Mavic Air - Flight Time

[tcope]

Was looking at the specs of the Air on DJI's site and noticed this:

Max Flight Time (no wind) 21 minutes (at a consistent 25 kph)
Max Hovering Time (no wind) 20 minutes


Not quite sure why hover time would be less then flying it at 25kpm. It will hover for 20 minutes but fly at 25kpm for 21 minutes.

 

[FoxhallGH]

Any rotary winged aircraft takes slightly less energy to keep it moving forward at a constant height, than it does to keep it in a position keeping hover. Not 100% sure of the physics, but if you Google it be prepared for a whole lot of equations with Greek letters and loads of graphs & aeronautic-speak. I think it's something like the prop's are always in 'clean' undisturbed air when the Drone is moving forward, but in the hover, you get a rotating column of air that puts downward pressure on the prop' disk (i.e. the air being forced down through the prop' disk, is accelerating the air above down onto the prop' disk and makes the drone work harder to keep its altitude. In addition, moving the rotating prop's forward through the air is 'adding' to the power provided by the motors, therefore they don't need to work so hard, and therefore, don't draw as much current.

 

[tcope]

Any rotary winged aircraft takes slightly less energy to keep it moving forward at a constant height, than it does to keep it in a position keeping hover.

Interesting. From what I found, part of it has to do with air passing through the blades being less at hover and more with movement. However, I'd still think this ignores the power to get to and maintain that movement. However, several of the other factors appear to be unique to helicopters, with a design to focus on these gains.

 

[dannybgoode]

Also in forward flight the prop disc does give some dynamic lift whereas in a hover the props spinning is all that is giving lift.

 

[FoxhallGH]

Some of the helicopter tech' applies - but it's a complex mix of factors ...
Do helicopters use more fuel when hovering?

 

[mjbok]

Was looking at the specs of the Air on DJI's site and noticed this:

Max Flight Time (no wind) 21 minutes (at a consistent 25 kph)
Max Hovering Time (no wind) 20 minutes


Not quite sure why hover time would be less then flying it at 25kpm. It will hover for 20 minutes but fly at 25kpm for 21 minutes.

Actual Flight Time Posted specs minus 25%