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Old Jan 02, 2013, 09:36 AM
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Originally Posted by jrjr View Post
Ok with that said.... in a perfect world my quad is straight and square, the motors at four corners are perfectly level, but I cannot get to my board to put a level on it. Lets say the board is off .5 degrees when I calibrate but the motors/props are all perfectly level.

What you are saying is that that .5 degrees will be attained when auto level is turned on, which, will also bring my props/motors back to perfect level as they were when calibration was done...... resulting in (in a perfect world with all outside forces disregarded) level hover.

Edit.... don't know what Naza is, I am new to multi copters
In the real world, it is not possible for the flight controller to level out both the flight controller itself and the frame because the flight controller itself could be sitting un level on a level frame due to bad mounting. Leveling out the flight controller in flight can still result in one motor sitting tilted or higher than another when compared to the position of the flight controller. This will result in in an un level hover with constant corrections.

The best you can hope for is to build the multirotor as level as possible before mounting the flight controller and then mounting the flight controller itself level. You can use a small bubble level to check the flight controller itself and a larger one to check the frame.

If you believe that all is as level as it can be and you still have drift in flight, you can shim the flight controller and/ frame together when performing the IMU calibration. This tricks the flight controller into using that position as its basis for level.
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Old Jan 02, 2013, 09:52 AM
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Originally Posted by rcjose View Post
In the real world, it is not possible for the flight controller to level out both the flight controller itself and the frame
Nope, thats why I believe putting a level across the motors is the best way to do the initial setup and then get the board as close as possible. After that then tune for how it flies. There are other ideas and that's ok but this is mine
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Old Jan 02, 2013, 09:53 AM
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Originally Posted by brontide View Post
Correct, the important thing is that the props should be "level"
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Originally Posted by jrjr View Post
I have a couple questions
It seems to me when doing acc calibration that one would want the props level and not really care about the board. After all, the props are what are going to keep the bird level. Am I wrong in my thinking? I spent a great deal of time shimming the frame with a 2' level across motor shafts each way and got it right on the money before calibrating. Seems to auto level well so far but my testing is limited.

...
There are some ships where leveling it perfectly simply doesn't work. Take a normal heli for example. It hovers with the main rotor disk slightly tilted to counteract the tail rotor constantly pushing it sideways (in addition to spinning it around). Unsymmetric quads with all motors using servo pivots is another case.

In addition, you have repairs from crash damage and home made ships that use motor mounts glued on round shafts. These won't be perfect either, and "level" in the air will be different than "level" on the flat ground.

I believe that is what the "ACC trim roll" and "ACC trim pitch" are for in the Self-Level Settings.

Rather than split hairs getting your ship perfectly level and it still being wrong at the field and you have to level it again and try again etc., you just tweak these trims.
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Old Jan 02, 2013, 10:01 AM
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Originally Posted by theothercliff View Post
There are some ships where leveling it perfectly simply doesn't work. Take a normal heli for example. It hovers with the main rotor disk slightly tilted to counteract the tail rotor constantly pushing it sideways (in addition to spinning it around). Unsymmetric quads with all motors using servo pivots is another case.

In addition, you have repairs from crash damage and home made ships that use motor mounts glued on round shafts. These won't be perfect either, and "level" in the air will be different than "level" on the flat ground.

I believe that is what the "ACC trim roll" and "ACC trim pitch" are for in the Self-Level Settings.

Rather than split hairs getting your ship perfectly level and it still being wrong at the field and you have to level it again and try again etc., you just tweak these trims.
So you just throw the thing all together and go fly it. Well that should work after tweaking which needs to be done either way, but I tend to be a bit more of a perfectionist. It only takes a minute to level it anyway and then I know where I started and can return to it if needed.
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Old Jan 02, 2013, 10:07 AM
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Originally Posted by jrjr View Post
Edit.... don't know what Naza is, I am new to multi copters
Naza is a very expensive KK2 like board, but with GPS which is used among other things to keep it from drifting.
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Old Jan 02, 2013, 10:10 AM
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Originally Posted by carr52 View Post
Got my first T-Copter done using a KK2 board. I didn't change any of the P or I settings. Mainly because I haven't got the slightest idea what to change. I did set the throttle limit to 20. Now all the motors start at the same time. My yaw setup is kinda simple but I believe it will work. I'll take some pics tomorrow and post them. I set the volt alarm to 110.

Tom
If you had to bump up your throttle min to 20 to get them to start at the same time, then it sounds like your ESC's need calibration.
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Old Jan 02, 2013, 10:11 AM
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I stopped hovering all that much, problem solved.
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Old Jan 02, 2013, 10:16 AM
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Originally Posted by theothercliff View Post
If you had to bump up your throttle min to 20 to get them to start at the same time, then it sounds like your ESC's need calibration.
I did the calibration when I set it up. Can I recalibrate and is it a bad thing to have the throttle min at 20?

Tom
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Old Jan 02, 2013, 10:20 AM
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I did the calibration when I set it up. Can I recalibrate and is it a bad thing to have the throttle min at 20?

Tom
Me too and still need min set to 20. Works fine though so far
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Old Jan 02, 2013, 10:21 AM
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I stopped hovering all that much, problem solved.
That would do it! lol
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Old Jan 02, 2013, 10:46 AM
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Just took the lil fella out for test fly. To say I am pleased would be an understatement. It needs a little trim work but it flys great. Didn't trim it out because I found out my battery alarm works great also. Quick recharge or new battery and we'llbe back at it. Also need to calibrate self level. This KK2 board even makes a computer dummy like me look good. Thank you.

Tom
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Old Jan 02, 2013, 10:55 AM
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Originally Posted by carr52 View Post
I did the calibration when I set it up. Can I recalibrate and is it a bad thing to have the throttle min at 20?

Tom
Not a bad thing. I have calibrated the ESC throttle setting so that is not the issue, but still find that it works better with the throttle trim bumped up to 20, or whatever works best. My experience is that it reduces the dead band as the throttle is advanced for takeoff and helps all motors to start spinning simultaneously, but 20 is not a magic number. Experiment to find the value that works best for you.
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Old Jan 02, 2013, 10:55 AM
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Originally Posted by carr52 View Post
Just took the lil fella out for test fly. To say I am pleased would be an understatement. It needs a little trim work but it flys great. Didn't trim it out because I found out my battery alarm works great also. Quick recharge or new battery and we'llbe back at it. Also need to calibrate self level. This KK2 board even makes a computer dummy like me look good. Thank you.

Tom
Great to hear! Mine flew good with the stock settings too. It's a big rush isn't it? Also thanks for the nudge to get one of mine airworthy again.

Cheers,
Andrew.
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Old Jan 02, 2013, 11:07 AM
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Originally Posted by flarssen View Post
No. First of all, 3A is just a max current for the regulator chip. How much current it can handle in real life, depends on the gap between input and output voltage and cooling. On 3S Lipo, 3A would mean that around 20W ( (12V-5V)*3A ) is turned into heat in the BEC.
When paralleling BECs, if they all have excact same voltage, you can multiply available current by the number of BECs. If they have slightly different voltage, the highest one will always deliver more current then the rest. Usually the resistance in wires and connectors in between, makes them share current pretty well, unless voltage differs greatly. I wouldn't expect more than 2-3A total current in your case.

Fred
Roughly speaking, the lion's share of the first amp or so will all come out of one ESC. For a typical system with a 3S lipo, that means that one ESC will get pretty hot before any other starts to share the load. If you increase the load to the point that the second ESC is getting hot, the first one has probably gotten hot enough to damage itself.

N.B. Pulling even 1 amp out of the typical linear BEC that is built into the typical 30A ESC with a more than a 2S battery will make it get damagingly hot very quickly. 2S setups generate much less waste heat and would probably be safe up to a whole amp average. For the common 3S battery configuration, considering that most of the current will be coming from one ESC, you can only safely pull maybe 1/2 amp average. 4S setups and especially higher setups generate so much waste heat that I won't state any rule of thumb for them except that using a switching BEC speced for your needs is best. Each system needs to be checked individually because of cooling differences, etc.

You could get easily 6 amps from the lot (3 ganged ESC's with linear BEC's on 3S) with heat being the big issue, and it is a permanent damage quickly kind of issue. Low duty cycle loads up to 6 amps would probably be OK if you always keep the 10 second average below 1/2 amp (3S). The problem is that we generally don't have low duty cycle loads. Servos get exercised continuously during stunts.
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Old Jan 02, 2013, 11:14 AM
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Originally Posted by Soul Reaver View Post
Probably stupid question and maybe a little ot but... What's the difference in setting the model on the tx (9x) as heli or acro?
I set my as heli, but I see that acro is suggested. Heli should have helicopter settings too, but is there any difference when using a quad?
Acro has the four functions doing exactly what you expect and nothing more. This is what the KK2 expects for inputs: exactly what the stick is saying.

Heli can also work that way, but often have things that confuse the issue and need to be turned off. You don't want CCPM. Pitch and throttle curves need to be flat. Idle up is not wanted. 3D throttle and pitch are not wanted. Throttle trim and pitch trim knobs can cause problems if they get bumped. Should you use the throttle channel or the collective pitch channel? Better to avoid all these questions and just tell the user to use airplane acro mode.
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