"Jmarc99" wrote in message
...


As you said, I totally agree that "The gusts come from turbulence, and can
therefore come from *any* direction". So, the aircraft may also come
"close to stall without the extra velocity" with a tailwind situation
on the final leg!

But the rule says to add nothing in a tailwind situation? Probalbly
because
the decreasing windspeed when closer to the ground will effectively
produce
an increasing airspeed to the aircraft. But this doesn't looks right to
me,
to fly just 1.3 Vstall on the base leg and the final leg, just because I'm
going
to land tailwind!

Am I right to say that extra speed stands for a security reason. It is
not
simply to compensate the facing wind component. Otherwise, a pilot
may simply use less airbrake to get the same glidepath on the final leg!..

Thought, why not adding the extra knots to the 1.3 Vstall, whatever the
wind direction? Even tailwind?

Yes! Exactly the point I was trying to make in a long-winded fashion in
the paragraph below.

As to the tailwind question---the wing only knows airspeed. But the
landing field does not move with the wind, so the ground speed is
eventually important. The pilot will be tempted to slow at this point as
the ground speed seems high. Then there is the loss of control issue then
the glider is rolling on the ground, but has little aerodynamic control
due to low airspeed. Finally there is a wind shear issue at about 200 ft.
If you are landing downwind, you will descend into a decreasing tailwind,
and inertial forces will give you an increase in airspeed. It is best to
be on final approach before descending into this shear, which BTW, always
exists. It is just the magnitude that varies. This is so speed
adjustments can be made without the complications of turning--i.e. raised
stall speed, increased workload, etc.

So--here is the conclusion---for all situations

Sooner or later, you will have to slow down in order to land and stop. So
fly the "no wind" approach speed *and* add the gust differential, until
it is time to roundout and land. Use the brakes if the tailwind is
leading to a imminent loss of control.

Sure!

Happy Landings
Hartley Falbaum
ASW27B KF USA

Hartley Falbaum