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Multi-Rotors Discuss your quad copters and other multi engined choppers here.

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Old 06-11-2014, 04:35 PM   #1
leadpan
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Default H-quad dilemma: weight

Hi folks,
Completed my mod build for 470mm H-quad from HobbyKing with 3/4" aluminium frame and arms. I was happy how it looked until I lifted it. It's heavy! I did order (4) powerful 900kv motors, but worried esc or motor won't handle it. I thought two remedies:
-Replace the two aluminum arms with wood.
-Cut and shorten the aluminum arms.

Ideas? Suggestions?


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Old 06-11-2014, 06:10 PM   #2
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Take a look at this link....there's plenty there to digest. UAVJOE's post's are very similar to your set-up and he's had lots of success without reverting to any wooden platform on the HK H4:

http://www.rcgroups.com/forums/showthread.php?t=1866453

Your biggest hurdle will be weight/power ratios once you add the batteries, which may end up being a combination of 2-3s 2200mAh.......since the design is a rectangle rather than square, balance issues after loaded-up with equipment come into play as well.

Motor mounts on the stock design seem to have problems with vibration and stability.......if you intend to vid anytime soon......

Looks good leadpan....progressing quite well!

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Old 06-11-2014, 09:39 PM   #3
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Many of these quads are very heavy on the ground, but seem to fly great.

You say you have powerful 900 kv motors, but we don't know the wattage.
Look up a quad calculator online and plug in your values, then you will have an idea.

Fly it first then modify, if necessary.

Dave R, Proud PGR rider.
When you have flying skills like mine,
You become a master at repair.
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Old 06-17-2014, 04:07 AM   #4
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Default PI tune help

Almost ready to maiden but I notice that when I was tuning it would lift FORWARD.
It's bit heavy at 2000grams and I put 12x6 props.

Here's my setting:
P gain = 30
P limit = 100
I gain = 0
I limit = 20
Yaw I gain = 0
Height dampening = 0

And is it normal for my H-quad to start lifting about 55% throttle?
Help!


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Old 06-17-2014, 06:19 AM   #5
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Without knowing what operating system or whether or not your'e GPS loaded and if the ESC's your'e using are programable....it's hard to say....it could be a dozen different things.

Here's a few checks anyway:

Considering at almost 4.5lbs (assume with batteries) and 12x6 props (hopefully calc'd at the proper ratios)....lift should not be due to weight.

Unless TX values have been set intentionally, quad should lift at least at 10% to 15% throttle.

1) TX throttle end points may need to be calibrated.
2) ESC's may need to programmed in harmony with TX and OP system.
3) Batteries (or single) may not be providing enough power to everything.
4) If GPS loaded......need to re-check calibration and celing values.
5) The forward lean is due to C/G balance, but is normal under extreme acceleration
6) Quad props are LH & RH oriented, check positions of each. 12x(6) could be an issue.

That's a 1/2 dozen checks........of common lift issues.

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Old 06-18-2014, 12:28 AM   #6
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Default failed maiden flight

My failed maiden flight.
If you can look my my vid and tell what's wrong with my quad?
I think I need to reduce weight by swapping out aluminum frame with wood or something. I have no GPS yet, props are in correct rotation. I think my motor just can't handle this weight.

https://www.youtube.com/watch?edit=vd&v=4hQTQxRm2Ls
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Old 06-18-2014, 03:27 AM   #7
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Hey Leadpan

The weight is not making it flip over. When loaded to the max they seem to struggle at lift off but all of mine still lift off upwards. If completely overloaded they seem to lift then settle.

Your video reminds me of first flight attempts that had something reversed. Motors, esc connections or servo channels are the most common reversals.

Are you using the KK 2.0 board.? Why no I gain? Are the roll and pitch linked?


To check the system out. Take the props off. Arm the quad. pick it up stay clear of the motors and bring the throttle up. Lean it forward and the front motors should speed up, lean it back and the rear motors should speed up. Repeat this with left and right roll then move it to lower one motor at a time. The motor that is the lowest should speed up. Lastly holding it level move the pitch stick forward, the rear motors should speed up. Pitch back = front motors speed up. Stick right = left motors faster and stick left = right motors faster. Please do not try this with the props on.

If all this checks out it should be able to take off. Have you calibrated the sensors.

Let us know what controller you are using and if these checks show that all is working correctly and we can go from there.

Be safe those carbon props are very stiff.

Terry

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Old 06-18-2014, 06:10 AM   #8
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I will check the motor connections and ESC. I'm using KK2.1 board.
But in few days APM2.5 board and GPS is coming. So i am thinking of starting over with that.
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Old 06-18-2014, 11:02 AM   #9
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If everything is correct and it will not fly with the KK board then it will not fly with the APM board. Plus the added complexity of the APM will take much longer to tune. It would be smart to make it flyable with the KK. Leave the autolevel off for the first hover.

Terry

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Old 06-18-2014, 03:05 PM   #10
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After removing the frame, arms, and motors; I think I know the problem. The quad was top-heavy from the arms and motors. I'm replacing with wood arms and check the difference.
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Old 06-24-2014, 11:57 PM   #11
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Having trouble getting the ESC calibrated.
What am i doing wrong here?
Also got this HK 15a UBEC; but not sure where wiring plugs into?
Do my lipo plugs into UBEC red wire and the 2 y-wires plugs into the APM2.5 output pins?

https://www.youtube.com/watch?v=o8iMX4R2VUY


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Old 06-25-2014, 12:16 PM   #12
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Try to calibrate them one by one connected directly to the throttle channel of the receiver. You can use a "y" connector and calibrate two at a time.

For the BEC I solder a connector to the power distribution board that connects to the BEC. You can also buy a Deans to Deans with a JST connector. It plugs in line with your battery and provides a connector for the BEC.

Most boards have a system for power input. The Crius board I am running Ardcopter on has a jumper that selects power from the ESC or the BEC. I have removed the jumper and connected the BEC to the receiver then to the secondary power connection.

When I try to power the board with the USB I must remove the BEC's connection to the receiver. I have not figured that one out yet.

Terry

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Old 06-27-2014, 06:45 AM   #13
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Finally got H-quad frame built with wooden arms and APM2.5.2!
I was able to Save Trim:
http://youtu.be/ooNPJr7hrno

But problem I discovered is interferances.
Using Mission Planner "compassmot" the result:

-at 10% throttle: 57% of mag field
-at 50% throttle : 151% of mag field
-at 80% throttle: 229% of mag field


Any ideas on how to reduce the interfaces or shield the APM2.5?
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