How much power to hover a 60kg drone?

[zenerbjt]

Dear Engineers,
For a battery powered drone of 60kg total , how much electrical power will be drawn from the battery to hover it?

There is an equation: P = K. m^(1.5)/r (from the following website)
https://justdrones.com.au/how-much-power-is-needed-to-hover/

Where:
P =power
K=22.35
m = mass in kg
r = propeller radius (length) in metres.

However, I am speaking of a drone with 4 motors and each motor drives dual stacked propellors which rotate in opposite directions. (so eight sets of propellers in 4 "pairs")

 

[wwfeldman]

the power required to lift the drone will be the same, regardless of the number of motors or propellers
you will need to develop a force equal to the weight of the drone to hold it steady,
more to make it rise at constant speed against gravity, and more to make it accelerate

your equation assumes one motor and one propeller
if you distribute it among multiple motors and/or propellers, the power required will not go down
it power required may rise because there will be additional losses associated with each motor and propeller

i see nothing incorrect about the derivation of the equation
however, i need some time for it to stew.

in any case, there are some things that probably matter that have not been accounted for:
turbulence will take away some of the energy and hence some of the force from the upward thrust

air fill in above the propeller may have a small effect - as the air is pushed down,
the air above the propeller will have a marginally reduced density, so air will flow in from beside and above.
the net effect is that the air density may not be the assumed value.

as the temperature rises, air density will drop

 

[BradtheRad]

The radio control helicopter field has been doing something like this. You could find out something from their experience. How to match weight to propeller, to electrical power. Of course 60 kg is halfway to normal size helicopter pilot.

 

[FvM]

Please notice that the quoted power calculation is based on a very simplified model of rotorcraft operation. Instead of determining the actual power at the rotor shaft, it's assuming 100 % rotor efficiency in accelerating a cylindrical air volume.

Within the validity of this model, the four rotors are lifting a quarter of the total mass each, two stacked rotors are counting as one. Respectively the question can be easily answered. More difficult to tell what's the actual power demand of real rotors.

 

[zenerbjt]

It appears, from the equation of the top post , that it takes some 21kW to hover a 60Kg drone with 0.5m propellor radius.
The coaxial, contra-rotating propellors just act like a single propellor, but about 10% more efficient.