Disable forward sensors for long range flights?

[saudio]

Question, if I have a long mission planned, and I don't expect any horizontal obstacles, and I have the RTH altitude set high enough to clear obstacles, would I be better off battery-wise to turn off the forward sensors?

1. Do the sensors themselves use any significant amount of battery power?
2. I understand the airspeed is higher with the forward sensors turned off. Would the higher airspeed (not on Sport mode, just the extra speed you get from disabling the sensors) help or hurt the overall range?

Thanks!

 

[Mavic_Ward]

I don't know about the battery drain of the sensors. I would expect not much.

I do find myself turning off the sensors if I'm flying towards the sun. There is some error at present that the sensors will stop the aircraft when the sun glare hits the sensors "just right." The aircraft things I'm about to hit something. I find this very annoying.

 

[dsd317]

1. Do the sensors themselves use any significant amount of battery power?

I'm not 100% sure, but I think it's using some amount of battery power. If every bit of power matters, then I would turn it off.

2. I understand the airspeed is higher with the forward sensors turned off. Would the higher airspeed (not on Sport mode, just the extra speed you get from disabling the sensors) help or hurt the overall range?

I think this depends on wind speed/direction. Running your motors harder to go faster will use up more battery.

 

[saudio]

I'm not 100% sure, but I think it's using some amount of battery power. If every bit of power matters, then I would turn it off.


I think this depends on wind speed/direction. Running your motors harder to go faster will use up more battery.

thanks. I'm just thinking there is an "optimal" speed for MPG (or miles per kilowatt) like there is for a car or boat. I know when you fly full speed in Sport mode your MPG goes down, and I assume if you flew at 3 MPH your MPG would go down, so I wonder where the sweet spot is.

 

[ScrappyMavic]

thanks. I'm just thinking there is an "optimal" speed for MPG (or miles per kilowatt) like there is for a car or boat. I know when you fly full speed in Sport mode your MPG goes down, and I assume if you flew at 3 MPH your MPG would go down, so I wonder where the sweet spot is.

Based on my testing by watching power consumption and velocity with CsvView, I've found 30 mph is very close to optimal J/m. (energy / meter) If you disable forward vision sensors and leave sport mode off, with full stick you will hit very close to 30 mph airspeed. This is definitely more efficient (lower) J/m than the 20 mph from vision sensors on or the 40 mph from sport. I still want to take more data to refine if it's really 28 or 32 etc. that's most efficient, but 30 is close, and it's much easier to just hold full stick on long flights.

 

[dacarter]

ScrappyMavic, great info. I was wondering the same thing.

 

[maikm]

1. Do the sensors themselves use any significant amount of battery power?

The "sensors" are merely stereo cameras. To make use of them, their images have to be processed, objects identified, and their distance and position in 3D calculated from the difference of the two camera images. All that takes a lot of computing power. DJI braggs about Mavic's CPU having 24 cores, and guess what they need those for. And since CPU is always a major power consumer in any electronics when under load, my conclusion is: if you absolutely need to maximize your range above all else, by all means turn obstacle avoidance off, both forward and downward.

2. I understand the airspeed is higher with the forward sensors turned off. Would the higher airspeed (not on Sport mode, just the extra speed you get from disabling the sensors) help or hurt the overall range?

This is already being discussed in this thread.

 

[CaveDrone]

thanks. I'm just thinking there is an "optimal" speed for MPG (or miles per kilowatt) like there is for a car or boat. I know when you fly full speed in Sport mode your MPG goes down, and I assume if you flew at 3 MPH your MPG would go down, so I wonder where the sweet spot is.

I see in the Mavic specs that the longest battery life is at 15.x mph with no wind


Sent from my SAMSUNG-SM-G870A using MavicPilots mobile app

 

[saudio]

Based on my testing by watching power consumption and velocity with CsvView, I've found 30 mph is very close to optimal J/m. (energy / meter) If you disable forward vision sensors and leave sport mode off, with full stick you will hit very close to 30 mph airspeed. This is definitely more efficient (lower) J/m than the 20 mph from vision sensors on or the 40 mph from sport. I still want to take more data to refine if it's really 28 or 32 etc. that's most efficient, but 30 is close, and it's much easier to just hold full stick on long flights.

Thanks to you and to all the discussion in this thread. This is exactly what I needed. This is a great place to get questions answered. Now if I could just get a few days of decent weather. I discovered that the house we used to live in is about 2.5 miles away by air (about 6 miles by road), and I want to go spy on them and see how they are messing up our dream home ;-)

 

[DV Mavic]

I usually get 21-24min of flight time on a battery. Tested for range last night. Left all sensors on, flew in sport mode and went out 5km no problem with full signal. Went out at 50km/h and came back at 60km/h. Landed with 12%. Really sucked the power as the whole trip was only 13mins. I'll be experimenting with some different combinations for efficiency but this thing is amazing. Defiantly a battery restriction on this thing not an rc problem because I only lost 1 bar of rc signal.

 

[EJay]

Interesting topic...
Sensors use computing power, so as discussed battery saving should be achieved by turning off sensors.

BUT as for range, I had an interesting chat with a real helicopter pilot on fuel consumption and I guess the same principles of physics would apply here.
It was a few months pre Mavic so unfortunately I didn't have reason to get too detailed.

The key principal was that was a sweet spot for FUEL BURN RATE and from memory that was somewhere half speed. ( I could be corrected here)
But for BEST RANGE (mpg) he said almost flat out (thinking around 90% throttle) gave the most distance. The longer TIME you are in the air, the more fuel you use fighting gravity.
This was for a fully optioned air ambulance of about 6.5 tonnes, but the physics would be similar and hopefully someone with the smarts in this area can add some precision.

Not sure where, but I read on a discussion place where someone did a "range test flight" and planned a Return To Home with a safe battery level, BUT to save battery slowed down the automatic return speed (wrong) and just squeaked home with about 10% battery instead of the planned +30% and wondered why!

Like the chopper pilot said, we get further going faster because we are less time up there fighting gravity.

Looking forward to hearing a bit more science on the topic.
I like the line of sight rule, so long range is academic for me without a team of spotters! In the meantime be aware of real life variable situations like a head wind.

 

[Phxbird57]

Interesting topic...
Sensors use computing power, so as discussed battery saving should be achieved by turning off sensors.

BUT as for range, I had an interesting chat with a real helicopter pilot on fuel consumption and I guess the same principles of physics would apply here.
It was a few months pre Mavic so unfortunately I didn't have reason to get too detailed.

The key principal was that was a sweet spot for FUEL BURN RATE and from memory that was somewhere half speed. ( I could be corrected here)
But for BEST RANGE (mpg) he said almost flat out (thinking around 90% throttle) gave the most distance. The longer TIME you are in the air, the more fuel you use fighting gravity.
This was for a fully optioned air ambulance of about 6.5 tonnes, but the physics would be similar and hopefully someone with the smarts in this area can add some precision.

Not sure where, but I read on a discussion place where someone did a "range test flight" and planned a Return To Home with a safe battery level, BUT to save battery slowed down the automatic return speed (wrong) and just squeaked home with about 10% battery instead of the planned +30% and wondered why!

Like the chopper pilot said, we get further going faster because we are less time up there fighting gravity.

Looking forward to hearing a bit more science on the topic.
I like the line of sight rule, so long range is academic for me without a team of spotters! In the meantime be aware of real life variable situations like a head wind.

coming from flying Phantom 2's and 3's. even if you go the fastest ( in ATT mode) you ended up using more of the battery. the best I found and this had been tested on the phantom forum. to leave the drone in GPS mod. the computer control the battery usage better. I'll get about 22 minutes of flight time in my Mavic full stick running 30 to 32 mph. One big thing I have found with the Mavic you don't need to be flying at 400 ft to get good distance. I've done 25000 ft at 81 from home point. At about 22000 the signal gets weak. I turn around at a little over 25000 ft I'll be at 54 or 56 % battery. make it back with 7 % left. The power I save on not having to go higher I feel helps me get out farther.

 

[EJay]

Wow Phxbird57 you have really gone the distance! You have confirmed that "full stick" (not sports mode?) gives good distance.
You are more experienced than me, but the key message is: Come home fairly fast if you are near the battery limit - DONT go slow to save battery!

Are you flying over flat farming country to get that good distance?

I wonder if Fixed Wing Mode would be slightly more efficient because the throttle is "set" rather than constantly being broadcast?

 

[Phxbird57]

Wow Phxbird57 you have really gone the distance! You have confirmed that "full stick" (not sports mode?) gives good distance.
You are more experienced than me, but the key message is: Come home fairly fast if you are near the battery limit - DONT go slow to save battery!

Are you flying over flat farming country to get that good distance?

I wonder if Fixed Wing Mode would be slightly more efficient because the throttle is "set" rather than constantly being broadcast?

 

[flyNfrank]

Question, if I have a long mission planned, and I don't expect any horizontal obstacles, and I have the RTH altitude set high enough to clear obstacles, would I be better off battery-wise to turn off the forward sensors?

1. Do the sensors themselves use any significant amount of battery power?
2. I understand the airspeed is higher with the forward sensors turned off. Would the higher airspeed (not on Sport mode, just the extra speed you get from disabling the sensors) help or hurt the overall range?

Thanks!

You went through your mental and visual check list and are ready to ignite the motor to prepare for launch. Before you drop the sticks to power the motors, one of the more important questions you should be thinking about is,....'what is the height of the tallest obstruction in the area I'm getting ready to fly in". If you are sure of what the obstruction is and it's height, add some safe footage to the amount and compare the number in your app's RTH Height and make changes if needed. Now-You're-Ready-For-TakeOff. (If you're unsure of obstructions in the area, I would suggest entering a number between 200-250ft)

If I'm going to fly a route or in a area I'm familiar with, I disable the sensors. The main reason I prefer to disable the sensors is, with sensors disabled it allows me to Yaw the AirCraft when RTH has been activated. I like being able to spin freely and zoom in and either record or take pic's while someone else is the pilot so to speak. Btw, when I worked for Dji I actually requested they add this same type of feature to the P3's. (Note- this feature is not possible if the sensors are enabled)

 

[EJay]

Good to see your mission.
Worked well with the antenna boosters. How much difference would there be without them?

 

[Phxbird57]

Good to see your mission.
Worked well with the antenna boosters. How much difference would there be without them?

I'm still debating if they did help. I know with the Phantom's it did help a lot. I had flown this route with the Mavic before with out the wind surfers. Now I was higher (158 ft). I'm thinking my sweet spot is around 100 ft for 26000 ft run.

 

[DV Mavic]

Ok, I just flew the exact same 5km run but only in p mode and full throttle. Much better.
Sport mode:
5km run
14 minutes flight time.
12% battery left
Sensors left on

P-mode:
Same 5km run
21 minutes
25% battery left
Sensors left on.
I was shocked to see 25% battery with 21mins of flight time. Impressive.

 

[geigy]

In the case of a head wind, sport mode may be more efficient. The extreme case would be where you are going backwards in normal mode, and forward in sport mode.

 

[newnan3]

Based on my testing by watching power consumption and velocity with CsvView, I've found 30 mph is very close to optimal J/m. (energy / meter) If you disable forward vision sensors and leave sport mode off, with full stick you will hit very close to 30 mph airspeed. This is definitely more efficient (lower) J/m than the 20 mph from vision sensors on or the 40 mph from sport. I still want to take more data to refine if it's really 28 or 32 etc. that's most efficient, but 30 is close, and it's much easier to just hold full stick on long flights.

So turning forward vision sensors off in P mode gets you going faster? Wonder why that is?