On May 18, 6:25*pm, John Cochrane
wrote:
On May 18, 4:33*pm, "noel.wade" wrote:

All -

I've been flying with the assumption that flying slow in cloud-streets
is always a good idea. *

I disagree. It's always MacCready theory, if correctly interpreted.

Suppose the cloudstreet offers 2 knots up everywhere with occasional 8
knot cores. (Uvalde). Option 1: fly 50 knots without losing altitude.
You average 50 knots = 57 mph. Option 2: fly 85 knots, (I.e. cruise at
Mc 4 or so) , slowly losing, but stopping to thermal in the 8 knot
cores. You average 80 mph. (Typical uvalde winning speeds) The latter
is much faster. Reichmann offers the same advice.

John Cochrane

I would only add that the other important factor is the view ahead.
Sometimes slowing in moderate lift for a while- maybe to max l/d or
something as opposed to min sink, can keep you in contact with the
lift without having to circle. Modern gliders don't give up much
straight ahead climbing ability when flown a bit above l/d max.
Qualifier- if you slow down so much that you climb to where you can't
read the clouds effectively, you have made an important mistake.
You ask good questions.
UH