Max Drift?

[Speedjeans]

Could someone who knows please explain the maths and equation behind max drift ie. is it always half the wind speed which is your max drinf or does it depend on miles per min that u are traveling?
Tar
SJ's

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Catch you on the flip side!

[CaptainSquelch]

Flying into the 70 kts headwind with a TAS of 60 kts you seem to have a drift of 180 degrees. As far as I know this is the max possible drift angle.

Sq

[Speedjeans]

Found the answer in a book
all sorted now thanks
So MD= TAS/miles per min.
eg. 240kts = 4 miles per min
therefore if you have a wind speed of 40 knots divide 40 by 4 = 10 degrees max drift
MD at 45 to 90deg is 10 degrees and so on and so on...
SJ's

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Catch you on the flip side!

[Prof2MDA]

This site has it all

http://www.best.com/~williams/avform.htm#Wind

[Skycop]

Remember that max drift only occurs with the wind at 90 degrees to your track. Use the clock code to assess how much of max drift applies.

Prof2MDA,

Comprehensive theory on that site but most pilots would be lost by the time they had used some of those formulae in flight!

A general point - wind forecasts are seldom very accurate. Not many (small /light) aircraft likely to require DR calculations have the facility to indicate current w/v, which tends to vary by the minute anyway. Highly accurate calculations aren't often required. Rules of thumb are most often all that is required, giving the pilot more time to look out and fly the aircraft.

[This message has been edited by Skycop (edited 08 January 2001).]