Ian wrote:
On 20 Dec, 14:42, "kirk.stant" wrote:

Ian, we appear to be comparing apples and oranges - you are talking
about not stalling on final, while I am talking about being able to
accurately thermal, and incidentally have a better instrument for
flying accurate approaches.

I wonder how much "flying at Clmax" matters in good thermalling
compared with "being in the right bit of the thermal"?

Minor correction: you should be thermaling at min.sink, which is the
point at which Cl^3/Cd^2 is maximized.

This is not in general the same as Cl max. Min.sink is usually at a
slightly lower AOA than CL max because Cd is rising steeply with
increasing AOA in the Cl max region. As a result, by the time you've
slowed to Cl max you've passed min.sink and your sinking speed has
started to increase.

Since the polar is usually flatter on the faster side of min.sink I
think you're better off thermaling somewhere between the min.sink and
best glide speeds, preferably nearer the former. Best glide is the speed
where Cl/Cd is a maximum.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
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