Propellerstyrka (kv)

[Jonatan]

What does kv mean?
K = Rpm
v = per volt.
This is short-hand for how fast the motor turns per volt. If the kv of a motor is 1,500 the motor will spin 1,500 times per minute per volt. If your battery pack is 10volts, then the motor will spin (without propeller) at 15,000rpm.
A general rule of thumb for outrunner motors;
500 ~ 1,300kv : 3D, slow fly planes incl. trainer.
1,400 ~ 2,500kv : Sport or Warbirds type planes.
2,600 ~ 4,000kv : Fast park-jet or EDF.

(from HobbyKing what is: kv)

[Jonatan]

Thrust

Trust = 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 = 3.14159
R = prop radius (in meters)
rho = air density = 1.22 kg/m^3

(från AeroQuad)

There are exactly 2 things which effect thrust.

1)prop diameter is by far the most important. Thrust varies as the 4th power of the diameter. If you double the diameter of the prop (and the rpm stays the same) you will have 16 times the thrust.

2)RPM. Thrust varies as the 3rd power of RPM. If you double the RPM (and the diameter stays the same) you will have 8 times the thrust.

(från Wattflyer)