|Feb 17, 2013, 07:09 PM|
ap/av basics #5 Lo She Blows......
It seems like wind is our nemesis when it comes to doing AV/AP especially with multicopters. I seem to get lot of questions about this, So lets talk about ways to optimize high wind flying.
Like any other RC flight, the key to wind flying is wing loading, or in case of multicopter, disk loading. for high wind, flying wing works really well for airplane while glider type does poorly. In case of multicopters, we need to get our diskloading up for best wind performance. For this, we need to use smaller prop that is really rigid for best performance. You may also need to go higher voltage to gain back some of the loss in lift. The downside is loss of flight time, but if getting that shot is very important, flight time loss can be acceptable tradeoff.
Now, I get asked about what is the best frame for windy flying. My answer is that Y6 is the best. Stacked coaxial props behaves best for yaw, and has apparent reduced disk area so handles wind and high speed the best. You do want the frame to be rigid. The downside of Y6 is reduced flight time of 10-15%. To me, that is acceptable loss of flight time. For smaller multi, I do think quad is definitely better than hexa .
Of course, if you already have to frame, you can maximize windy performance.
1) Smaller prop (that is rigid) at higher rpm is better than bigger prop. Going from 10" to 9" reduces disk area by 21% and will require higher rpm (which may need 4S power from 3S) Higher RPM is great though for stability and smaller disk area will get affected by wind less.
2)good gain setting is very important. for DJI Naza, I use low atti gain (60) and 180-200 normal gain. with this gain, you will find that the craft flies very stable and flat. this helps a lot when it comes to video.
3) good flying technique is very important. Flying with the wind is much more smoother than into the wind. some shot may require flying backward to get. descending shot is usually worse, so you may have to do ascending shot and reverse. Smart flying is very important to get the shot.
If you are setup right, you should be able to get usable shot in most flyable condition. I do find gust worse than steady high wind for good video. roofline in the afternoon is usually worst case condition for turbulence Choosing the right time can also help to avoid wind. Use common sense and you will be able to get the shot you need