I need a crosswind calculator. They are available for the PALM as shareware but not for the PocketPC so I’m going to roll my own. Crosswind component data is usually found in a table or chart in printed format. The first task will be to design the equation. The mechanics of the software application form will follow easily.
CROSSWIND COMPONENT TABLE |
|||||||||
|
WINDSPEED |
ANGLE BETWEEN WIND DIRECTION AND RUNWAY HEADING |
||||||||
|
KNOTS |
10ø |
20ø |
30ø |
40ø |
50ø |
60ø |
70ø |
80ø |
90ø |
|
5 |
1 |
2 |
2 |
3 |
4 |
4 |
4 |
5 |
5 |
|
10 |
2 |
3 |
5 |
6 |
7 |
8 |
9 |
9 |
10 |
|
15 |
3 |
5 |
7 |
9 |
11 |
13 |
14 |
14 |
15 |
|
20 |
3 |
7 |
10 |
13 |
15 |
17 |
18 |
19 |
20 |
|
25 |
4 |
8 |
12 |
16 |
19 |
22 |
23 |
24 |
25 |
|
30 |
5 |
10 |
15 |
19 |
23 |
26 |
28 |
29 |
30 |
|
35 |
6 |
12 |
17 |
22 |
26 |
30 |
32 |
34 |
35 |
|
40 |
7 |
14 |
20 |
25 |
30 |
35 |
37 |
39 |
40 |
I google searched for a formula and found one that would duplicate these values.crosswind component = sin (angle between wind and runway) x wind speed.This, I found wouldn’t work out of the box. The sine function was looking for the angle in radians and not degrees. Go figure. To get radians you multiply the number of degrees by Pi and divide the result by 180. I’ll bet my kids knew this…
Example thus:
Runway Heading = 240 and Wind is 270 @ 20 knots
Theta = abs(270-240) = 30
Theta = (Pi * 30) / 180
X-Wind = 20 Sin(Theta) = 20 * 0.5 = 10 knots