As I read this, I think about how that one hour of
less
flying means different things. Less exhaustion, for
one.

The most impressive thing to me about the 1-26 diamond
guys isn't the flight itself, but the amount of time
spent doing it. The super-long wave flights (Kestrel?)
were similarly impressive just from the endurance perspective
alone.

I personally have seen forecast conditions and experienced
times when a 300km flight looked possible, but the
gliders I had available had low enough performance
that I personally didn't have the recent experience
with endurance flights to make the 300km with what
I considered an adequate margin of safety.
For me, the difference between a 3 hour and a 6 hour
flight is
still quite significant. A flight of over 10 hours
(which one might need for a 1000km) looks quite daunting
to me. IIRC some of the Kestrel wave flights exceeded
this.

For the guys who are recommending max wing loading,
how much of this is because you want to make the flight
as
short as possible for endurance reasons?

In a similar vein, a 500km downwind seems a lot different

(in endurance terms) than a triangle or O&R.

At 02:36 03 August 2005, Andy Blackburn wrote:
At 18:48 02 August 2005, Eric Greenwell wrote:
Tactically, one should take off with full ballast early
enough to have a
chance of completing the flight, and drop whatever
it takes to stay up.

That's one approach - but keep in mind that the difference
in climb rate between full and empty (in a 45-degree
bank) is less than 50 fpm.

Furthermore, the McCready-derived XC speed differential
for full versus empty water is 6-9 knots. The actual
difference with streeting, etc. may be greater. That
amounts to about an hour less time on course with water
versus without. To break even without ballast you'd
have to make about 80 miles before you could get started
on course with ballast.

I'm thinking this would only be true if the day developed
with either very weak (0.5-1.5 knots climb, dry) or
very narrow thermals for a very long time (1-2 hours).
Under those conditions I don't think you're making
80 miles even if you have Helium in your wings.

I'd recommend taking tows until you can stay up with
full water.

9B




Mark J. Boyd