the others.

And like I said, I have swapped it out...done all sorts, and nothing changes.

It doesn't help that the local stores only carry poplar square dowels. Poplar has a relatively poor rating when it comes to bending strength...

Any ideas? This is getting beyond ridiculous.
 

makattack

Winter is coming
Moderator
Mentor
#7
I'm sorry to hear you've having so much difficulty with your quad. I'm afraid I'm not familiar with the KK2, but a quick search of KK2 firmware shows that you might be on an older version, if you are using the Steveis firmware:

http://www.rcgroups.com/forums/showthread.php?t=2144803

It looks to me like 1.17S1 is the latest. I believe that's one of the more popular firmwares for the KK2 board. I know there's another one, but can't remember the name of it. I believe this is the tool people use to flash the KK2:

http://lazyzero.de/en/modellbau/kkmulticopterflashtool#download

Anyhow, what mode are you flying in? Are you in ACRO/RATE mode? If you have self-level on, that might be a problem if the accelerometers aren't properly calibrated. I personally always test a new quad in rate mode just because it only uses the gyros. Once I have it tuned (PID's) then I will switch to the self level modes to test that mode and the accelerometers out.

Another way to test without breaking all the booms and props is to carefully hold the quad (with gloves and eye protection!) and while making sure to keep clear of all the props, run up the throttle until it's light, then using your hands, tilt the quad on pitch and roll axis to check that there's no oscillations and you can feel opposite force for a moment (if in rate mode). If it feels like it's always tilting towards a direction, don't fly it and try to debug it until it's balanced/level in your hands. Some people make test rigs using ropes/lines strung along the center of the quad (setup so you can pitch, but not roll) for testing.
 

HarleyRev

Senior Member
#9
poplar booms is what I use and have not had one break yet. Those crashes I saw in your video should not break a boom. What type of wood are you using ?

ok since you have replaced everything and get the same result, it does seem like something is giving you an errant motor input.

go to receiver test on the KK , ensure that the aileron, elevator, and rudder are at zero. Use the subtrims on your radio to get the zero. If all of these are at zero, i dont see how your getting any input from the radio that causes this error.
2015-05-03 22.14.47 (Large).jpg

If your radio has a "monitor" view, where you can see a slider that shows you the radio channels. Ensure that these are correct and move in a correct way.
2015-05-03 22.13.04 (Large).jpg

do you have self level on when lifting off ? if not try that, it should keep it level after take off, it may still try to fly away, but should stay level and not crash. Then perhaps you could get some stick time in and maybe find the problem.

i use stick scaling on the kk and 60% dual rate with 30% expo
2015-05-03 22.23.30 (Large).jpg

double check receiver channel map on the KK board, ensure those settings are correct for your setup.

look at mixer editor
2015-05-03 22.28.02 (Large).jpg
mine is set for "X" configuration too, your settings should look like this by default, with each 4 channels being similar, atleast with the 100 and 71 numbers, each channel has a mixture of positive and negative numbers.

Go to show motor layout, ensure it shows the pic of X configuration.

gyro bubbles look like this ?
2015-05-03 22.32.37 (Large).jpg

end point limits all max at 100 ?

try to find a balance point on your quad, use your fingers to balance it, ensure that it is not heavy on that side. I dont know what could make it that much heavier tho.

Report back here your kk board settings, if your using auto level on your flights, receiver test status, PI settings, maybe we can figure this out. I feel for ya man, I know you put alot of work into this and you want it to fly. Dont give up, Im having similar issues trying to learn how to fly a plane, when I feel like giving up I put the plane away for a few days, then next thing I know I start wanting to try to fly again.

You are very close to flying, so very close, you can get this figured out. Anyway you can post some pics here of your quad, top view, bottom view, few different angles, would like to see your wiring connections. I had an issue early on with a power connector board I used that was causing a motor to not work properly, as well as a motor connection problem, faulty soldering on factory bullets.
 
#11
VICTORY!

I went back over everything and discovered two important things -

1 - I wasn't getting into self-level mode at all. So, that explains a ton right there. Turn it on with sticks now. Going to wire it to Aux soon.

2 - I checked to see what the receiver was getting from the tx. Had some serious trim offsets that couldn't be changed. Hmmmm...played around a bit, and turns out my Flysky 9x was set in the wrong mode. Great for a standard heli, not so great for a quad. Played around and found the right mode...ended up with just having to add +11 on the trim for A and E, and all was good.

With self level on, it is much easier. I still need to wire in the aux for self-level and do my PID, etc. Far from perfect at this point, but it is up and responding. I even managed to drain my 4s 2200 while playing with it. I need to work on my CoG and play around with landing gear options. Get the transmitter tuned in with stick scaling, etc.

Thanks for the help so far. Learning a ton.

And I must say, the Electrohub design is rock solid. I have blown through booms and zip ties, but that is all. Thing is a champ. Great platform.

Here is my very rough maiden...

https://youtu.be/DicUUh1Y6M8
 
#12
poplar booms is what I use and have not had one break yet. Those crashes I saw in your video should not break a boom. What type of wood are you using ?
Not very good wood. I can say that for sure. Finding a straight(ish) 36" of this stuff is not that easy. I know one batch was Chinese, too. So, "Poplar" might be a term, how shall we say...lost in translation. It never seems well milled.

I do need to figure out my stick scaling and trim still. Feels front heavy and tends to drift to the right.

I have yet to try it with self-level off. I am not at that point yet. What I think I may need at this point is more throw on the low end of the controls. It tends to get a hair ahead of me right now when I am trying to do simple things like hover 10 feet up and do a 360 with the yaw. Certain to get better when I tighten things up and start getting it stable, but I'm feeling like caution is the way to go here. As I get better, I can change the settings. That is one reason I went with the KK2.1.5... Cheap and it's all there for you to fiddle with.
 

NHS77

Senior Member
#13
Not very good wood. I can say that for sure. Finding a straight(ish) 36" of this stuff is not that easy. I know one batch was Chinese, too. So, "Poplar" might be a term, how shall we say...lost in translation. It never seems well milled.
My wooden booms broke all the time as well. Switched to 10x10mm aluminium booms from the local hardware store. No more than 10 bucks. Weight is almost identical and they've held in some fairly ungraceful crashes. Definately worth the upgrade.
 
#14
AWESOME ! So glad to see you have flight now ! Last time I was at Lowes looking for poplar wood, they had the cheap chinese stuff, I wouldnt use this wood. What I saw from this wood is it is never straight, and it feels almost like balsa wood. The quality of the wood from china does not compare with true poplar. True poplar wood has that greenish tint or grain in it. This is good wood, strong and light.

Congrats !
 
#15
Thanks, HarleyRev, and let me say, I couldn't have done it without your advice and the advice of others. One big reason for me going with the EHub was the fact that I knew I could count on Flitetest.com for help when I needed it. The community here is such an added bonus to the product.

I am also going to start looking for better booms. Aluminum is probably where I will end up...although for the next batch of booms I think I will seek out a real lumberyard.

That BTW is another reason I love the EHub...I can play with designs as I want to and then "commit" to more expensive booms as I need to. For a newb like me, that is a great way to learn.

Although a nice fast 250 FPV rig is in my future...
 

Balu

Lurker
Staff member
Admin
Moderator
#16
Just make sure that you don't shorten any contacts if you are using conducting materials. Your electronics might not like that.
 
#17
Oh, yeah, I am well aware of that...
Since the amps on these things can get up there, I approach the wiring very cautiously and have been hitting the shrink wrap and "Liquid Electrical Tape," hard. This isn't some piddly 250mA AVR board.... Sparks can fly!