Air Navigation - Day 1
Sorry to bang on about this, matt, but think you may be confusing two completely different things:
WEATHERCOCKING
The tendency of an aircraft with conventional vertical tail surfaces to swing its nose into a stiff wind when it is resting on the ground (i.e., NOT airborne).
DRIFT IN FLIGHT
[Assuming no side-slip, i.e., with the aircraft flying straight IN RELATION TO THE AIR MASS.]
As you say, the difference between the HEADING (the bearing in which the aircraft is pointing) and the TRACK (the bearing of the track made good over the ground).
This results from the movement of the AIR MASS (at the altitude of the aircraft) in relation to the ground. The air mass is, after all, what is supporting the aircraft.
If the true airspeed (TAS) of the aircraft is 120kts, and there is a 90-degree crosswind of 40kts, the drift will be approximately 20 degrees.
The relationship between HDG/TAS, W/V, and TRK/GS can be mathematically represented by a triangle of velocities, which is what we old farts used to do on a Dalton Computer.
Last edited by Chris Scott; 19th Feb 2008 at 17:35.
Reason: Typo