You don't need a computer, LF. try a bit of this:
Max drift (ie the maximum amount you'd drift if all the wind was crosswind)can be calculated by dividing the wind speed by your airspeed in NMs per minute. Strictly speaking it should be TAS, but unless you're planning on going really fast or high the 'normal' 90,120 or whatever will work quite well.
So you're in a TB10 trolling along at 120kts. So that's 2 miles per minute. Wind off the chart is 20 knots, so max drift is 10 degs.
All you need to gauge now is how much of that max drift to take into account and this is where an imaginery clock face comes to hand.
If you think of the number of degs off your track that the wind is blowing (eg track 180, wind 195, wind angle=15) then the clock face represents the proportion of max drift to be applied.
So: 15 degs wind angle is 15 minutes on the clock. That's one quarter of the clock face, so one quarter of max drift.
20 degs, 20 minutes, one third of max drift.
30 degs, 30 minutes, one half and so on.
Once you get to 45 degrees of wind angle you just take the whole lot of max drift.
A quick eg then.
Track:180. Wind: 195/20. TAS/IAS:120.
So: max drift=20/2...10 degs.
Wind angle is 15 degs....quarter of the clock...quarter of max drift...2 & a half degs. Let's call it 3. So your hdg should be 183 (If it's anything like my driving then anywhere between 180 & 190 would be great
)
This method can also be used to work out your groundspeed, but using the wind speed instead of max drift. The only thing is you need to take the wind angle away from 90 to get the proportion of the clockface. It becomes obvious if you consider that wind all across doesn't affect groundspeed.
In the example above, wind angle is still 15 degs therefore 90-15=75. This is > 45 so you'd apply the whole lot of wind to your airspeed. ie 120-20....your G/S = 100kts.
One more eg and I'll shut up:
Track:330. Wind:020/30. TAS:90
---max drift:30/1.5=20 degs
So wind angle is 50 degs. That's > 45 so all the drift applies. Hdg:350.
90-50=40. 40=2/3rds of the clockface so 2/3rds of 30 kts is 20. 90 TAS-20: G/S=70.
Try it with a whizz wheel (CRP thingy), you'll be surprised how accurate it is.
Obviously with a tail wind you'd add the proportion of the wind.
There's no need to get your head in the cockpit. Just some simple maths and an imaginary clock...it works well. It's good for calculating crosswind components for T/O and landing as well.
Toodle pip,
Recover