Why don't flight computers adjust STF for wind?

what flight computer are you running?

Most recently an Oudie, but for example with a 10kt headwind best L/D over ground would be better at MC 1 than MC 0.

On Tuesday, 14 January 2014 04:46:19 UTC+2, Eric Greenwell wrote:
Steve Leonard wrote, On 1/13/2014 8:17 AM:

On Monday, January 13, 2014 2:34:40 AM UTC-6, krasw wrote:

Yes, theoretically *if* thermals would drift perfectly with

wind...



Uh oh. Next problem. If thermals don't drift at the same speed as

the wind, how accurate is that wind speed your computer derrives from

drift while you are thermalling?



My experience with a 302 and SeeYou Mobile was the differences were

small compared to other variations due to time, location, and altitude,

and small enough that I usually didn't notice any difference. But, there

may be places that do have bigger differences, and I just didn't fly there.



--

Eric Greenwell - Washington State, USA (change ".netto" to ".us" to

email me)

I think many computers (or software) counts for wind variations due altitude. For flying in convective conditions this is just plain wrong and misleading. Wind doesn't change much (or at all) between altitude just over surface friction layer (few hundred meters) and cloudbase. This is because convection effectively mixes airmass momentum in convective layer. (Wave and mountains are of course different matter). Most important variations are due location and time.

On Thursday, January 16, 2014 3:04:17 AM UTC-5, krasw wrote:
I think many computers (or software) counts for wind variations due altitude.

You think? For example?

For flying in convective conditions this is just plain wrong and misleading.

Actually, it can and often does change significantly
(out in USA west for example). But, the more important
input to final glide is completely differing wind on
final glide from the point the glide is planned (think
final glides to Minden or Gawler, or any mountain site).

Hope that helps,
Best Regards, Dave "YO electric"

On Thursday, 16 January 2014 14:23:20 UTC+2, Dave Nadler wrote:
On Thursday, January 16, 2014 3:04:17 AM UTC-5, krasw wrote:

I think many computers (or software) counts for wind variations due altitude.



You think? For example?


SeeYou Mobile.




For flying in convective conditions this is just plain wrong and misleading.



Actually, it can and often does change significantly

(out in USA west for example). But, the more important

input to final glide is completely differing wind on

final glide from the point the glide is planned (think

final glides to Minden or Gawler, or any mountain site).



Hope that helps,

Best Regards, Dave "YO electric"

If you find sounding taken from a) flatland, b) during afternoon, c) with convective conditions, and d) wind changing direction and strength within convective layer, I would be more than interested in seeing it.

I have limited knowledge of Australian or western US geography, but I probably wouldn't classify Minden or areas east of Gawler flatland.

A few points from a south-western US perspective:

1) MacCready setting should be close to your achieved average climb. With 'ten-knot" thermals, we often find a climb average of 4 to 6 knots - you have to find them and center them as well as climb!

2) Wind speed and direction often does change with altitude, but this is not a major factor until final glide.

3) The best practice to approach an upwind turnpoint is with the minimum altitude for safety. You don't need to change MacCready setting, but don't carry excess height flying against the wind.

4) If in doubt, I use a MacCready setting of 3 - I have never found zero or 1 to be useful as it has no margin for safety. (I don't think I could live anywhere where a MacCready setting of 1 is the norm!)

Mike

Mike the Strike wrote, On 1/17/2014 7:12 AM:
4) If in doubt, I use a MacCready setting of 3 - I have never found
zero or 1 to be useful as it has no margin for safety. (I don't think
I could live anywhere where a MacCready setting of 1 is the norm!)

Many of us use two MC settings: for me, the STF vario is set to 1 or 2
(3 on amazing days); the flight computer MC setting is usually set to 4
(5 or 6 as the area between airports gets scarier).

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)