Most efficient speed for max range

[pogopilot]

Under ideal conditions (no wind, LOS flight) what is ideal flight speed to maximize range/battery life?

 

[Pushpak]

Under ideal conditions (no wind, LOS flight) what is ideal flight speed to maximize range/battery life?

According to user manual, Max flight time 27 mins (0 wind) at a consistent 15.5 mph (25 kph). So technically that should give you 7 miles/11.25 kms.

It also says, max flight distance (0 wind) 8 miles/13 kms. Not quite sure under what speed they meant.

 

[CyberNate]

The max distance will be covered at the optimal RPM speed of the motors. With no wind, that speed is at around 30mph. You can see the max efficiency RPM/Power in the tachometer by going to sport mode. The RPM/Power line goes around the Radar circle. The point where the green line turns blue is the maximum efficiency point. Keep the speed near that intersection and you'll see a speed of about 30mph when there's no wind. I've gone 44,000 feet without much effort, and that was not even an optimal day. Had a fair amount of cross wind.

Edit: I should add, you can achieve the optimal speed in an easier way as well. Simply turn off the front obstacle avoidance and use P mode. Push the right stick full forward. The Mavic is programmed to go right at about 30 mph, which I believe is no accident. That is for maximum efficiency.

 

[saudio]

The max distance will be covered at the optimal RPM speed of the motors. With no wind, that speed is at around 30mph. You can see the max efficiency RPM/Power in the tachometer by going to sport mode. The RPM/Power line goes around the Radar circle. The point where the green line turns blue is the maximum efficiency point. Keep the speed near that intersection and you'll see a speed of about 30mph when there's no wind. I've gone 44,000 feet without much effort, and that was not even an optimal day. Had a fair amount of cross wind.

That's what I've read, but you have to either be in Sport mode or turn off the front sensors to hit that speed. I prefer to turn off the sensors because then wide open is almost exactly 30 MPH.

 

[stratos]

Well this is a good question. I would have tough that P mode consumes less battery than S mode.
Now, of course S mode burns battery faster, however, you are travelling at almost double the distance as of P mode, considering that when you gain enough momentum if you start cruising without change or direction or height S mode might be more efficient.

Now in P mode its clear you consume less battery but also your craft moves slower and you get less momentum.

 

[CyberNate]

Well this is a good question. I would have tough that P mode consumes less battery than S mode.
Now, of course S mode burns battery faster, however, you are travelling at almost double the distance as of P mode, considering that when you gain enough momentum if you start cruising without change or direction or height S mode might be more efficient.

Now in P mode its clear you consume less battery but also your craft moves slower and you get less momentum.

Mode doesn't matter. Running the motors at the optimal RPM is what matters. Electric motors are most efficient somewhere around 60% of their max RPM. DJI has already programmed that point into the tach and P-mode when obstacle avoidance is off.

 

[stratos]

Mode doesn't matter. Running the motors at the optimal RPM is what matters. Electric motors are most efficient somewhere around 60% of their max RPM. DJI has already programmed that point into the tach and P-mode when obstacle avoidance is off.

I agree buddy.
Have you running the number on which mode is mode energy efficient?

 

[pogopilot]

The max distance will be covered at the optimal RPM speed of the motors. With no wind, that speed is at around 30mph. You can see the max efficiency RPM/Power in the tachometer by going to sport mode. The RPM/Power line goes around the Radar circle. The point where the green line turns blue is the maximum efficiency point. Keep the speed near that intersection and you'll see a speed of about 30mph when there's no wind. I've gone 44,000 feet without much effort, and that was not even an optimal day. Had a fair amount of cross wind.

Edit: I should add, you can achieve the optimal speed in an easier way as well. Simply turn off the front obstacle avoidance and use P mode. Push the right stick full forward. The Mavic is programmed to go right at about 30 mph, which I believe is no accident. That is for maximum efficiency.

Great answer, thanks! Now about your 44,000 feet, I assume that is an out 'n back, correct?

 

[CyberNate]

Great answer, thanks! Now about your 44,000 feet, I assume that is an out 'n back, correct?

No, just flying around. I have too much interference around me for distance flights. The only time I did a distance run was over the bay, but it was really windy and didn't want to push it. I did 3.5 miles out and back and had 30% battery remaining.

 

[wildpig]

According to user manual, Max flight time 27 mins (0 wind) at a consistent 15.5 mph (25 kph). So technically that should give you 7 miles/11.25 kms.

It also says, max flight distance (0 wind) 8 miles/13 kms. Not quite sure under what speed they meant.

The max distance will be covered at the optimal RPM speed of the motors. With no wind, that speed is at around 30mph. You can see the max efficiency RPM/Power in the tachometer by going to sport mode. The RPM/Power line goes around the Radar circle. The point where the green line turns blue is the maximum efficiency point. Keep the speed near that intersection and you'll see a speed of about 30mph when there's no wind. I've gone 44,000 feet without much effort, and that was not even an optimal day. Had a fair amount of cross wind.

So max flight time is 27 min but probably shorter distance due to slower speed as compared to max distance which would be covered maybe faster with faster speed but lower total flight time? Nate, what's the flight time at 30mph?

 

[CyberNate]

So max flight time is 27 min but probably shorter distance due to slower speed as compared to max distance which would be covered maybe faster with faster speed but lower total flight time? Nate, what's the flight time at 30mph?

Around 22 minutes pushing it, 20 minutes fairly easily. A better way than sport mode is to use P -mode and turn off obstacle avoidance. Full right stock is right at optimal speed. You need a day with very little wind. Wind really uses up battery, especially cross wind.

 

[wildpig]

44k ft is quite a distance. so far my best is 26000ft on a direct round trip with like 1 minute loitering. got around 19% left. but it did have about 4mph headwind coming back. So it got the 4 mph tailwind going forward. But in P mode with obstacle avoidance, the speed is hard limited to 20mph so i guess it might have saved a little battery by being able to throttled down a little on the way out?

 

[CyberNate]

Made it out 22604ft (4.28 miles) and that was with a strong head wind flying low at 164 ft altitude in the city. I turned around at 42% battery to come back which gives you an idea of the amount of wind I flew into and still at 7% when landing. Completely stock.

 

[wildpig]

I am in the middle of a city, not with a lot of high rises though. Maybe you were getting better range and had better elevation of the controller and less signal interference where you are? I still had like 3 bars when i got to 13k ft, but then it started screaming lotsa interference.... The 1 min loitering was actually it just hovering because i couldn't get it to follow any command. It and i just gave up and the auto return cut in in good time b/c i was not able to get it to follow any command.

 

[CyberNate]

I am in the middle of a city, not with a lot of high rises though. Maybe you were getting better range and had better elevation of the controller and less signal interference where you are? I still had like 3 bars when i got to 13k ft, but then it started screaming lotsa interference.... The 1 min loitering was actually it just hovering because i couldn't get it to follow any command. It and i just gave up and the auto return cut in in good time b/c i was not able to get it to follow any command.

You need clear line of sight between the drone and controller. Even objects that are close to the line of sight will cut down the signal significantly. You also need to point the controller in the direction of the drone and have the antenna straight up and parallel in a way that if you draw a perpendicular line through the antennae they will line up with the drone. I have a slight elevation from where I fly from, perhaps 50 to 100 feet above the terrain I'm flying over.

 

[wildpig]

Yep 30 mph does give you the longer range than 20 mph, although the battery life is shortened by about 2 mins for me..

My question is it seems like dji locks your speed at 20 or 30 mph so what happen is that you seems not to be able to take advantage of any tail wind but then you get all the bad disadvantage of slower speed with head wind. Am i right?

 

[CyberNate]

Yep 30 mph does give you the longer range than 20 mph, although the battery life is shortened by about 2 mins for me..

My question is it seems like dji locks your speed at 20 or 30 mph so what happen is that you seems not to be able to take advantage of any tail wind but then you get all the bad disadvantage of slower speed with head wind. Am i right?

Somewhat true, although you will use much less power with a tail wind. I went 4.28 miles return leg with only 31% battery consumption. I was using p mode with obstacle avoidance disabled.

 

[wildpig]

Somewhat true, although you will use much less power with a tail wind. I went 4.28 miles return leg with only 31% battery consumption. I was using p mode with obstacle avoidance disabled.

So you agree that DJI set a hard limit on the speed? being someone with flying experience, it kinda screw with my head a little planning a flight that i can't take advantage of any tailwind for faster GS but then get all of the slower GS for a headwind.....

 

[CyberNate]

So you agree that DJI set a hard limit on the speed? being someone with flying experience, it kinda screw with my head a little planning a flight that i can't take advantage of any tailwind for faster GS but then get all of the slower GS for a headwind.....

There is a limit of around 42 mph in sport mode. So if you have a 12 mile per hour tail wind, you could use sport mode and adjust tachometer until speed is at green/blue intersection. This would give you 40-42 mph ground speed yet running motors at efficient speed.

 

[wildpig]

There is a limit of around 42 mph in sport mode. So if you have a 12 mile per hour tail wind, you could use sport mode and adjust tachometer until speed is at green/blue intersection. This would give you 40-42 mph ground speed yet running motors at efficient speed.

What i am asking is that it seems like dji is limiting the speed to ground speed rather than limiting the speed by limiting the RPM (pseudo airspeed). at least what I have seen so far in P mode , with or without forward avoidance, the forward speed indicated on the controller seems to be locked at 20 mph with forward avoid and locked at 30 mph without. I am saying this b/c when i fly with a tailwind, my speed on the controller never exceed either 20 or 30 mph. and when i make the reverse trip now with headwind, my speed on the controller now showing a slower speed than either 20 or 30 mph.

I think that dji should really peck the limit to rpm rather than ground speed. It's a real handicap when they do this limit regard to ground speed rather than rpm. This is especially true with wind around, b/c now you are also losing out on the wind assistance on your leg with the tailwind while you get the penalty of the headwind going the other way