Most battery efficient speed to cover a distance

[F00Man]

I have a Mini 2 drone and am wondering what is the most battery efficient speed to fly:
- horizontally from point A to point B
- vertically from altitude A to altitude B

,regardless of the time it takes to cover that distance, and in the same weather conditions.

CINE mode at max speed of 6m/s flies 300m in 50 seconds, and consumes x1% battery
NORMAL mode at max speed of 10m/s flies 300m in 30 seconds, and consumes x2% battery
SPORT mode at max speed of 16m/s flies 300m in 19 seconds, and consumes x3% battery

How different are the values of x1 ,x2 and x3, and what is a short explanation of these differences ?

Thanks for your time

Math is hard...just sayin'

 

[GadgetGuy]

Probably the same shape. But, at least for the P3 and MP, the scale is different. I.e. the P3 or MP max speed is less or equal to the peak efficiency.

Correct. The top speed in P mode was roughly 31 mph, which was also the most efficient for covering maximum distance per battery. If there was an S mode capability, it was equally efficient as long as the drone was flown at the same top 31mph speed of P mode and no faster. Since most long distance fliers preferred the ease of simply maintaining max throttle with full right stick, even on a rubber band, P mode was invariably the chosen flight mode.

 

[BudWalker]

Correct. The top speed in P mode was roughly 31 mph, which was also the most efficient for covering maximum distance per battery. If there was an S mode capability, it was equally efficient as long as the drone was flown at the same top 31mph speed of P mode and no faster. Since most long distance fliers preferred the ease of simply maintaining max throttle with full right stick, even on a rubber band, P mode was invariably the chosen flight mode.

Yeah, I've been looking for some of those old posts. But, they seem to have been removed - at least I can't see them.

 

[BudWalker]

Correct. The top speed in P mode was roughly 31 mph, which was also the most efficient for covering maximum distance per battery. If there was an S mode capability, it was equally efficient as long as the drone was flown at the same top 31mph speed of P mode and no faster. Since most long distance fliers preferred the ease of simply maintaining max throttle with full right stick, even on a rubber band, P mode was invariably the chosen flight mode.

So is it the case with the MP that in Sport mode it's possible to exceed the peak efficiency pitch? I thought that max pitch was less than peak efficiency pitch; even in Sport mode.

Coincidently, I was thinking about trying to determine the peak efficiency pitch for my DJI FPV. Not so obvious, to me at least, what is the easiest way to gather the data.

 

[Alan Mac]

I don't believe that the mode you are in effects efficiency of the drone. It's not like you are changing gears or anything. Speed is speed. Different modes just give you reduced throttle output.

Looking at the Airdata Data for the Mavic Pro...
At 10 mph you can go approx 4.5 miles on a pack.
At 20 mph you can go approx 7 miles on a pack.
At 30 mph you can go approx 7.5 miles on a pack.
At 40 mph you can go approx 8 miles on a pack.

So, at least on the Mavic Pro, it looks like the faster you go, the more ground you can cover on a power pack.

This makes sense to me. If you hover, you get zero miles to a battery. Go very slow, and you don't get much more. It would seem logical to me that the faster you go, the greater the proportion of power used in actually driving forward, rather than just staying in the air.

 

[Grazuncle]

This makes sense to me. If you hover, you get zero miles to a battery. Go very slow, and you don't get much more. It would seem logical to me that the faster you go, the greater the proportion of power used in actually driving forward, rather than just staying in the air.

I understand what you're saying but hovering in whatever mode will use the same energy.. Hovering in sport mode will not use more energy..
However moving through the air and efficiency is what is the aim of the post. I don't know of any linear efficiency in my engineering past.
I'd like to be proved wrong. LOL

 

[Alan Mac]

I understand what you're saying but hovering in whatever mode will use the same energy.. Hovering in sport mode will not use more energy..
However moving through the air and efficiency is what is the aim of the post. I don't know of any linear efficiency in my engineering past.
I'd like to be proved wrong. LOL

How about electric motors? Aren't they equally efficient throughout their power range?

 

[Grazuncle]

How about electric motors? Aren't they equally efficient throughout their power range?

not in my experience with passenger lift motors (elevators in USA) Either AC, Thyristor controlled AC or DC.

No doubt efficiencies have improved since I left the industry; not least through better bearing surfaces, lubrication, lighter materials.. but still nothing linear in return.

I would however, like the OP, like to be able to get to that far distant place, in sport mode, and then actually start recording, than crawl there. Regarding experiences reported in YT videos they mostly comment that Sport mode uses up un-equal energy compared to other modes if you need distance. Not empirical data I know; just their experiences

There must be someone who can meter actual live usage under different loading.. (i.e. sport vs normal)

 

[GadgetGuy]

I understand what you're saying but hovering in whatever mode will use the same energy.. Hovering in sport mode will not use more energy..
However moving through the air and efficiency is what is the aim of the post. I don't know of any linear efficiency in my engineering past.
I'd like to be proved wrong. LOL

Flying the same speed in any mode capable of that speed will use the same energy, not just hovering.

 

[GadgetGuy]

So is it the case with the MP that in Sport mode it's possible to exceed the peak efficiency pitch? I thought that max pitch was less than peak efficiency pitch; even in Sport mode.

Coincidently, I was thinking about trying to determine the peak efficiency pitch for my DJI FPV. Not so obvious, to me at least, what is the easiest way to gather the data.

Yes, any time Sports mode exceeds 31mph, it is increasing the forward pitch to do so, reducing peak efficiency of the aircraft. P mode prevents exceeding that pitch, which is why the max speed declines into a headwind.

Just fly forward in a very large orbit at different speeds to see what speed the greatest distance achievable occurs at. DJI might also know, if you can get to the right engineer!

 

[Alan Mac]

Flying the same speed in any mode capable of that speed will use the same energy, not just hovering.

That's true. My point was, it uses x Watts to hover, and you're going nowhere. So effectively x Watts is "wasted power" in regards to moving forwards.

Moving will use x+y Watts, with the y component being the proportion contributing to actually moving forwards. The faster you move, the greater y becomes.

 

[GadgetGuy]

Yeah, I've been looking for some of those old posts. But, they seem to have been removed - at least I can't see them.

I think they are still around in the modded section that requires checking a box under your profile to be able view. However, I haven’t searched for them in ages, so they might have been archived away. I copied out all relevant posts back when I was actively using those older aircraft in the days of the Wild West!

 

[sar104]

It was pretty well established that the Phantom 3 series had maximum distance at maximum speed. It's been so long that the posts supporting this are no longer available. I believe this was also shown to be true of the Mavic Pro and the Phantom 4. And, I suspect this true for the other DJI platforms since and after the Phantom 3.

It was discussed in a phantompilots thread:

Physics of Drones

Give a drone to a physicist and he/she is likely to want to know how it works. Those with some science background might like to see http://homepages.abdn.ac.uk/nph120/meteo/DroneFlight.pdf. The article includes power consumption for hovering, rising and moving forward, estimated from mechanics...

phantompilots.com

and

Physics of Drones

Give a drone to a physicist and he/she is likely to want to know how it works. Those with some science background might like to see http://homepages.abdn.ac.uk/nph120/meteo/DroneFlight.pdf. The article includes power consumption for hovering, rising and moving forward, estimated from mechanics...

phantompilots.com

 

[JackL]

There must be someone who can meter actual live usage under different loading.. (i.e. sport vs normal)

I' suppose I could fly dead straight out to sea at the same altitude until it wants to come home in each mode on a day the wind is calm and consistent. I'm curious now myself but I've flown like this a whole lot and am pretty sure N will win. At least on the MA2 I fly.

 

[RC_Adik]

This may be a repeatable method for determining flight time & distance. A little old but should work.

 

[GadgetGuy]

That's true. My point was, it uses x Watts to hover, and you're going nowhere. So effectively x Watts is "wasted power" in regards to moving forwards.

Moving will use x+y Watts, with the y component being the proportion contributing to actually moving forwards. The faster you move, the greater y becomes.

However, there is a sweet spot to the y component that optimizes distance, which is independent of the selected speed mode.

 

[Grazuncle]

I'd like to see some science in all of this. LOL

We all have our own ideas and experiences.. (myself included) but some actually repeatable testing would answer this efficiency dilema. Is more energy put into higher speed giving us a linear return?

someone mentioned hovering is wasted energy.. it would seem that way but hover energy is still required in drones whatever manoeuvre we require otherwise it would just fall to the earth.. Aeroplanes can rely on forward only movement as they benefit on the uplift function of negative pressure of the wing profile. Drones don't have that and the upward thrust is always necessary.. unless you don't want to fly at all... LOL

interesting thread

ps.. in a referred above YT video a point on testing came up.. different batteries hold different charges... So I'm guessing that you had better keep to the same battery.. testing would all relate then. Or you would have to use many batteries to find the mean.

 

[Grazuncle]

looking for science..

Found this from the UK government Department of Transport on driving electric cars efficiently

https://www.energysavingtrust.org.uk/sites/default/files/reports/Efficient%20driving%20in%20electric%20and%20low%20emission%20vehicles.pdf

part which is interesting quote:
3. Watch your speed High speeds increase energy consumption in EVs more than they increase fuel consumption in conventional vehicles. Typically in a conventional vehicle, the most efficient speed (and therefore maximum MPG) is achieved at approximately 40 – 50 mph, but the most efficient speed for EVs is lower than this. The reason for the higher energy consumption at speed is that air resistance (drag) increases by the square of the vehicle speed. With conventional vehicles this effect is somewhat countered by the fact that vehicles are more efficient in higher gears, but with EVs the countering effect of gears does not come in to play. This is why electric cars are well suited to city driving where speeds are often lower.

So it would seem then that air resistance is not linear to speed

 

[sar104]

looking for science..

Found this from the UK government Department of Transport on driving electric cars efficiently

https://www.energysavingtrust.org.uk/sites/default/files/reports/Efficient%20driving%20in%20electric%20and%20low%20emission%20vehicles.pdf

part which is interesting quote:
3. Watch your speed High speeds increase energy consumption in EVs more than they increase fuel consumption in conventional vehicles. Typically in a conventional vehicle, the most efficient speed (and therefore maximum MPG) is achieved at approximately 40 – 50 mph, but the most efficient speed for EVs is lower than this. The reason for the higher energy consumption at speed is that air resistance (drag) increases by the square of the vehicle speed. With conventional vehicles this effect is somewhat countered by the fact that vehicles are more efficient in higher gears, but with EVs the countering effect of gears does not come in to play. This is why electric cars are well suited to city driving where speeds are often lower.

So it would seem then that air resistance is not linear to speed

I posted the link to a mathematical analysis of the drag problem above, specific to drone flight.

 

[umanbean]

I think they are still around in the modded section that requires checking a box under your profile to be able view.

Thank you for that!

I did not know that, and wondered why I couldn't find the Mod sub-forum... just thought maybe they'd discontinued it (I'm trying to learn all I can about Super-Patcher and see if it's relatively safe and something I want to do, don't want to brick my new-to-me MPP).

Apologies for this OT post