I think that if the airspeed is reduced by 40 knots or so in, say, 20
seconds, that's a zoom. I often see a quicker speed reduction than that. I
would agree than smooth control inputs are better. Timing of the airspeed
changes is more important than the amount.

The key as to whether it worked or not is the barogram trace. If the
downward trend of the glide is displaced upward at the zoom so a new trend
starts at the top of the zoom, there was a net gain. If the thermal was too
narrow or was followed by heavy sink, the barogram trace will just show a
spike with no change in the trend - just a loss in average speed due to the
slowing.

A couple of pilots who seem to be the masters of the "Long Glide" are Kevin
Wyatt and Gary Ittner. You will notice that their airspeed trace is almost
an exact inverse of the vario trace. i.e. vario up, arispeed down and vario
down airspeed up.

On the other hand you will see pilots where there is only a weak correlation
between airspeed and vario. These folks seldom get more than the published
L/D.

Bill Daniels


wrote in message
oups.com...
Bill, are you seeing the effect of "dolphin" flying, or just following
the lines of energy (or, avoiding sink). I try real hard to avoid the
classic "pull hard in lif" type of dolphin flying, since in my
experience it slows me down (from comparison flying); OTOH, I try real
hard to look for and exploit lift lines, and gently vary speeds to
match the trend of the airmass. Doing this, I consistently better my
polar's L/D for the speed being flown.

Of course, this is semantics - whatever technique being used, it is a
skill that takes knowledge, practice, and good instruments.

And the fast pilots usually have all three!

Kirk
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