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Wind Speed calculation
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Seevee
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Flight distance : 51378 ft

United States
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Has anyone devised a simple formula to determine the wind speed where the drone is flying?

Something like, fly north for x time, then west for x time, then east for x time and south for x time. And note the distance each time to determine ground speed average for each leg. And then plugging into a formula to determine wind? Could also determine direction of the wind if we had heading and track info.

Anyone come up with this?

Seevee
Phantom Advanced
2018-1-3
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PeteHB
Second Officer

France
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For a reasonable approximation just fly directly into the wind until you get a consistent or good average wind speed then fly a reciprocal route noting again the average wind speed take the 1st reading from the 2nd and that will give you the current wind speed.
2018-1-3
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solentlife
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PeteHB Posted at 2018-1-3 08:34
For a reasonable approximation just fly directly into the wind until you get a consistent or good average wind speed then fly a reciprocal route noting again the average wind speed take the 1st reading from the 2nd and that will give you the current wind speed.

Exactly ...

The Speed indicated on your GO / Litchi is GPS derived and is GROUND SPEED. Therefore as PeteHB says ... fly with wind and against wind - the difference is wind speed.

No need to do squares or anything else.

Don't forget also that wind speed alters with height above ground .. so if you want a meaningful FLIGHT solution - maintain  a constant height in those runs ...

Nigel
2018-1-3
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AlanHd
Captain
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United Kingdom
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I just normally switch to ATTI mode and see what speed the drone accelerates to without any input.
2018-1-3
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bob37
First Officer
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United States
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I just use https://www.uavforecast.com/#/, which gives wind speed and direction at whatever altitude you ask for.  Sometimes it will be almost calm at the ground, but 30 mph at 300 feet, which is my RTH altitude.
2018-1-3
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solentlife
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AlanHd Posted at 2018-1-3 08:57
I just normally switch to ATTI mode and see what speed the drone accelerates to without any input.

??

And where do you think the speed indication is coming from on your display ?

ATTI or GPS mode makes no odds to this question. The speed is still GPS derived by calcualting between successive positions ..

Nigel
2018-1-3
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AlanHd
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solentlife Posted at 2018-1-3 09:24
??

And where do you think the speed indication is coming from on your display ?


I know that but it just saves me having to fly with the wind and against the wind to find the difference.
2018-1-3
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A CW
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PeteHB Posted at 2018-1-3 08:34
For a reasonable approximation just fly directly into the wind until you get a consistent or good average wind speed then fly a reciprocal route noting again the average wind speed take the 1st reading from the 2nd and that will give you the current wind speed.

This is exactly what I do. Also note that wind direction and speed can change in a split second. The wind is therefore a variable and as it's not static any formulae will always be subjective and approximate.
2018-1-3
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Popie
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I do like Alan, just go to alt you want to and move 200 feet in to the wind ( just so I can see it go by ) switch to atti mode let it go and watch the speed till it quits climbing. Might not be the exact speed? but it is what the wind is pushing on your copter with I think.
2018-1-3
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solentlife
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AlanHd Posted at 2018-1-3 09:31
I know that but it just saves me having to fly with the wind and against the wind to find the difference.

OK ... I see where you are coming from now ... you use the DJI stated max speed (16m/s) and just take the difference you actually get max throttle .. EDIT : That was a quick post and should have been full forward stick ...

mmmmmm given the variability of wind speeds anyway - its as good as any ..

I automatically use the Into and With wind scheme because of the Need for Speed stuff I did ... still waiting for someone to beat my Parkjet 2 at 222kph ... it was a group that used the same model and we all tried to get max out of it ... I hit 222 and that seemed to be about as much as we could get .. I did put together a twin prop version which calculated out at over 300kph ... but we couldn't get the darned thing to launch straight !
My T45 with pusher was over 200kph as well ...

Speeds were verified by two way runs and also Pitot Tube ...

Nigel
2018-1-3
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Genghis9
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Considering that winds are usually always variable, especially when around any kind of obstruction or buildings, why would you waste the battery power/time to determine this?  The local forecast is as good as any if you are concerned with operations or attempting to fly any distance.  
Low level winds are not reliable and or consistent enough to factor in safely for any flight benefits or detractions, again the forecast or local weather station readings are just as useful or more so.
2018-1-3
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solentlife
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Aw Genghis ..... its all a bit of fun ..

Nigel
2018-1-3
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AlanHd
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solentlife Posted at 2018-1-3 10:57
OK ... I see where you are coming from now ... you use the DJI stated max speed (16m/s) and just take the difference you actually get max throttle ..

mmmmmm given the variability of wind speeds anyway - its as good as any ..

That’s some seriously impressive speed, I’ve never flown fixed wing so compared to my first drone which was a hubsan h501s my my P4P seams fast, now I’m realising I’m still in the slow lane lol
2018-1-3
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solentlife
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Just as examples ....

180kph T45 as it did that low close flyby !



Here is a slow run of the Parkjet ... only 183kph



I did manage a 230kph run but no-one to verify the result ... so my PKJ record at 222kph stands.

The ET Pitot tube system means that its not necessary to do with and against wind as it measures air pressure static vs dynamic.

Nigel
2018-1-3
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AlanHd
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solentlife Posted at 2018-1-3 12:01
Just as examples ....

180kph T45 as it did that low close flyby !

Impressive, it looked like you had your hands full in the second video.
2018-1-3
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G Davidson
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Without putting a figure on the wind speed, I use the attitude indicator on the radar display (bottom left of DJI Go) and hover. If there’s a lot of pitch/roll, you know it’s working against a stiff wind to hold station. Not an exact method but useful to get a feel for conditions at altitude. To determine the wind direction, I yaw the craft around until I see the maximum pitch forward and minimum roll which means it’s facing directly into the prevailing wind.
2018-1-3
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Labroides
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solentlife Posted at 2018-1-3 10:57
OK ... I see where you are coming from now ... you use the DJI stated max speed (16m/s) and just take the difference you actually get max throttle ..

mmmmmm given the variability of wind speeds anyway - its as good as any ..

OK ... I see where you are coming from now ... you use the DJI stated max speed (16m/s) and just take the difference you actually get max throttle ..
He doesn't use any joystick input (and throttle would make his phantom ascend anyway).
He simply sees how fast the wind will push the Phantom when it's hovering in atti.
Phantom drifts @ 1m/s = gentle breeze   
Phantom drifts @ 10 m/s = a wind you need to factor into your flight planning.
2018-1-3
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Labroides
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bob37 Posted at 2018-1-3 09:18
I just use https://www.uavforecast.com/#/, which gives wind speed and direction at whatever altitude you ask for.  Sometimes it will be almost calm at the ground, but 30 mph at 300 feet, which is my RTH altitude.

Forecasts are only good for general planning but should not be relied on to indicate actual conditions for a specific location.
There are many sources of possible error and the forecast could be very different from actual conditions on your flight site.
2018-1-3
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Dockater
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Has anyone devised a simple formula to determine the wind speed where the drone is flying?   

This was the original question.

The simple answer has been stated several times, no need to make it complicated.

Fly to where you want to do the check, stop all control input, switch to “atti” mode, read off the speed on the controller display. That is all.

Weather forecasts, wind speed measuring devices are all well and good in a stable weather situation, but where land and water come together, in the mountains or irregular landscapes and unstable weather conditions the wind speeds over just a few meters horizontal or vertical may change enormously, in the middle of a lake, in a valley, at the top of a cliff or around the corner of a building.
2018-1-3
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Genghis9
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solentlife Posted at 2018-1-3 11:30
Aw Genghis ..... its all a bit of fun ..

Nigel

For that I sincerely apologize...in fun by all means, to learn by all means, enjoy!  
I guess I was thinking to literally sorry!
2018-1-3
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bob37
First Officer
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Labroides Posted at 2018-1-3 15:49
Forecasts are only good for general planning but should not be relied on to indicate actual conditions for a specific location.
There are many sources of possible error and the forecast could be very different from actual conditions on your flight site.

uavforcast.com is for wherever your computer is.  If it is close to the flight site, it is quite good.  I set the limit at 300 feet (RTH) very low (12 mph) so that if it is even 50% off, i am okay to get home.  What i find interesting is a 35 mph wind at 300 feet may be almost calm at ground level.  I wonder if that is the occasional "fly-away" comments we see in the forum.  I am a chicken setting it so low, but my P3A always comes home (over 200 times).   
2018-1-3
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Seevee
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Dockater Posted at 2018-1-3 16:28
Has anyone devised a simple formula to determine the wind speed where the drone is flying?   

This was the original question.

That really sounds like a good solution. I've never flown in ATTI mode, so need to try this. Suspect it would also give you wind direction, by seeing the course made good, correct?
2018-1-3
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Labroides
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bob37 Posted at 2018-1-3 17:31
uavforcast.com is for wherever your computer is.  If it is close to the flight site, it is quite good.  I set the limit at 300 feet (RTH) very low (12 mph) so that if it is even 50% off, i am okay to get home.  What i find interesting is a 35 mph wind at 300 feet may be almost calm at ground level.  I wonder if that is the occasional "fly-away" comments we see in the forum.  I am a chicken setting it so low, but my P3A always comes home (over 200 times).

a 35 mph wind at 300 feet may be almost calm at ground level.

calm on the ground but 35 mph at 300 feet is a bit more extreme than you'll find most of the time but the wind up high is usually stronger than down on the ground.
I wonder if that is the occasional "fly-away" comments we see in the forum.
It's very common.
Every week we see cases of people flying high and going downwind in conditions that make it impossible for the Phantom to return.
Here's one from earlier today: https://forum.dji.com/forum.php?mod=viewthread&tid=127548
The explanation is in post #19.
2018-1-3
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solentlife
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Labroides Posted at 2018-1-3 15:47
OK ... I see where you are coming from now ... you use the DJI stated max speed (16m/s) and just take the difference you actually get max throttle ..
He doesn't use any joystick input (and throttle would make his phantom ascend anyway).
He simply sees how fast the wind will push the Phantom when it's hovering in atti.

Yes the post - I have gone back to edit ... was made quickly and I put throttle instead of full right forward stick ... problem of being a wide ranging RC flyer !

mmmm stopped and let it drift ... I can see that ... wasn't immediately obvious in his post .. but accepted.

Nigel
2018-1-4
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R&L Aerial
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AlanHd Posted at 2018-1-3 08:57
I just normally switch to ATTI mode and see what speed the drone accelerates to without any input.

I do the same, after switching to atti I observe the drift speed and direction, it’s not 100% accurate but if your quad is drifting at 15 mph it’s safe to assume that the wind speed is around 15 mph??
2018-1-4
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solentlife
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Genghis9 Posted at 2018-1-3 16:41
For that I sincerely apologize...in fun by all means, to learn by all means, enjoy!  
I guess I was thinking to literally sorry!

Hey ... no prob ... why apologise ??

Nigel
2018-1-4
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solentlife
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Its funny how simple solutions get missed ..

Having spent so long doing Speed stuff ... pylon racing and all that - stopping a Drone and letting it drift is simple !!

Old habits die hard ...

Nigel
2018-1-4
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Genghis9
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solentlife Posted at 2018-1-4 04:21
Hey ... no prob ... why apologise ??

Nigel

Yeah...I just didn't want to come off sounding like a jerk...you know like how some others can do
2018-1-4
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solentlife
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Lets just say that some on here like to portray some others as 'jerks' ............

No prob Genghis ... hope you have a great 2018 .. and many good flights.

Nigel
2018-1-4
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