Good wind resistant drone

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James Overington June 20, 2014 at 3:43am

Hi Ewen, Can you give us the battery voltage, motor kv, prop diameter and pitch of your copters? Is it possible that your props just have too low a pitch speed to handle wind? If they are designed for long duration then I presume that you have opted for the largest diameter/lowest pitch speed props possible for the motors you have to improve energy efficiency. As the wind speed approaches your pitch speed your performance will suffer. You say that the 'larger the disc, the more the wind hits it' but for any prop under normal operating parameters, the air flowing through the 'disc' actually 'hits' the under side of the prop and produces a lift force. For the wind to 'hit' the top of the disc and produce a drag force that forces the copter 'down', the prop has to have a negative angle of attack (with respect to how they would normally be used) and would essentially be blowing air in the wrong direction!
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  - Aaron Curtis June 20, 2014 at 10:39am
    
    Why 3S? Isn't it more efficient to go for higher voltage, lower kv motors?

nick rymer June 17, 2014 at 10:31am

Thank you for the input guys, I have another question. For the motors do you think it is preferable to go with say 4 larger motors or 8 regular sized motors in a x formation over under. Do either of these configurations seem to fair better against the wind?

F. C. Bearsch June 14, 2014 at 6:53pm

Agree with all of your comments... And the same as what I have experienced... I do kite surf and never thought about using the UAV also... Not sure why as now it seems obvious... I guess I have been happy with the view from the kite, and then I just fly it

James Overington June 14, 2014 at 3:25pm

I built a quad for filming kite surfing. I fly typically in 15-20 knots but have been out in up to 30 without any trouble. Larger craft typically have more mass relative to their frontal area which means that the unwanted accelerations due to wind are proportionally less. I chose a quad for simplicity and also because fewer arms is less wind resistance. My quad spans over 1m between motors and has an all up weight of 5.5kg. I think that pitch speed is often overlooked when designing for wind handling ability. Multi rotors typically have low pitched props as this allows for increased diameter for the same input power and gives better efficiency. This is fine in hover but as your horizontal speed approaches your pitch speed, you lose thrust. I would say you should design for a pitch speed twice that of the intended operational wind speed. I currently use 16x8 props which with 620kv motors on 4s gives me a max pitch speed of around 50 knots. A number of folk advocate the use of smaller props with the belief that smaller, lower mass props give better response. I am not sure that this is always the case, however it appears that I an in a minority... You can see a discussion on this topic here: http://diydrones.com/forum/topics/design-for-wind-size-matters

Søren Kuula > James Overington June 15, 2014 at 10:34am

Hi, don't you think the "smaller props people" mean smaller swept area, not lower mass?
- James Overington > Søren Kuula June 15, 2014 at 11:57am
  
  Hi Søren, I think that generally, the argument goes something along the lines of 'smaller props are easier to spin up so respond faster'. My interpretation is that the 'easier to spin up' part refers to the props rotational inertia - which is directly related to the props mass and its distribution. If you have a different take on this and how it aids in better control in high wind, then please do share it.

F. C. Bearsch June 14, 2014 at 2:29pm

I would suggest building a something with a concentrated center-mass, with a Y6 layout...

as my y6 seems to deal with wind the best

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Good wind resistant drone

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