By the way, saying that lift is equal to weight is a bit wierd as the lift
is a force generated, while weight isn't a force, but a number calculated
from the mass and gravity. But I guess it's one of those simplification
making it easier for people to understand.

The above comment is wrong. First of all weight *is* a force. Then
"saying that lift is equal to weight is a bit wierd" is not wierd but
it is a simplification. This will be true only in straight and level
flight. In a turn or descent/climb, lift will not be equal to weight.

In fact in a steady climb lift is *smaller* than weight! This is
because weight is tilted backward relative to the flight path (weight
always point to the centre of Earth). Therefore it adds a component to
the drag, which must then be balanced by an increase in thrust (the
"excess thrust") but the weight component that must be balanced by the
lift is now less so lift is smaller.


Chris