I've been contemplating this question: at what air speed can the I2 cover the most distance on a set of full batteries. For this theoretical question, we can assume no wind, level, straight flight.

This could translate to a more practical question: if I'm running low on battery, what's the optimal speed to fly home at?

Since it would require many test flight in an almost impossible to control environment, maybe the engineering staff at DJI can chime in?

I think this web article answers the question quite well ... quietest flight is most efficient ... you can "listen" as you do flypasts at various speeds ...

http://quadcopter101.blogspot.al ... ficiency-hover.html

I believe the "quietest flight" which requires no collective (upward left stick) compensation is achieved at about 10 mph, and this also leads to very smooth videos.  I try to keep my drone flying at this slow speed all the time and I don't let it "hover" or climb to unnecessary altitude since this shortens the flight duration significantly.  I transition from takeoff into forward flight before the undercarriage is fully raised, and I minimise the "hover" portion of landing by doing 45 degree slow descents.  I'm getting 30 minute flight times when there is no wind ...

As the speed increases beyond 10 mph, the flight becomes more noisy, and small amounts of upward left stick might be required to maintain the same altitude.  The flight is less efficient the faster you go beyond 10 mph.

Best,
Rob

RobAlbania Posted at 2018-5-20 15:38
I think this web article answers the question quite well ... quietest flight is most efficient ... you can "listen" as you do flypasts at various speeds ...

http://quadcopter101.blogspot.al/2014/02/flight-school-5-power-efficiency-hover.html

Thanks for the link, Rob!

It's an interesting read. However, I don't think it is exactly what I'm looking for.

What I wanted to know is the optimal speed to cover the most distance, not necessarily the lowest power consumption. Case in point: I flew a test flight in the desert yesterday with a total distance of 7.86 miles. Flight time was 15:23. Landed with 13% battery left. The flight was a mixture of P and S mode, under very strong wind conditions (red wind warning popped up many times).
In the flight scenario you described, flying at a constant 10mph gives you 30 minutes of flight time. The total distance, however, would have been only 5 miles.

For the most part, it's an interesting question to ponder. It also has some practical use scenarios like RTH with low battery.

Thanks!
Alex

Hi Alex,

Well your original question included the statement "For this theoretical question, we can assume no wind, level, straight flight."
You are now modifying the parameters of your original question to include "under very strong wind conditions".

You have no option in very strong wind conditions except to fly into the wind for your outward "optimal distance route", you will have to offset the wind speed plus add 10 mph (which is inefficient), monitor battery usage until 50% capacity, then return knowing that you will definitely make it back with the added benefit of the wind speed / power added to the 10 mph of the drone.

Suggest you get an Anemometer so you can measure the wind speed.  Anything over 30 mph is difficult.

Thanks,
Rob

Hi Rob,

I was merely using data from an actual flight (with strong winds) as a counter point. If I could cover 7.86 miles in very strong winds at speeds between 25-40 mph, surely I could do better (i.e., longer distance) with those kinds of speeds if there were no wind? At the very least I don't think I'd do worse if no wind.

But yes, I agree that having wind would make the problem even more complex. So let's disregard that. The original question still stands though, what is the optimal speed to fly at in order to cover the most distance (assuming straight level flight, etc)?

Alex

I'm sure DJI engineers chose the most optimum air speed for distance as the air speed for smart RTH.

You can simply press RTH button and see at what air speed your Inspire 2 is returning to home point. For the Inspire 1, the smart RTH air speed is 10m/s, i.e. 36kph (22mph).

Henry

Henry M.Y. Posted at 2018-5-21 13:57
I'm sure DJI engineers chose the most optimum air speed for distance as the air speed for smart RTH.

You can simply press RTH button and see at what air speed your Inspire 2 is returning to home point. For the Inspire 1, the smart RTH air speed is 10m/s, i.e. 36kph (22mph).

That is brilliant!

Will test it out.