Calculating hovering of an electro plane

[jsa0100]

I am trying to calculate the necessary amount of power (watts) for a RC plane to hover or to move vertically up. The electro engine has an efficiency of 80% and the propeller efficiency is 50%. The plane weight is around 1 kg.

 

[jsa0100]

I have calculatet that i need 9.8W and with 50% and 80% efficiency I get around 25W. In real life this types of planes needs around 200w.
So what am i missing?