The use of rudder to maintain the runway centreline on take-off

A common misconception regarding this type of question is to assume that the wind is blowing the whole aircraft off the centreline, thereby needing a turn to correct this. However, in practice it doesn't quite work like this.

First of all, you need to understand how winds are described...

Winds come from the direction stated. So a northerly wind comes from the north. An easterly wind is from the east, and would be written 090. A wind of 130/15 is FROM the bearing 130 at strength 15 kts. (One way of remembering this is to think about the North wind. Its cold because it comes FROM the cold north.)

Let's assume you are making a take-off from Runway 18, with a westerly wind at 15 knots.

Caveat: You would also need to use a little aileron too for a crosswind take-off, but that wasn't the subject of these questions. Remember that other factors such as propellor torque and also propellor slipstream on the rudder also cause yaw.

Comment: Of course, in reality, pilots just make these (small) adjustments with rudder in all sorts of crosswind conditions (usually) without needing to think too much about it ;-)

References:

See http://www.recreationalflying.net/tutorials/groundschool/umodule11.html#toprocedure This comes from John Brandon's FlySafe Tutorials (which are extremely well written and worth a read/explore). Scroll down to the section titled 'Coping with significant crosswind'. This excellent link has been intermittent previously, but the material was recently moved to a new site, so it may be more reliable now (Sep 2010).

Atmospheric Picture

FL45, English Channel.