Doesn't it depend on what you are trying to optimize?
* if it's maximizing your arrival height at a point, then you do use a
different STF for upwind and downwind
* if it's minimizing the time for a final glide, then you use the same
STF, based only on your current rate of climb
* if you are approaching a turnpoint, it's not about classic McCready
STF, but about risk management: fly the MC STF and you might have to
take thermal while going upwind; fly more slowly so you can use a
thermal on the downwind side, but risk a lower course speed because you
are flying slower than the MC optimum.
Or putting it in "classic" terms, for the "rounding the turnpoint"
situation: Always fly the MC STF, but leave your thermal as soon as you
can glide around the turnpoint to your next thermal. A practical example
is a big dust devil or gaggle short of the turnpoint: go to the
gaggle/dust devil after rounding the turnpoint, not before.
Chris Rollings wrote, On 1/10/2014 11:35 PM:
If you are gliding from one thermal to another, optimum speed is the same
whether you are going into wind, downwind or no wind, it just depends on
the rate of climb achieved in the next thermal. If you are gliding to a
point on the ground, final glide or round a turn-point, then optimum speed
will be higher into wind than downwind.
At 19:10 10 January 2014, Kevin Christner wrote:
My understanding is that modern flight computers (which seem to have 10X
mo=
re features than anyone could possibly use) don't make adjustment to STF
ca=
lculations for the wind. From my reading of recent "authoritative"
sources=
(Brigliodori, Kawa) it is optimal to increase speed into the wind and
decr=
ease speed downwind, relative to non-adjusted McCready. Also of critical
i=
mportance to me would be a final glide optimizer. Currently when making
a
=
final glide I "move the dial" up and down in McCready speeds as I get
close=
to final glide. Often changing the McCready value up into the wind and
do=
wn with the wind leads to lower required altitude.
Am I missing anything?
2C
--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
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