Anybody have a rule of thumb that helps break wind speed/dir into its crosswind
headwind components?

Bart

"Bart" > wrote in message
...
> Anybody have a rule of thumb that helps break wind speed/dir into its
crosswind
> headwind components?

Here are a few... the first two are most important, but put all four
together and it is all you need.

(1)
A 45 degree wind will have crosswind and headwind components of roughly 70
percent.

(2)
30 degrees (off the nose)- the crosswind is 50% and the headwind you can
round up to 90%.

(3)
For less than 30 degrees, the crosswind component versus the angle is close
to linear. In other words, for 15 degrees, 25% is close, 10 degrees, about
15-20%. Also, the headwind component is almost equal to the total wind in
this range, you might as well round it off. You can fudge the number by
subtracting 1 or 2 knots from your headwind if it makes you feel better :)


Here is an example:

Runway 14, wind 180 at 20 knots. The angle is 180-140=40 degrees. Pretty
close to 45... so use 75% and approximate the crosswind to 14 knots and the
headwind to 14 knots. Using a calculator I get 13 and 15- not bad!

Another example:

Runway 09, wind 070 at 15 knots. I get 20 degrees for the angle, that is
less than 30 degrees, in fact, it is 2/3 of 30, so instead of 50% I will use
2/3 of 50%. So, crosswind? 50% of 15 knots is 8, and 2/3 of that is 6.
Headwind? The angle is so narrow let's say 15 knots. The calculator says 5
knots crosswind and 14 knots headwind. If I had fudged the headwind down by
1 knot then I would have been right on.


And the last rule, which is really just the second and third ones over
again-

(4)
For greater 60 degrees and greater than 60 degrees, just switch the
crosswind and headwind rules with each other for the 30 and less than 30
rules.

(5)
Wait- a bonus rule, useful "on the fly" on cross country to get a crab
angle. 6 degrees equals 10 percent. So if you have a 10 knot crosswind and
you're going 100 knots, crab 6 degrees towards the crosswind. This will
give you a good starting point to correct your ground track from.


Hope this helps

Hey Thanks!

Bart

"Jim Carriere" > wrote in message ...
> "Bart" > wrote in message
> ...
> > Anybody have a rule of thumb that helps break wind speed/dir into its
> crosswind
> > headwind components?
>
> Here are a few... the first two are most important, but put all four
> together and it is all you need.
>
> (1)
> A 45 degree wind will have crosswind and headwind components of roughly 70
> percent.
>
> (2)
> 30 degrees (off the nose)- the crosswind is 50% and the headwind you can
> round up to 90%.
>
> (3)
> For less than 30 degrees, the crosswind component versus the angle is close
> to linear. In other words, for 15 degrees, 25% is close, 10 degrees, about
> 15-20%. Also, the headwind component is almost equal to the total wind in
> this range, you might as well round it off. You can fudge the number by
> subtracting 1 or 2 knots from your headwind if it makes you feel better :)
>
>
> Here is an example:
>
> Runway 14, wind 180 at 20 knots. The angle is 180-140=40 degrees. Pretty
> close to 45... so use 75% and approximate the crosswind to 14 knots and the
> headwind to 14 knots. Using a calculator I get 13 and 15- not bad!
>
> Another example:
>
> Runway 09, wind 070 at 15 knots. I get 20 degrees for the angle, that is
> less than 30 degrees, in fact, it is 2/3 of 30, so instead of 50% I will use
> 2/3 of 50%. So, crosswind? 50% of 15 knots is 8, and 2/3 of that is 6.
> Headwind? The angle is so narrow let's say 15 knots. The calculator says 5
> knots crosswind and 14 knots headwind. If I had fudged the headwind down by
> 1 knot then I would have been right on.
>
>
> And the last rule, which is really just the second and third ones over
> again-
>
> (4)
> For greater 60 degrees and greater than 60 degrees, just switch the
> crosswind and headwind rules with each other for the 30 and less than 30
> rules.
>
> (5)
> Wait- a bonus rule, useful "on the fly" on cross country to get a crab
> angle. 6 degrees equals 10 percent. So if you have a 10 knot crosswind and
> you're going 100 knots, crab 6 degrees towards the crosswind. This will
> give you a good starting point to correct your ground track from.
>
>
> Hope this helps
>
>

Yeh, Thanks !!


Bart wrote:
> Hey Thanks!
>
> Bart
>
> "Jim Carriere" > wrote in message ...
>
>>"Bart" > wrote in message
...
>>
>>>Anybody have a rule of thumb that helps break wind speed/dir into its
>>
>>crosswind
>>
>>>headwind components?
>>
>>Here are a few... the first two are most important, but put all four
>>together and it is all you need.
>>
>>(1)
>>A 45 degree wind will have crosswind and headwind components of roughly 70
>>percent.
>>
>>(2)
>>30 degrees (off the nose)- the crosswind is 50% and the headwind you can
>>round up to 90%.
>>
>>(3)
>>For less than 30 degrees, the crosswind component versus the angle is close
>>to linear. In other words, for 15 degrees, 25% is close, 10 degrees, about
>>15-20%. Also, the headwind component is almost equal to the total wind in
>>this range, you might as well round it off. You can fudge the number by
>>subtracting 1 or 2 knots from your headwind if it makes you feel better :)
>>
>>
>>Here is an example:
>>
>>Runway 14, wind 180 at 20 knots. The angle is 180-140=40 degrees. Pretty
>>close to 45... so use 75% and approximate the crosswind to 14 knots and the
>>headwind to 14 knots. Using a calculator I get 13 and 15- not bad!
>>
>>Another example:
>>
>>Runway 09, wind 070 at 15 knots. I get 20 degrees for the angle, that is
>>less than 30 degrees, in fact, it is 2/3 of 30, so instead of 50% I will use
>>2/3 of 50%. So, crosswind? 50% of 15 knots is 8, and 2/3 of that is 6.
>>Headwind? The angle is so narrow let's say 15 knots. The calculator says 5
>>knots crosswind and 14 knots headwind. If I had fudged the headwind down by
>>1 knot then I would have been right on.
>>
>>
>>And the last rule, which is really just the second and third ones over
>>again-
>>
>>(4)
>>For greater 60 degrees and greater than 60 degrees, just switch the
>>crosswind and headwind rules with each other for the 30 and less than 30
>>rules.
>>
>>(5)
>>Wait- a bonus rule, useful "on the fly" on cross country to get a crab
>>angle. 6 degrees equals 10 percent. So if you have a 10 knot crosswind and
>>you're going 100 knots, crab 6 degrees towards the crosswind. This will
>>give you a good starting point to correct your ground track from.
>>
>>
>>Hope this helps
>>
>>
>
>
>