Scenario 2: low battery, long distance, and the wind shifts

[jamesw]

Have a look at this video. It may answer the question:

I'll check the video after work. I'm guessing the answer isn't black and white? if so, don't hold back, share the info!

 

[leonardolisboa]

I'll check the video after work. I'm guessing the answer isn't black and white? if so, don't hold back, share the info!

As per the video, sports mode is 10% less efficient.

 

[Porto]

Have a look at this video. It may answer the question:

The problem with the video was that the guy did the GPS mode with Obstacle Avoidance (OA) on. If he did it with OA off, the difference between GPS mode and Sports mode very likely is even more than 10%.

Based on my experience and from reading others that do long distance run, the most efficient is to use GPS mode with OA off. Without wind, it would be about 50kph (31mph). That is if you didn't do any parameter changes to the GPS mode speed (those who doesn't know what parameter changes, you are fine).

Don't rely on (unmodified) RTH speed. If the Smart RTH kicked in due to remaining battery power, once the drone is facing the Home Point push the right stick (as most people use the more common Mode 2) forward with OA off then cancel RTH to kill the annoying beeps. If RTH kicked in due to lost connection, once you regain connection, do the same.

 

[DiverDan]

As per the video, sports mode is 10% less efficient.

May be true for battery consumption but that extra boost from sport mode may be what you need to combat the wind. If you are at a near stand still due to wind, you may need sport mode to make headway.

 

[Marco Cantieni]

To my experience Sport mode is more efficient at high winds. BUT don‘t go to max speed. Once the props rev higher it cost more battery juice than normal mode. Sportmode also switches sensors off what saves dome energy additionally. Needless to say that recording should be avoided.

 

[Kilrah]

Sportmode also switches sensors off what saves dome energy additionally. Needless to say that recording should be avoided.

That is completely insignificant.
Stupid to advise not to record becasue that's one less help you're not getting in case you don't make it.

 

[Marco Cantieni]

If you 100% sure the bird won‘t make it back then look for a spot to land, first on the map than with Cam down. If once you‘ve found a spot move the bird exactly above that spot so that that a stick down is all that‘s needed to land. Bevor you do that set the homepoint to the birds position. That avoids a RTH to the wrong location in case you lose connection while you land.

 

[Marco Cantieni]

That is completely insignificant.
Stupid to advise not to record becasue that's one less help you're not getting in case you don't make it.

Please explain why recording, compressing is not significant? Most long distance record trials have recording off in order to safe battery juice. If this is not the case I would love to hear why.

 

[mw174620]

In scenario 2, your DJI drone is over a mile away. The Home indicator (red yellow and green line with the H) indicates you have enough battery remaining to return.

Then the wind shifts, and you find that your return velocity is limited, and you may or may not have enough battery for the return.

What things will be on your mind, and in what priority, to deal with this situation. How can you prepare yourself and your equipment to deal with this possibility?

This is an open ended discussion that I hope some of you will contribute your own ideas and thoughts.

In my opinion, you look for a safe and open landing spot, put the drone down and check the map. Then head to that spot as quick as possible. If you can't find, you might have enough to get it back up into the air long enough to hear or spot it.

 

[Kilrah]

Most long distance record trials have recording off in order to safe battery juice. If this is not the case I would love to hear why.

Becasue people who don't know think it makes a difference, they never ckecked whether it did and how much if anything.
A Mavic in fast flight draws about 200W. The expected extra consumption of a camera when recording would probably be <5W. That's 2.5% difference, which is insignificant.

Now when actually measured - there is no difference at all.



Since the Mavic does live transmission the encoders likely run all the time and recording just starts/stops dumping to disk.

 

[tracer bullet]

set the homepoint to the birds position.

That's a good idea. I have thought to myself a number of times, while flying and still with a strong battery, "hmm if I had to land here, what would I do?". I've always thought I could simply land and cut the rotors, then get myself to that point to either scoop it up or if needed turn the rotors back on to get it back after I'd gotten much closer.

I love the replies about how not to get into this situation - "Don't fly that far with that little battery" is the most useless answer possible here, I think folks are aware of what should be done. But it's still a great thought exercise, since there are not only environmental factors out of your control but also potentially mechanical or software issues that you can't control. "What if" one of the battery cells died and you had an emergency on your hands? It's good to think of what you'd do in an emergency, if one were to ever come up.

 

[Marco Cantieni]

Since the Mavic does live transmission the encoders likely run all the time and recording just starts/stops dumping to disk.

Thanks very much for your plausible explanation

 

[mavicn00b]

Never rely on RTH solely. When I was a newbie I did and the darn thing decided to auto land in some guys back yard at 15%. It has only about 500m to go and could have made it home but I didn't know any better at the time. I was on FW 550 at the time and I believe they had the force landing override disabled in that FW.

Use the RTH feature to allow the craft to set the optimal flight path and then take control of it with or without sports mode depending on the wind.

When it goes critical, be prepared to go left stick up to override the force auto land.

I've seen these been flown 60-120 seconds past 0% so it might be worth sacrificing a battery to save the craft it came down to the wire.

 

[Kilrah]

I've seen these been flown 60-120 seconds past 0%

But they can also turn into a brick at 5%, so you've got to be aware that you're playing lottery there, you may be sacrificing your aircraft by trying to push it when you had an opportunity to land.
And never overfly anything you wouldn't want to drop a brick on anytime <10%.

 

[Mission North]

In drone flight most of the power is used in fighting gravity and only a small percentage goes to move the machine. The faster you fly the shorter the time and less energy you use fighting gravity. Also, when flying into a headwind, the slower you fly the longer you have to stay in the air and therefore the more air you will have to fly through. Flying slower will keep you in the air for longer - up to a point. Though the Mavic apparently uses the least power moving at an air speed of about 15mph. But we are not trying to stay in the air for more time, rather to travel the longest distance over the ground before the battery goes flat.

On the other hand... Time slows down as you approach the speed of light. Time flies when you're having fun. Therefore the slower you go the more fun you'll have.

 

[chris765_2000]

In scenario 2, your DJI drone is over a mile away. The Home indicator (red yellow and green line with the H) indicates you have enough battery remaining to return.

Then the wind shifts, and you find that your return velocity is limited, and you may or may not have enough battery for the return.

What things will be on your mind, and in what priority, to deal with this situation. How can you prepare yourself and your equipment to deal with this possibility?

This is an open ended discussion that I hope some of you will contribute your own ideas and thoughts.

I'd hit the return to home button as I believe the drone will calculate the speed at which it needs to fly so as to make the most efficient use of the battery. I crashed my drone in the Hudson a few months ago because I decided to fly around for a minute or so after receiving a warning to Return Home. I was about 4 miles away. I flew back full throttle and crashed 2000 feet from shore. In retrospect, I should have let the drone fly itself back.

 

[Kilrah]

I'd hit the return to home button as I believe the drone will calculate the speed at which it needs to fly

That is not correct, it will always take longer than what you can do manually in sport mode.

 

[CyberNate]

Have a look at this video. It may answer the question:

They are flying with a strong tail wind. Mavic speed is limited to ground speed of around 40mph. If you have 10 mph tail wind, the air speed is only 30. Sport mode is very inefficient if flying into the wind, but going with the wind is actually more efficient.

 

[mlash]

Here is a video of the same scenario except I flew out with the wind and the wind was way too strong (20+ mph) to return the way I had it set up. It was a good test to learn that I could recover and I now have this under my belt if I ever get in any trouble! Also, if you set your failsafe to hover when it gets to critical battery it will just land where it's at.

 

[m0j0]

I'd hit the return to home button as I believe the drone will calculate the speed at which it needs to fly so as to make the most efficient use of the battery. I crashed my drone in the Hudson a few months ago because I decided to fly around for a minute or so after receiving a warning to Return Home. I was about 4 miles away. I flew back full throttle and crashed 2000 feet from shore. In retrospect, I should have let the drone fly itself back.

No and no... at 4 miles away your best bet would have been to heed the battery warning and fly back when prompted. That alone would have increased your chances of getting it back significantly. RTH is a tool that has worked 100% of the time for me but I truly understand how it works. If you do hit RTH push the right stick forward to increase the RTH speed... or fly it back with the radar and forward sensors off.