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Determine windspeed after flight
3699 39 2020-1-18
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Freerange
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I have been reading a lot about fly aways due to wind conditions. I have flown in what i thought were pretty strong winds (staying pretty close to the home point) and never had an issue. Is there a way to determine approximate wind speed based on a flight log? Whats the best program/site to use?
2020-1-18
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AntDX316
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Just run w/ the tilt sensor enabled on the bottom left to tell if the wind is getting too high.
2020-1-18
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I always use to look here after fly https://app.airdata.com/flight/62731284257e5b806ad6a0244c6a71f7/WEATHER
and I always use UAV forcast app before fly to know wind direction.


2020-1-18
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Freerange
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AntDX316 Posted at 1-18 13:22
Just run w/ the tilt sensor enabled on the bottom left to tell if the wind is getting too high.

I assume you are meaning during the flight?
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AntDX316
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Freerange Posted at 1-18 13:28
I assume you are meaning during the flight?

yeah           ,
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Paul_IA
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You actually want to think about wind speed BEFORE you fly. Especially with paper weight drone like the MM. UAV Forecast is your friend here. Also take some time and read up on wind gradients. Wind speed near the ground has nothing to do with wind speed at altitude.
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Freerange
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Paul_IA Posted at 1-18 13:29
You actually want to think about wind speed BEFORE you fly. Especially with paper weight drone like the MM. UAV Forecast is your friend here. Also take some time and read up on wind gradients. Wind speed near the ground has nothing to do with wind speed at altitude.

I understand the necessity to check weather conditions before flying, i was just curious on flights i have completed.
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DJI Stephen
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Hello and good day Freerange. Thank you for reaching out and for sharing these information. I hope that you will get the best information on what program or application will be the best for this matter from our valued DJI co pilots. In addition, the DJI Mavic Mini has a Maximum Wind Speed Resistance of 8 m/s ( Scale 4 ). Thank you and have a safe flight always.
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AntDX316
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Freerange Posted at 1-18 13:31
I understand the necessity to check weather conditions before flying, i was just curious on flights i have completed.

Airdata

https://app.airdata.com/flight/2 ... f6f2218587b/WEATHER
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jonny007
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When using UAV Forcast App I would recommend to set the height to 50 or 100 meters. Wind on ground is less important.
Another question : I've had wind warnings many times, but what do they actually say and when do they appear? I think that the position of the control sticks is related to the resulting speed and a warning is given at a certain mismatch (?). Let's say full throttle in mode P gives a speed of only 5m/s, then the (head)wind seems to be too strong and a warning appears. But does it mean that I have to descent or land immediately ? Certainly not. There is only 1 type of warning, wind or no wind. At 10 km/h the same warning as at 50 km/h. It would be interesting to know what triggers the warning and what the trigger level is....DJI any ideas ?
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lannes
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jonny007 Posted at 1-18 14:05
When using UAV Forcast App I would recommend to set the height to 50 or 100 meters. Wind on ground is less important.
Another question : I've had wind warnings many times, but what do they actually say and when do they appear? I think that the position of the control sticks is related to the resulting speed and a warning is given at a certain mismatch (?). Let's say full throttle in mode P gives a speed of only 5m/s, then the (head)wind seems to be too strong and a warning appears. But does it mean that I have to descent or land immediately ? Certainly not. There is only 1 type of warning, wind or no wind. At 10 km/h the same warning as at 50 km/h. It would be interesting to know what triggers the warning and what the trigger level is....DJI any ideas ?

According to a forum moderator, the wind warning is triggered  when the wind speed at the AC altitude exceeds 15mph/ 24 kmh.
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jonny007
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lannes Posted at 1-18 14:19
According to a forum moderator, the wind warning is triggered  when the wind speed at the AC altitude exceeds 15mph/ 24 kmh.

Does the mini has a wind gauge ?
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lannes
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Paul_IA Posted at 1-18 13:29
You actually want to think about wind speed BEFORE you fly. Especially with paper weight drone like the MM. UAV Forecast is your friend here. Also take some time and read up on wind gradients. Wind speed near the ground has nothing to do with wind speed at altitude.

Freerange is trying to understand what flight conditions the Mini can handle in reality, so that you can use apps like UAV forecast more accurately and not guesstimate what dangerous wind conditions are.

There is a wind speed tipping point for the MM, it would be good to know what this really is, is it 15mph , 20mph etc.
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Freerange
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lannes Posted at 1-18 14:26
Freerange is trying to understand what flight conditions the Mini can handle in reality, so that you can use apps like UAV forecast more accurately and not guesstimate what dangerous wind conditions are.

There is a wind speed tipping point for the MM, it would be good to know what this really is, is it 15mph , 20mph etc.

Spot on. If i could review my fights and get an understanding of the actual wind conditions i know to keep it below that for future flights. Can i review speed and angle and if full throttle can i determine approx wind speed?
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Labroides
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I have flown in what i thought were pretty strong winds (staying pretty close to the home point) and never had an issue. Is there a way to determine approximate wind speed based on a flight log?

There is no accurate way to assess wind speeds from your flight log.
But you can get an approximate idea if at some point you were to fly directly into the wind at full stick.
You know what the Mini's speed is in still air from the specs, you can see how much the wind slowed the speed, so you can get a rough idea of the wind speed.

And if anyone tries to tell you that they can from Airdata, they are wrong because it over-estimates wind strength when looking at tilt data from the Mavic Mini.

Whats the best program/site to use?
There is no best program/site to know what the wind is or will be doing where you fly.
Forecasts are just a guide and can be quite different from teh actual wind when and where you fly for a dozen different reasons.

If you want to know how the wind will affect your flight, the simple way is to test with your drone.
Don't fly off with the wind behind you and find out too late that you have a problem.
Put the drone in the air and see how it flies directly into the wind you are concerned about.
If you are planning to fly high, send the drone up toward that height and test there.

Then think about how that will affect your intended return to home.


2020-1-18
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Minnesota
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If you use the right tools you can extract out the tilt angle from the flight log and compare that to ground speed in various directions.  In each mode there is a speed to tilt angle ratio.  I've not worked it out but it can be done.
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Labroides
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lannes Posted at 1-18 14:26
Freerange is trying to understand what flight conditions the Mini can handle in reality, so that you can use apps like UAV forecast more accurately and not guesstimate what dangerous wind conditions are.

There is a wind speed tipping point for the MM, it would be good to know what this really is, is it 15mph , 20mph etc.

There is a wind speed tipping point for the MM, it would be good to know what this really is, is it 15mph , 20mph etc.

You know from the specs of the Mini that it can fly at 8 metres/sec in P-GPS mode & RTH (in still air)
And 13 m/s in Sport Mode.
So you know that against a wind of 8 m/s the drone would achieve 0 m/s in P-GPS Mode etc.
But it's not that simple.
You need to factor in distance and direction.
You won't always be flying directly into the wind.
Being able to make 5 m/s toward home won't help if you're drone is too far away.


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Freerange
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Labroides Posted at 1-18 14:51
There is a wind speed tipping point for the MM, it would be good to know what this really is, is it 15mph , 20mph etc.
You know from the specs of the Mini that it can fly at 8 metres/sec in P-GPS mode & RTH (in still air)
And 13 m/s in Sport Mode.

That sounds like what I’m looking for. Can this info be found on Phantomhelp?
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Labroides
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Freerange Posted at 1-18 15:06
That sounds like what I’m looking for. Can this info be found on Phantomhelp?

Phantomhelp will show the speed and whether you were flying at full stick.
What it can't show is whether you flew directly into the wind.
If you were flying at an angle to the wind, that complicates the issue.
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lannes
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Labroides Posted at 1-18 14:51
There is a wind speed tipping point for the MM, it would be good to know what this really is, is it 15mph , 20mph etc.
You know from the specs of the Mini that it can fly at 8 metres/sec in P-GPS mode & RTH (in still air)
And 13 m/s in Sport Mode.

As the Mini has a maximum RTH speed of 8 ms / 25 kmh/  18 mph, we shouldn't fly it in wind conditions that exceed a speed of 6ms, giving a safe margin of 2ms for the AC to get back under RTH  directly against the wind. 2ms would allow the AC to return from 2km away in 15minutes, which is half the MM battery life

Allowing for higher wind speed at altitude (6ms allowed) , this would roughly translate to a maximum wind speed at ground level of maybe 4ms/ 15kmh / 4.5mph or less

If your proficient in using sport mode then you could fly in stronger winds but you would need to factor in the extra battery drain.

Is this logic right for a thumb suck based on generous safety margins,  is a 15kmh wind speed at ground level the safe limit for the MM ?
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Labroides
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lannes Posted at 1-18 15:26
As the Mini has a maximum RTH speed of 8 ms / 25 kmh/  18 mph, we shouldn't fly it in wind conditions that exceed a speed of 6ms, giving a safe margin of 2ms for the AC to get back under RTH  against the wind. 2ms would allow the AC to return from 2km away in 15minutes, which is half the MM battery life

Allowing for higher wind speed at altitude (6ms allowed) , this would roughly translate to a maximum wind speed at ground level of maybe 4ms/ 15kmh / 4.5mph or less

It's not that simple.
Wind speed is only a small part of the equation.
You have to factor in direction and distance.
You can safely fly in fairly strong winds .... if you fly upwind and get an easy flight home with the wind.
But a short flight downwind might end up with the loss of the drone.
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lannes
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Labroides Posted at 1-18 15:34
It's not that simple.
Wind speed is only a small part of the equation.
You have to factor in direction and distance.

Agree with what your saying, I was trying to figure out a safe general rule of thumb allowing for possible scenarios and changing wind directions, a flight out against the wind might not necessarily mean a tailwind on the way back.
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Freerange
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Where are the flight logs kept on an iPhone? I see a help page for the DJI GO app but it doesnt work for DJI Fly
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Labroides
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Freerange Posted at 1-18 23:51
Where are the flight logs kept on an iPhone? I see a help page for the DJI GO app but it doesnt work for DJI Fly

Go here and you'l find instructions:
https://www.phantomhelp.com/logviewer/upload/
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Labroides
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Freerange Posted at 1-18 23:51
Where are the flight logs kept on an iPhone? I see a help page for the DJI GO app but it doesnt work for DJI Fly

Go here and you'll find instructions:
https://www.phantomhelp.com/logviewer/upload/
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the1shark
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AntDX316 Posted at 1-18 13:22
Just run w/ the tilt sensor enabled on the bottom left to tell if the wind is getting too high.

What tilt sensor ? How do I enable it ?
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AntDX316
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the1shark Posted at 1-19 01:01
What tilt sensor ? How do I enable it ?

Tilt sensor, tip sensor, attitude indicator, bank angle, etc.

I look at it often.  As well as turn your voltage battery indicator if you have it.  This way you can tell if you are pushing the motors too much if it sags hard under full power.  Anything below 3.1V is too much sag which will drive the impedance of the battery up eventually making it worse and worse.
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jonny007
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AntDX316 Posted at 1-19 01:53
Tilt sensor, tip sensor, attitude indicator, bank angle, etc.
https://www.youtube.com/watch?v=67FUSGmeg8g
I look at it often.  As well as turn your voltage battery indicator if you have it.  This way you can tell if you are pushing the motors too much if it sags hard under full power.  Anything below 3.1V is too much sag which will drive the impedance of the battery up eventually making it worse and worse.

Can you send a screenshot from the app where you see it?
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Freerange
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AntDX316 Posted at 1-19 01:53
Tilt sensor, tip sensor, attitude indicator, bank angle, etc.
https://www.youtube.com/watch?v=67FUSGmeg8g
I look at it often.  As well as turn your voltage battery indicator if you have it.  This way you can tell if you are pushing the motors too much if it sags hard under full power.  Anything below 3.1V is too much sag which will drive the impedance of the battery up eventually making it worse and worse.

Is this also on the DJI Fly app or only the DJI Go app?
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AntDX316
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I thought this was M2 Go4.  I've never used the Mavic Mini.  I'm not even sure if it exist on that.  They didn't add it because adding the chip for it to show would make it over 249g and/or the angles would be going off so much it would processor overload the main unit requiring a bigger heatsink making it over 249g or the users would see it go off so much that they think it's defective or annoying.
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jonny007
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But it doesn't matter what functions and settings are available in other apps. Perhaps these setting are in the app for Hubsan drones too. lol  
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lannes
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AntDX316 Posted at 1-19 02:25
I thought this was M2 Go4.  I've never used the Mavic Mini.  I'm not even sure if it exist on that.  They didn't add it because adding the chip for it to show would make it over 249g and/or the angles would be going off so much it would processor overload the main unit requiring a bigger heatsink making it over 249g or the users would see it go off so much that they think it's defective or annoying.

It pays to check out the sub forum before making a post
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virtual
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I see that horizon indicator in flight log, so it could be added by fw. update maybe?
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InspektorGadjet
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I've been considering one handled anemometer, since even UAV forecast cannot give accurate values depending where you are.
https://www.amazon.com/Anemomete ... ExvZ0NsaWNrPXRydWU=
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Minnesota
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InspektorGadjet Posted at 1-19 04:00
I've been considering one handled anemometer, since even UAV forecast cannot give accurate values depending where you are.
https://www.amazon.com/Anemometer-Measuring-Temperature-Windsurfing-Activities-AP-816B/dp/B07V2Z24D4/ref=lp_3206432011_1_2_sspa?s=industrial&ie=UTF8&qid=1579435196&sr=1-2-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUE4WEwwMUZXNU5HMjQmZW5jcnlwdGVkSWQ9QTA4NjAyNzQxU1RUMjNEQ0hGU1NIJmVuY3J5cHRlZEFkSWQ9QTA2MTY4NjkxS0lFWEhOSEJXUVZQJndpZGdldE5hbWU9c3BfYXRmX2Jyb3dzZSZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

There is a fancy equation to predict upper winds based on measurements at any height.  One factor is called "roughness" which can significantly change the calculation.  Below I used the roughness factor for a typical park or schoolyard with some buildings and trees within 100 meters.

The example is using a hand held anemometer held at a 2.75 meter height in "clean air" (don't let your body obstruct the flow), measuring 5 m/s, and the resultant wind profile.  

As long as you take data like this into account, at least you will have an idea of what to expect.  

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hallmark007
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No matter what you use PH Airdata UAV etc to measure wind speed you are always going to have to use common sense and the tools you actually have for flying, so check the wind when your flying can be done by using your speed in your telemetry how fast are you going is it against the wind with the wind, where are you going do you need more time to get home can the mini outpace the wind.

If you know Mavic mini can cope with 8m/s In p mode then use that, UAV app is not totally reliable and it can be very hit and miss, it’s something you don’t need for flying except to give you an idea of forecast before flying.

It’s easy to figure yourself and more reliable once you start taking notice of it it will become second nature .
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AntDX316
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lannes Posted at 1-19 03:15
It pays to check out the sub forum before making a post

Maybe people will upgrade or DJI would add it soon?  That level indicator matters a lot when I fly.
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InspektorGadjet
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Minnesota Posted at 1-19 05:26
There is a fancy equation to predict upper winds based on measurements at any height.  One factor is called "roughness" which can significantly change the calculation.  Below I used the roughness factor for a typical park or schoolyard with some buildings and trees within 100 meters.

The example is using a hand held anemometer held at a 2.75 meter height in "clean air" (don't let your body obstruct the flow), measuring 5 m/s, and the resultant wind profile.  

Nice and detailed info Minnesota!
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deathsquad
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Waste of money. The wind at ground level is different to where the drone is up in the sky. There have been times when I have flown with minimal ground level wind and I see the tree tops swaying so even with this device and a formula it wouldn't have been accurate to what I was experiencing.
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InspektorGadjet
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deathsquad Posted at 1-19 12:12
Waste of money. The wind at ground level is different to where the drone is up in the sky. There have been times when I have flown with minimal ground level wind and I see the tree tops swaying so even with this device and a formula it wouldn't have been accurate to what I was experiencing.

You are probably right, also kind of time consuming and bulky to have to carry something that still is not going to give the most accurate reading, for the issue one is trying to avoid.
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