Wind Performance — Coax vs. Flat

[Aldorello]

Hello everyone!
I opened this thread because researching for the best UAV setup in order to fly in particularly windy environments (37mph - 60kmh) I have been reading many contrasting opinions: there is who say the most important thing is the platform layout (X8/hexa/octo) and someone is more focused on motors Kv and propeller size.

So, what's in your opinion the best combination to carry a 2kg payload and have a 15 min flight time in windy, gusty conditions and why?

 

[moonpie57108]

Other factors like frame cross section are going to help/hurt, but my smaller faster props seem to get pushed around less than my bigger slower prop quads. How much of this is reducing rotor size? and how much of it is the small props responding faster, not sure.

Higher KV that I picked is simply because of the smaller props nothing else. If I had the option for say 500kv at 16" or 280kv at 20" for the same thrust (random numbers), the 20" is going to give better endurance but I would think the 16" would handle better in winds that strong.

At that wind speed you might also need to push your Thurst to Weight ratio as high as you can or you will risk losing your drone when it cannot over come the wind speed. 2:1 being a cited minimum, I might aim for a minimum of 3:1 or 4:1 if you could pull it off. Even at 15-20 mph near the ground can generate much higher gusts once you are up in the air. If you are sustained 30-40 mph, you could guess your gusting 45-50+ mph up off the ground. You could find yourself in a situation of not being able to go up wind to get home. That said, always launch into the wind if you can so that your coming home flight is with the wind. Your battery and multirotor may thank you later.

As a second point of reference, WooKong-M flight controller I think notes max wind resistance of around 20 mph. Food for thought.

 

[violetwolf]

Perfect post by Moonpie. Pretty much nails it.

The smaller the wheelbase the better in wind for sure. IE: X8 ... The trade-off is they are a little "twitchy" compared to a large octo, but this quick to react characteristic is what makes them better in wind. (Just to be aware that there is always a trade-off)

Pixhawk/APM is the way to go with FC too. The X8 config is prone to "pendulum effect" and most I've seen online with this issue are using DJI controllers. And try to keep the gimbal as short as possible.

 

[MadMonkey]

And try to keep the gimbal as short as possible.

Yeah. Long moments with a lot of weight on the end are a bad idea in any situation when it comes to these things, unless you're flying straight up and then coming straight down.

 

[Old Man]

Disc area hammers on a flat anything, The more disc area the more susceptible it is to wind displacement. A well designed X8 can shut down the top or bottom motors during high wind conditions and still remain about 65%-70% functional.

 

[fltundra]

You will see improvements with a quad or X8 when using ESC's with active braking in high winds.

 

[Old Man]

You will see improvements with a quad or X8 when using ESC's with active braking in high winds.

Only up to a point. That disc area gets large enough you can't obtain enough from the braking to save the day. Google FLARES Multirotor.

 

[safety3rd]

X-8 has always been better in the wind, hex, and octa become like a kite.