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Old 21st September 2010 | 23:25
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flyingpom
 
Joined: Mar 2009
Posts: 28
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From: Sydney
Speed Dist Time question

Ok, So here's a silly question that should be easy but it's got me stumped...

Using 120kts TAS as a base line:

1. If I travel 60 miles @ 120kts it will take me 30 mins

2. If have a 20kt headwind across the same distance:
  • I will be travelling at 100kts ( 16.67% slower)
  • I will travel 60 miles in 36 mins
  • Which is 6 mins longer i.e 20% longer
My confusion arises when i reverse the wind from headwind to tail wind

3. If I have a 20kts tailwind across the same distance:
  • I will be travelling at 140kts ( 16.67% faster )
  • I will travel 60 miles in 25.71 mins
  • Which is 4.3 mins shorter than @ 120kts
WHY for a 16.67% increase in speed I am NOT seeing the same equivilant decrease in time as with the 100kts example. i.e i was expecting ( outside the mathematics ) that if 16.67% slower made me 6 mins late then 16.67% faster will make me 6 mins early......

Am missing something logical here so feel free to point out my stupidity....
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