'Scuse em fer butting in, but unless HEADING (not track) and WIND are at 90 degrees there will always be a head/tail component.
If you are not convinced, apply a 'crosswind' of, say, 100kts and see how fast you go along track
I must confess to writing this without having thought about it in detail, but I think the case of a crosswind having a
zero effect on one's speed along the desired track is when the wind is perpendicular to the
vector sum of one's heading and the wind (or maybe the vector sum of one's track and the wind).
That's why using the circular slide rule (the wind calc side of it) in a particular way requires iteration, and the number of iterative steps increases as the wind becomes a higher % of one's speed.