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Old May 01, 2015, 09:01 PM
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Wheelbase, prop size, stability question

I have built a quad with a wheelbase of 515mm. I have 610 kv motors, 12 x 3.8 props and 20A ESC's. Weight is 1540 with camera, gimbal and 5200 3s battery. I am using a NAZA controller. I am getting great flight times but I am having some issues with stability. I have tried to optimize the gains but it seems to fly about the same no matter where I set them. It seems really affected by the least wind. With my other multirotors, I have been able to raise the gains until it stars oscillating and then back off a bit. this one never really oscillates.
I am wondering if it would help to go to smaller props or longer arms.
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Old May 01, 2015, 10:24 PM
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Try 4s. A little more weight and RPM. Both could assist with the stability.
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Old May 01, 2015, 10:56 PM
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Quote:
12 x 3.8 props
Slow Fly props ? (SF)

Along with Pats suggestion, also try the 12X4.5 MR (MultiRotor). They're a little stiffer and may change the way it behaves.
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Old May 02, 2015, 01:57 AM
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Good call. Try that first.
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Old May 02, 2015, 07:24 AM
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Originally Posted by PatR View Post
Try 4s. A little more weight and RPM. Both could assist with the stability.
I have tried a 4s 2450mah battery. It does seem to help some but it is still affected by wind too much. I will try adding a larger 4s battery.
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Old May 02, 2015, 07:26 AM
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Originally Posted by William A View Post
Slow Fly props ? (SF)

Along with Pats suggestion, also try the 12X4.5 MR (MultiRotor). They're a little stiffer and may change the way it behaves.
I have Carbon fiber props on it now which are very stiff. I will try the 12x4.5 MR props as you have suggested. Do you have a recommended source for these?
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Old May 02, 2015, 10:33 AM
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Originally Posted by PatR View Post
Try 4s. A little more weight and RPM. Both could assist with the stability.
I just tried another flight with the 4s 2450 battery but I added another 200g of weight. It did fly smoother however there is no wind at all right now so it was not a perfect test. I have ordered a 4000mah 4s battery which is the largest that will fit in the shell. I will post results when I have tried that.
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Old May 02, 2015, 01:55 PM
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Old May 02, 2015, 09:44 PM
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Quote:
Originally Posted by syotr View Post
I just tried another flight with the 4s 2450 battery but I added another 200g of weight. It did fly smoother however there is no wind at all right now so it was not a perfect test. I have ordered a 4000mah 4s battery which is the largest that will fit in the shell. I will post results when I have tried that.
The high prop surface area and reasonable low weight will make it more likely to more around in the wind.

If you tune in no wind, the PIDs could be a bit high for wind. I have never used a NAZA but have found on a few other flight controllers on quads with large props that lower P values a bit and increasing I values often helps with windy conditions. In summer it gets windy around home so I'm regularly flying in 30km/hr winds that gust up to 45km/hr.

Angled arms or motor mounts can help with stability in windy environments.
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