Is it most battery efficient to fly as fast as possible?

[gonuts]

If one wanted to fly as energy efficiently as possible, for as far as possible at what speed should one fly?

Is the max distance achieved at max speed?

 

[RayOZ]

You can do your own experiment with your Mavic 2 like I did with my MP.
Battery Efficiency Experiment

 

[Hedonist222]

Constant throttle at around 60/70% maximum performance.

The key is to reduce cycles of throttle on then throttle off.

 

[kilomikebravo]

60/70% maximum performance.

In pilot speak, that would be the max range airspeed. I bet DJI knows exactly what the number is and for sure the constant throttle is equally important. As as aside, the general rule of thumb is to fly faster in a headwind and slower in a tailwind.

 

[Hedonist222]

Hi kmb

What's max range airspeed?

 

[Mossiback]

My MP is most efficient with OA turned off. This lets me fly faster than P mode but slower than S (sport) mode. I don't know if it is the same for a M2 but worth an experiment.

 

[FormerMember07122019_2]

According to the Mavic 2 specifications you achieve the maximum flight time at constant 25kph (15.5 mph) with no wind. Conversely, you achieve the maximum distance at a constant 50kph (31mph) with no wind. I suspect each model is probably different due to aerodynamics, weight to power ratio, and other factors.

 

[brettbrandon]

Hi kmb

What's max range airspeed?

I believe it is the speed at which you get the maximum miles per tank of fuel. Or the best MPG...

 

[kilomikebravo]

What's max range airspeed?

Bret is correct or close enough for government work. In airplane speak it's the speed where miles/pounds of fuel is maximized. In Mavic speak it would be most miles/amp or whatever unit of measure you choose..

 

[Snowstorm]

There are two different max speeds. One is max endurance air speed, the max time you can stay in the air. Which is sound 25kmph for Mavic 2. The other is max range airspeed, which is much faster at close to 50kmph.

I am surprise that max endurance speed is not 0 hover, which implies that he Mavic generate some lift over its body?

 

[DanMan32]

I think the FAQ says it has to do with airflow, which I understood to relate to cooling, but aerodynamic lift could be what they meant.

 

[DanMan32]

Bret is correct or close enough for government work. In airplane speak it's the speed where miles/pounds of fuel is maximized. In Mavic speak it would be most miles/amp or whatever unit of measure you choose..

Measure of electrical energy is coulombs, but watt-hour is more commonly used.
When voltage is factored out, then amp-hour.

 

[gnirtS]

I am surprise that max endurance speed is not 0 hover, which implies that he Mavic generate some lift over its body?

The body has a slight curve to it. If you factor in the pitch angle the AoA is probably enough to produce some extra lift. Potentially the extra speed may mean *slightly* less power for the props to keep a desired RPM too.
Someone on here did a proper graph for the Mavic 1 and found the same results.

 

[¬Nomad]

The Pitch Angle and AoA is negative, whether flying forward backward or sideways
Body lift seems unlikely.

Rotary wing aircraft are always more efficient when moving than in the hover*, they benefit from translational lift when transitioning and are free of recirculation problems caused by remaining stationary within the area of its own heavy vortex, the horizontal componant of airflow through the tilted rotor disc unloads the rotor and height can be maintained with lower power

*Up to a certain speed

 

[Vitamin-J]

Looking at photographs of the M2 at hover, the propellers aren't pitched level, all 4 have slight angle of attack variations both forward & aft and side-to-side in steady flight. At these angles of attack, not 100% of the airflow coming off the propellers is being allocated lift. The propellers appear to have slight pitch, causing them to ever to slightly push against each other (makes sense for stability while at hover) - with most of the bias being on the aft propellers having the highest angle of attack in the forward direction (clearly for forward movement). I'm thinking this is what causes the reduced flight time of a hover, vs moving flight time.

I'm not seeing any remarkable features of the fuselage or struts that would provide considerable lift.

 

[lolo780]

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This should give an idea of max distance speed.
For endurance I've done a 33 minute flight at 7m/s constant speed. All stock battery.

 

[kilomikebravo]

For endurance I've done a 33 minute flight at 7m/s constant speed. All stock battery.

Lolo: You should send this off to DJI cuz you beat THEIR battery life estimate. <grinning> Who knows, as incredibly generous as the are, they might even send you a cool lanyard or something,

Impressive accomplishment though, no doubt about that. To me this seems to be a whole lot more valuable than max range and clearly your flight verifies DJI's battery endurance claim. (But I bet your fingahs were pretty darn tired after thirty-three minutes!)

 

[MaxHam]

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This should give an idea of max distance speed.
For endurance I've done a 33 minute flight at 7m/s constant speed. All stock battery.

I have no idea how the guy achieves that distance. When I am at (almost no wind) 6.4 km distance or roughly 4 miles my battery is at 55%. Turning around ist has upon landing 20% left.

The return trip I do through RTH assuming that DJI has made this the most efficient speed, which reads at 43 km/h. My trial was in the desert, battery temperatur around 50° C.
Maybe a lot is about temperature? The hotter the battery the less efficient it is?

 

[WithTheBirds]

I have no idea how the guy achieves that distance. When I am at (almost no wind) 6.4 km distance or roughly 4 miles my battery is at 55%. Turning around ist has upon landing 20% left.

The return trip I do through RTH assuming that DJI has made this the most efficient speed, which reads at 43 km/h. My trial was in the desert, battery temperatur around 50° C.
Maybe a lot is about temperature? The hotter the battery the less efficient it is?

At 50deg C cycle life is around half what you might expect at 20deg C. The battery will deliver good power though.

RTH speed isn’t the optimum speed for max distance for a given power consumption.

As has been mentioned earlier in this thread and elsewhere- the answers are in the DJI specs.

 

[lolo780]

From 20% you have a lot of range left. Fly by voltage after 0% and land it around 3.5v.

I have no idea how the guy achieves that distance. When I am at (almost no wind) 6.4 km distance or roughly 4 miles my battery is at 55%. Turning around ist has upon landing 20% left.

The return trip I do through RTH assuming that DJI has made this the most efficient speed, which reads at 43 km/h. My trial was in the desert, battery temperatur around 50° C.
Maybe a lot is about temperature? The hotter the battery the less efficient it is?