View Full Version : thrust calculation

09-10-2012, 12:45 AM
hi , i am planning to make a flying robot and i need information about how much thrust is required to lift it and which motor should be used and its speed?
how to calculate these parameter?
advanced thanks.

09-10-2012, 06:28 PM
Hi Amaresh

It would have been great if you would have specified what type of "flying robot" you are going for e.g., quadcopter, single propeller, helicopter like design(with a tail rotor) etc.
In any case,

Static Thrust (e.g. hovering helicopter)

T = [ (eta*P)^2 * 2 * pi *R^2 * rho ]^0.3333

T = thrust (in Newtons)
eta = prop hover efficiency = 0.7-0.8 is typical for unstalled low-pitch props
P = shaft power = voltage * current * motor efficiency (in Watts)
pi = 3.1415
R = propeller radius (in meters)
rho = air density = 1.22 kg/m^3

Plugging in eta=1 will also give the absolute upper limit on the thrust obtainable for a given amount of power and a given prop radius.

Also, look into