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Old October 25th 07, 08:00 PM posted to rec.aviation.soaring
Bruce
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Posts: 174
Default Polar with spoilers extended?

This is the kind of rigid thinking that kills people.

While I entirely concur that being too slow on final approach is dangerous, one
has to understand the variables. If you teach that the needle has to be ON the
yellow triangle, what happens to the pilot when he suddenly notices the glider
he is in doesn't have one. While under pressure in a difficult situation.

For every weight and configuration there is a stall speed.
For every wind condition there is a different factor to add to stall to get to a
safe approach speed.

Personally I would far rather fly with someone who knows exactly why he/she is
trying to maintain a particular speed, than someone who is a master at nailing
some arbitrary speed. Which happens to be perfect for one set of conditions.

As a Std Cirrus driver (pre serial 75) I can vouch for the wisdom of being at
the right speed. Too fast by even a small margin and you will float forever, and
PIO if you try to fly it on. Too slow and the handling gets very interesting if
there is turbulence. That right speed varies widely depending on the wind and
other circumstances.

Maybe we make it too complicated - our rule is you have to be able to decide an
appropriate approach speed, explain why you chose it, and then keep within 5km/h
of it.

John Smith wrote:
Brian wrote:

Looking at a polar is exactly why it works. It is called Speed to fly.
It really only works well when you have some headwind. It does work
somewhat in calm conditions but is really not very effective. It
probably doesn't work at all in a tailwind condition.


First I thought that you were pulling our legs, but it seems you're
actually serious.

Every year a couple of pilots die because they are too slow on approach.
Where I fly, a student will fail his checkride big time if he's only one
knot below the yellow triangle on final. *Especially* with a headwind.
If you don't understand this, I *strongly* recommend you talk to a
knowledgeble instructor.