On May 18, 5:11*pm, "noel.wade" wrote:
A couple of things:

1) Thanks John, that's the kind of comparison/number-checking I was
looking for. *I know that cloudbase/working-band/lift-strength play a
factor in determining whether the tradeoff is worth it; but didn't
think to do a straight MacCready comparison (the idea of pushing the
glider to high speed while still in spotty lift under a cloud-street
is just still feels awkward - discounting the few times where I've
approached cloudbase and needed to "bug out")!

2) I thought flying "energy lines" was the consensus these days, and
"Dolphin flying" was out - given that variometers lag and its
incredibly hard to time your pushes and pulls when flying through
alternating narrow cores and strong sink. *If your strong cores are
separated by a couple of miles, their miniscule contribution (say a 50
- 150 foot height gain) when you fly straight through them doesn't
seem worth it (especially when you start considering the risks of
hitting nasty sink before accelerating back up to cruise speed;
possibly wiping out all of your gains). *I've always been much more
tempted to slow down under weak spread-out lift (for example, under a
cloud thats about to OD).

Now just to turn this around and look at it from a different
perspective: *For the fast guys out there, when (if ever) *do* you
start slowing down a lot while flying straight ahead? *What're the
combination of factors that encourage you to switch into this mode?

Thanks,

--Noel

Reichmann used the term "dolphin flight" to mean flying streets or
energy lines.

I will give you a simple was way to think about how fast to fly in
lift on a street. As always there are many other factors in tactics
that may make you do some things differently but those usually have to
do with some change in the conditions ahead (end of the street, big
blue hole, final glide, etc).

Lets take a simple MacCready STF ring set of numbers. These should be
about right for your DG.

0 60
-1 65
-2 70
-3 75
-4 80
-5 85
-6 90
-7 95

Invert the numbers to average base cruise speed (this is how most of
us determine our average cruise speeds so we are not just pushing and
pulling all the time.

0 60
1 65
2 70
3 75
4 80
5 85
6 90
7 95

Now on the cloud street use your target thermal strength, the one your
willing to stop for be your guide. Again let's use 5 knots. Subtract
the difference between your target speed and the STF for the lift.
Example you're in 2 knot lift, 85-(85-75)=75.

Vario Speed
0 85
1 80
2 75
3 70
4 65
5 60 (thermal if really below cloudbase)
6 55 (thermal if really below cloudbase)
7 50 (thermal if really below cloudbase)