Is there a way to get my Mavic 2 Pro to come down faster?

[klexal]

I'll try it again when I can get out again but it does seem to come down quite a bit faster with forward speed and full down. It could be the same but it feels a lot faster to me than a normal straight down landing like return to home. I could be the fear of running it into the ground before letting up on the left stick that makes it feel faster!!!!!!!!

That's because Kilrah is incorrect. Your observation is completely correct.

 

[FoxhallGH]

If you descend (down-stick) at the same time you are flying back to you (forward-stick), then the Mavic will get back to you quicker, because even though the max. descent rate is the same, you are taking a more direct route i.e. you are flying the angled 'hypotenuse' of the triangle rather than flying back at the same height, then descending from direct over-head. The shortest & quickest way between two points, is after all, a straight line ...

 

[klexal]

If you descend (down-stick) at the same time you are flying back to you (forward-stick), then the Mavic will get back to you quicker, because even though the max. descent rate is the same, you are taking a more direct route i.e. you are flying the angled 'hypotenuse' of the triangle rather than flying back at the same height, then descending from direct over-head. The shortest & quickest way between two points, is after all, a straight line ...

The descent rate is not the same. DJI have deliberately implemented firmware that restricts the vertical rate of descent of DJI drones to avoid prop wash.

Please refer to my previous comment: Is there a way to get my Mavic 2 Pro to come down faster?

 

[Probst]

If you descend (down-stick) at the same time you are flying back to you (forward-stick), then the Mavic will get back to you quicker, because even though the max. descent rate is the same, you are taking a more direct route i.e. you are flying the angled 'hypotenuse' of the triangle rather than flying back at the same height, then descending from direct over-head. The shortest & quickest way between two points, is after all, a straight line ...

Well said! As any side of a triangle is shorter than the sum of it's other two sides. Coming in "hot" would indeed be the shortest (quickest) route. Cheers

 

[FoxhallGH]

The descent rate is not the same. DJI have deliberately implemented firmware that restricts the vertical rate of descent of DJI drones to avoid prop wash.

Please refer to my previous comment: Is there a way to get my Mavic 2 Pro to come down faster?

With respect - I think you missed my point. All I'm trying to say is that you'll get your Mavic back to you sooner if you combine the descent with forward movement - as opposed to flying it back straight and level to directly overhead, then descending vertically down to the home point. I agree, the actual rate of descent isn't going to be any different due to the software limits, but the distance travelled and the time taken, will definitely be less!

To put the math's against it ... If your Mavic was at point 'X' being 30 metres high, at a distance of 40 metres from the home point 'Z' - then to fly back, you have two options:
1) You can fly horizontally from 'X' 40 metres to 'Z' , then descend from above 'Z' 30 metres - making a total distance of 70 metres travelled, or
2) You can do a controlled descent from 30 metres at point 'X' down to 0 metres at point 'Z' - travelling a total of 50 metres ... i.e. shorter = quicker ...

 

[klexal]

With respect - I think you missed my point. All I'm trying to say is that you'll get your Mavic back to you sooner if you combine the descent with forward movement - as opposed to flying it back straight and level to directly overhead, then descending vertically down to the home point. I agree, the actual rate of descent isn't going to be any different due to the software limits, but the distance travelled and the time taken, will definitely be less!

To put the math's against it ... If your Mavic was at point 'X' being 30 metres high, at a distance of 40 metres from the home point 'Z' - then to fly back, you have two options:
1) You can fly horizontally from 'X' 40 metres to 'Z' , then descend from above 'Z' 30 metres - making a total distance of 70 metres travelled, or
2) You can do a controlled descent from 30 metres at point 'X' down to 0 metres at point 'Z' - travelling a total of 50 metres ... i.e. shorter = quicker ...

Just to clarify, I completed understand what you're trying to demonstrate with trigonometry, but that's not what I'm saying. Here's my point:

because even though the max. descent rate is the same, you are taking a more direct route

The max. descent rate is not the same.The descent rate is faster when applying throttle because your drone is avoiding prop wash when descending

Here's an example. Your drone is restricted by DJI to descending vertically to 2m/s because of the limitations of prop wash, however when moving diagonally you're able to descend at 5 m/s because you're avoiding prop wash.

Your trigonometry logic is correct, but the reason that I rebuttaled your response is because your answer isn't relevant to the OP's question, which was focused on the rate of descent, not the distance to LZ.

so I started bringing her down but it would only come down at the rate of about a foot or two per second and did not have enough battery to make it back down to the launch point before running out of battery.

 

[CanadaDrone]

I tried switching to sport mode but it did not appear to increase my descent speed.

The max rate of descent is 3m/s in Sport mode, but if you apply some forward motion too you avoid the propwash that sounds so bad.

 

[LazyBird]

Descending faster would invariably mean taxing the battery more, no? So that will also eat into flying time too perhaps. Just a thought..

 

[BigAl07]

Descending faster would invariably mean taxing the battery more, no? So that will also eat into flying time too perhaps. Just a thought..

The aircraft uses LESS battery when descending because less lift is needed..... all things being equal descending using less energy.

 

[sar104]

That's because Kilrah is incorrect. Your observation is completely correct.

Have you actually verified this, or are you just guessing? If you think that adding lateral motion permits a greater vertical descent rate then you probably should take a look at your flight logs. In all the ones that I've examined, with stock parameters, I've never seen a vertical descent rate higher than 3 m/s, independent of horizontal speed.

 

[Numone]

Yeah, I think this is an illusion. I’ve never seen any difference in decent speed on my P3A over hundreds of flights in all types of weather, regardless of any forward motion. I have yet to use my MP2 but I’m sure won’t be any different.

 

[CanadaDrone]

Have you actually verified this, or are you just guessing? If you think that adding lateral motion permits a greater vertical descent rate then you probably should take a look at your flight logs. In all the ones that I've examined, with stock parameters, I've never seen a vertical descent rate higher than 3 m/s, independent of horizontal speed.

Max (stock) descent rate is 3 m/s in both S and P according to DJI. The ascent rate does get faster though, increasing from 4 m/s to 5 m/s after switching from P mode to S mode and that one is quite noticeable.

 

[paulatkin73]

Have you actually verified this, or are you just guessing? If you think that adding lateral motion permits a greater vertical descent rate then you probably should take a look at your flight logs. In all the ones that I've examined, with stock parameters, I've never seen a vertical descent rate higher than 3 m/s, independent of horizontal speed.

only way to increase descent rate is to go into params and alter it there. lateral motion does not change anything.

 

[sar104]

only way to increase descent rate is to go into params and alter it there. lateral motion does not change anything.

I know that. You know that. Others, apparently, do not.

 

[FormerMember07122019_2]

If you descend (down-stick) at the same time you are flying back to you (forward-stick), then the Mavic will get back to you quicker, because even though the max. descent rate is the same, you are taking a more direct route i.e. you are flying the angled 'hypotenuse' of the triangle rather than flying back at the same height, then descending from direct over-head. The shortest & quickest way between two points, is after all, a straight line ...

I can just hear myself when I was a young kid complaining about doing my math home work and telling my parents “why do I have to learn this stuff, I won’t ever use this stuff in the real world”. Fast forward a few years and then a lot more, and I love math.

 

[BigAl07]

I can just hear myself when I was a young kid complaining about doing my math home work and telling my parents “why do I have to learn this stuff, I won’t ever use this stuff in the real world”. Fast forward a few years and then a lot more, and I love math.

going slightly Off Topic here...

I used to have the very same thought process as a "young-in"... but back in my flight training day my instructor "let" me get us good and lost on my first Cross Country NIGHT flight. Low and behold I had to use MATH to determine where we were and how to get back on course again without any outside help. Since then I've said, "Math pretty much saved my butt." Of course my instructor knew exactly where we were and the path home the whole time but that was one heck of an AH HAA moment for me and MATH!!

 

[FoxhallGH]

Just to clarify, I completed understand what you're trying to demonstrate with trigonometry, but that's not what I'm saying. Here's my point:



The max. descent rate is not the same.The descent rate is faster when applying throttle because your drone is avoiding prop wash when descending

Here's an example. Your drone is restricted by DJI to descending vertically to 2m/s because of the limitations of prop wash, however when moving diagonally you're able to descend at 5 m/s because you're avoiding prop wash.

Your trigonometry logic is correct, but the reason that I rebuttaled your response is because your answer isn't relevant to the OP's question, which was focused on the rate of descent, not the distance to LZ.

Really interested in this and finding it educational ... So what you are saying is that DJI have a set rate of descent for the Mavic when you pull full stick-down - but - that 'set' rate of descent is ONLY relevent if the Mavic is descending vertically??? I'm no software Engineer, but that does seem to be a very difficult algorithm to even think about, let alone write?

I understand that 'prop-wash' has a parachute like effect, but surely it just means that the software will turn the prop's slower when descending vertically, than when flying down at an angle - to maintain your 3m/sec [or whatever DJI's software person set it at] descent speed. Overall, though the 'velocity' of the Mavic may be faster - the rate at which it will come down out of the sky, will not be different ...

My understanding of the OP is that the question asked is to do with getting the Mavic back to him without having to drop it short - into a bush! I still think it's relevent to talk about a strategy involving the course flown to get the drone back to you - as it's easier to do that at the time you find yourself in the situation, than to carry out a software re-write 'literally' on-the-fly to get your drone home.

 

[sar104]

Really interested in this and finding it educational ... So what you are saying is that DJI have a set rate of descent for the Mavic when you pull full stick-down - but - that 'set' rate of descent is ONLY relevent if the Mavic is descending vertically??? I'm no software Engineer, but that does seem to be a very difficult algorithm to even think about, let alone write?

I understand that 'prop-wash' has a parachute like effect, but surely it just means that the software will turn the prop's slower when descending vertically, than when flying down at an angle - to maintain your 3m/sec [or whatever DJI's software person set it at] descent speed. Overall, though the 'velocity' of the Mavic may be faster - the rate at which it will come down out of the sky, will not be different ...

My understanding of the OP is that the question asked is to do with getting the Mavic back to him without having to drop it short - into a bush! I still think it's relevent to talk about a strategy involving the course flown to get the drone back to you - as it's easier to do that at the time you find yourself in the situation, than to carry out a software re-write 'literally' on-the-fly to get your drone home.

It's not a parachute effect - it's the opposite, producing turbulent downward moving air. As the aircraft descends into that there is a reduction in lift. At worst it may generate a vortex ring state (VRS) where the aircraft cannot generate enough lift and starts to fall uncontrollably through the column of disturbed air. It's well known in the helicopter world.

Phantom 1 and Phantom 2 suffered quite badly from that condition. The cure was to add lateral motion to take the aircraft into undisturbed air. Later Phantoms and the Mavics were designed with divergent motor geometry to reduce the effect directly under the aircraft, and were also descent-rate limited in the firmware. While higher descent rates can be achieved stably without VRS by adding horizontal motion, the firmware still applies the same vertical descent speed limit independent of horizontal speed.

 

[paulatkin73]

It's not a parachute effect - it's the opposite, producing turbulent downward moving air. As the aircraft descends into that there is a reduction in lift. At worst it may generate a vortex ring state (VRS) where the aircraft cannot generate enough lift and starts to fall uncontrollably through the column of disturbed air. It's well known in the helicopter world.

Phantom 1 and Phantom 2 suffered quite badly from that condition. The cure was to add lateral motion to take the aircraft into undisturbed air. Later Phantoms and the Mavics were designed with divergent motor geometry to reduce the effect directly under the aircraft, and were also descent-rate limited in the firmware. While higher descent rates can be achieved stably without VRS by adding horizontal motion, the firmware still applies the same vertical descent speed limit independent of horizontal speed.

i tried my mavic 2 with up to 12 m/s ascent / descent rate and it was stable. 12m/s is like a speed of a stone falling from the sky to an observer , so, a safe setting i think is around 8 m/s - i kept that for sport, and for P mode left 4 m/s down and 5m/s up. seems to work fine this way.

 

[sar104]

i tried my mavic 2 with up to 12 m/s ascent / descent rate and it was stable. 12m/s is like a speed of a stone falling from the sky to an observer , so, a safe setting i think is around 8 m/s - i kept that for sport, and for P mode left 4 m/s down and 5m/s up. seems to work fine this way.

Did you check the flight log at 12 m/s? It would be interesting to see if the magnitude of the pitch and roll excursions is any larger than at 3 m/s.