Flight mode Vs battery drain.

[DomDeV]

Hi all,

I can't find anywhere the statement that shows the different battery drain speeds of sport vs normal vs tripod - obviously went out for throttle. Basically arrange comparison between the three modes, maximum speed for that mode.

In one of my flights, looking at projected battery life time:
2m50s in sport mode, full throttle, 17.2 m/s
Then switching modes midflight;
5m40s in normal mode, full throttle, 12.0 m/s.

This suggests sport mode is around 75% as battery efficient as normal mode, but as battery capacity estimates are a bit wild at full throttle all it's hard to say....

Given all the factors, like motor efficiency, maximum tilt angle and battery efficiency higher power draw, it seems difficult to calculate.

Does anyone have a link to a reference - I guess I want to know how best to get maximum range, especially in critical battery conditions.

 

[BadWolf1]

It's not easy, and varies from drone to drone. Basically if you fly slowly a lot of the power is just keeping you in the air. If you fly fast it gets less efficient so there is some optimal speed which doesn't give maximum time but does give maximum range. The best attempt I've seen to work out the best range was here

long range drone DJI Phantom 3 professional

The DJI Phantom 3 Professional can be used for good long range flights. But how far it flies? This is calculated in this professional article.

www.technik-consulting.eu

 

[volition]

Hi all,

I can't find anywhere the statement that shows the different battery drain speeds of sport vs normal vs tripod - obviously went out for throttle. Basically arrange comparison between the three modes, maximum speed for that mode.

In one of my flights, looking at projected battery life time:
2m50s in sport mode, full throttle, 17.2 m/s
Then switching modes midflight;
5m40s in normal mode, full throttle, 12.0 m/s.

This suggests sport mode is around 75% as battery efficient as normal mode, but as battery capacity estimates are a bit wild at full throttle all it's hard to say....

Given all the factors, like motor efficiency, maximum tilt angle and battery efficiency higher power draw, it seems difficult to calculate.

Does anyone have a link to a reference - I guess I want to know how best to get maximum range, especially in critical battery conditions.

yes interesting topic. I’d be interested in distance by battery use too. Can you travel farther I sports mode or normal. Might just have to go to a huge open field and fly back and forth and see on the logs huh.

 

[Meta4]

yes interesting topic. I’d be interested in distance by battery use too. Can you travel farther I sports mode or normal. Might just have to go to a huge open field and fly back and forth and see on the logs huh.

Just like driving at 100 mph in your car, flying in Sport mode is not the most economical way to travel.
Here's an old post where someone did the testing with an old Phantom but the principles are the same:

Best fuel efficiency tests

I've created non-scientific practical test for battery efficiency. Made 4 laps, 2,5km each and three missions with different cruising speed (10,13,15m/s). Everything else was as identical as possible. Those are my first results. HealthyDrones.com - Innovative flight data analysis that matters -...

phantompilots.com

 

[boblui]

I have roughly tested the battery consumption in % battery capacity of my M2P under no-wind condition and full throttle :

P mode : 5.4% per km
Sport mode : 6.2% per km

 

[zeusfl]

The faster you fly, more wind resistance, more heat for your batteries, wear for the motors and electronics. Normal mode is the most efficient way to fly. I just use Sport as needed for weather factors or following a vehicle that require that extra speed.

 

[volition]

Just like driving at 100 mph in your car, flying in Sport mode is not the most economical way to travel.
Here's an old post where someone did the testing with an old Phantom but the principles are the same:

Best fuel efficiency tests

I've created non-scientific practical test for battery efficiency. Made 4 laps, 2,5km each and three missions with different cruising speed (10,13,15m/s). Everything else was as identical as possible. Those are my first results. HealthyDrones.com - Innovative flight data analysis that matters -...

phantompilots.com

I understand completely. So for example there is a baseline which below in speed is not efficient. Even more with a drone as a drone uses energy hovering, whereas a car doesn’t. I also understand over a certain speed you encounter drag, and other forces that will lose your efficiency.

now where that exact band is without the data no one can say with any certainty.

like you I do suspect that normal is more efficient then sport. But then again maybe 14m/s is more efficient (and I am talking specically about energy per km) and you cannot fly above 12m/s in normal.

as I said it is an interesting topic! And only the data on the MA2 will tell the full story.

 

[Meta4]

The faster you fly, more wind resistance, more heat for your batteries, wear for the motors and electronics. Normal mode is the most efficient way to fly. I just use Sport as needed for weather factors or following a vehicle that require that extra speed.

More than wind resistance, the faster you fly, the more your drone tilts and less thrust is available to hold the drone up.
That forces the motors to rev even harder to provide enough downward thrust to counteract the effect of gravity.
Flying hard in Sport mode burns battery much faster.

 

[zeusfl]

I understand completely. So for example there is a baseline which below in speed is not efficient. Even more with a drone as a drone uses energy hovering, whereas a car doesn’t. I also understand over a certain speed you encounter drag, and other forces that will lose your efficiency.

now where that exact band is without the data no one can say with any certainty.

like you I do suspect that normal is more efficient then sport. But then again maybe 14m/s is more efficient (and I am talking specically about energy per km) and you cannot fly above 12m/s in normal.

as I said it is an interesting topic! And only the data on the MA2 will tell the full story.

14m/s assuming perfect controlled weather conditions and this do not exist. Will be nice have a feature options in the firmware to set the max speed manually for each mode. This will allow to change the Normal mode from 12m/s to 14m/s.

 

[volition]

so guys tell me what speed is the most economical? That’s the interesting question I’d like to answer.

I’d also like to understand at under what speed does it start becoming not economical again.

from the logs I can calculate using differential calculations these numbers. But I think I might fly a few flights with this aim in mind as it will make the data more accurate.

yes on the whole sports mode is not the most efficient. Normal is, but is perhaps tripod mode even more efficient. I don’t think so. But I’d like a deeper understanding just for my own knowledge.

the Op and both myself have demonstrated we understand the theory perfectly. But to look into it deeper it does mean looking into the efficiencyat a whole range of speeds.

The article the Op linked is superb In its theory, but let’s see how it plays out in our logs on our AC’s.

let me have a play, I should be able to calculate pretty well using the logs. The fact battery percentage is only precise to round numbers and the log is at at 0.1s frequency will add some variance. But I think it will give a good picture.

 

[netsonic]

As a side note, if you sync your logs with Airdata you have a posibility to see how much current you draw on specific portions of your flight.

 

[RayOZ]

I’ve done testing with my MP about 2 years ago. Posted results somewhere, but not applicable for MA2. Look at the manual, and the quoted max flight time, would have speed next to it, which would be their most aerodynamic speed. M2P states 25kph with no wind.
But efficiency varies, max flight time per battery or max distance per battery? They are quite different
Even if you managed to calculate under ideal conditions, it won’t apply if it’s windy.
I think max time, 25kph, max distance 50kph.
With M2P RC, it displays RPM, so maintaining low RPM should give max flight time.

 

[volition]

I’ve done testing with my MP about 2 years ago. Posted results somewhere, but not applicable for MA2. Look at the manual, and the quoted max flight time, would have speed next to it, which would be their most aerodynamic speed. M2P states 25kph with no wind.
But efficiency varies, max flight time per battery or max distance per battery? They are quite different
Even if you managed to calculate under ideal conditions, it won’t apply if it’s windy.
I think max time, 25kph, max distance 50kph.
With M2P RC, it displays RPM, so maintaining low RPM should give max flight time.

yes that’s the big problem going to have to basically be ready for a super calm day to have any real accuracy. And also flying directions too. Which direction is most efficient. You would imagine forward, How much are the differences too. That is all the data the engineers have a hold of.

With the right plan I could generate some decent data. Exporting the csv from airdata flight player is probably the best go.

 

[Meta4]

Look at the manual, and the quoted max flight time, would have speed next to it, which would be their most aerodynamic speed.

The Air 2 manual specs only shows Max Flight Time = 34 mins (measured while flying at 18 kph in windless cond.
They don't show any data on the speed for Max distance like the M2 does.

With M2P RC, it displays RPM, so maintaining low RPM should give max flight time.

Lowest RPM is when hovering which is less flight time than when flying at 18 kph (max flight time).

 

[GadgetGuy]

I guess I want to know how best to get maximum range, especially in critical battery conditions.

Clearly, you don't want to use Sport mode when seeking maximum range, unless you encounter a headwind which exceeds your max N mode speed. In a critical battery condition, you want maximum range to be able to make it back, which will be in N mode, and likely maximum N mode throttle speed of 27mph. However, at critically low battery levels, output is throttled by DJI and you won't be able to reach 27mph, but still use full throttle anyway for maximum range. Seriously consider ditch landing the aircraft in a safe place, from which you can recover it, instead of risking a forced landing in an unsafe area, or a crash from very low battery levels, by continuing on, hoping to make it back.

 

[RayOZ]

Lowest RPM is when hovering which is less flight time than when flying at 18 kph (max flight time).

Actually I found flying forward does actually lower the RPM.
So perhaps 18kph is the optimum speed for max flight time.

 

[Meta4]

So perhaps 18kph is the optimum speed for max flight time.

Perhaps?
This is straight from the specs:
Max Flight Time = 34 mins (measured while flying at 18 kph in windless cond.

 

[GadgetGuy]

Still need to determine optimum speed for max distance per flight, since DJI did not provide this info in the owners' manual

 

[Mel 08]

When I first got mine I went to a field on a sunny windless day
Selected sport mode took off to 150f
Flew 700ft forward
1400ft reverse till battery was down to 25%
Did as close as I could the same with another battery in normal mode
Can't find my little black book at the moment but am pretty sure sport mode got to 25% 4 minutes before normal mode

 

[Dave Maine]

The math on this gets more complicated than what has already been identified. Higher speeds, whether in sport mode or p, means a greater tilt to the drone. This tilt reduces the vertical lift component of the propellor thrust. To avoid loosing altitude requires more power from the battery, in addition to the power required to increase speed horizontally against aerodynamic drag. Someplace in there is a tradeoff.