Hello Everyone :nevreness:
My goal is to build an octocopter that will be able to lift a 15lb to 25lb payload and fly for at least 15 minutes (hopefully more).
The problem I’m having is with reading the specs of the components.
Some are only in Chinese, some are inaccurate, and there doesn’t seem to be a strong standard to make an apple to apple comparison.
So I built what I thought would be a heavy lifter, only to find out that it isn’t quite up to the task.
Here are the components I’m using (won’t include Naza and other components non-essential to flight time and lift):
* Hobbyking X930 Glass Fiber Octocopter Frame 895mm (Heavily Modified)
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=26455
* (8) NTM Prop Drive Series 35-36A 910Kv / 350W
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14847
* (8) HobbyKing F-30A 30A SimonK Brushless ESC w/ 3A 5V UBEC
* (8) 11X4.5 Props
* Turnigy nano-tech 6000mah 3S 25~50C Lipo Pack
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=20681
** Weight of the craft: 8.5lb
** Weight with 1 Battery: 9.5lb
** Weight with 2 Batteries: 10.5lb
** Weight with 3 Batteries: 11.5lb
*** Flight time with 1 battery: 6.5 min
*** Flight time with 2 batteries: 12.5 min
*** Flight time with 3 batteries: 11.5 min
As you can see, the weight of the 3[SUP]rd[/SUP] battery (approx. 1lb) nullifies the benefit of the additional 6000mAh and actually reduces the flight time.
Now this one is a big problem for me because my camera and gimbal weigh 5 or 5.5lb:
*** Flight time with 2 batteries and a 5lb payload : 3.5 – 4.2 min.
-----
One thing that I noticed in hind sight is that my battery is only 25C rated, and my motors max out at 38 amps. HobbyKing sold me the motors and their listing suggested 30amp ESC.
My tests showed that the max amps that I could draw with a 12” prop was 23.6 amps and with an 11” prop the max was 20.1 amps.
Because of my tests I felt comfortable with the 30 amp ESCs, but I’m wondering if the battery’s 25C rating is responsible for the low max amp readings or that the HK specs are just off??
I have some questions:
-- Would a higher C rating battery actually give me better (higher amperage readings) test results?
-- Would a higher C rating give me more lifting capacity?
-- Would a higher C rating give me more flight time?
-----
**** Here is the million dollar question… What do I have to do to upgrade the above octocopter to lift 8lb and fly for at least 15 min?
-- I like these motors, they’re smooth and I feel I can trust them… Is there anything I can do to get more lifting capacity and flight time out of them?
-- What motors would give me the results I’m looking for?
-- Would more cells make a difference?
Any advice and feedback is greatly appreciated!!!
Anthony
My goal is to build an octocopter that will be able to lift a 15lb to 25lb payload and fly for at least 15 minutes (hopefully more).
The problem I’m having is with reading the specs of the components.
Some are only in Chinese, some are inaccurate, and there doesn’t seem to be a strong standard to make an apple to apple comparison.
So I built what I thought would be a heavy lifter, only to find out that it isn’t quite up to the task.
Here are the components I’m using (won’t include Naza and other components non-essential to flight time and lift):
* Hobbyking X930 Glass Fiber Octocopter Frame 895mm (Heavily Modified)
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=26455
* (8) NTM Prop Drive Series 35-36A 910Kv / 350W
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14847
* (8) HobbyKing F-30A 30A SimonK Brushless ESC w/ 3A 5V UBEC
* (8) 11X4.5 Props
* Turnigy nano-tech 6000mah 3S 25~50C Lipo Pack
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=20681
** Weight of the craft: 8.5lb
** Weight with 1 Battery: 9.5lb
** Weight with 2 Batteries: 10.5lb
** Weight with 3 Batteries: 11.5lb
*** Flight time with 1 battery: 6.5 min
*** Flight time with 2 batteries: 12.5 min
*** Flight time with 3 batteries: 11.5 min
As you can see, the weight of the 3[SUP]rd[/SUP] battery (approx. 1lb) nullifies the benefit of the additional 6000mAh and actually reduces the flight time.
Now this one is a big problem for me because my camera and gimbal weigh 5 or 5.5lb:
*** Flight time with 2 batteries and a 5lb payload : 3.5 – 4.2 min.
-----
One thing that I noticed in hind sight is that my battery is only 25C rated, and my motors max out at 38 amps. HobbyKing sold me the motors and their listing suggested 30amp ESC.
My tests showed that the max amps that I could draw with a 12” prop was 23.6 amps and with an 11” prop the max was 20.1 amps.
Because of my tests I felt comfortable with the 30 amp ESCs, but I’m wondering if the battery’s 25C rating is responsible for the low max amp readings or that the HK specs are just off??
I have some questions:
-- Would a higher C rating battery actually give me better (higher amperage readings) test results?
-- Would a higher C rating give me more lifting capacity?
-- Would a higher C rating give me more flight time?
-----
**** Here is the million dollar question… What do I have to do to upgrade the above octocopter to lift 8lb and fly for at least 15 min?
-- I like these motors, they’re smooth and I feel I can trust them… Is there anything I can do to get more lifting capacity and flight time out of them?
-- What motors would give me the results I’m looking for?
-- Would more cells make a difference?
Any advice and feedback is greatly appreciated!!!
Anthony
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