In article ,
Martin Gregorie wrote:

On Tue, 04 Nov 2003 01:04:03 +1300, Bruce Hoult
wrote:

In article ,
(JJ Sinclair) wrote:

Lets see now, I'm about here, so how far to home? Should have put
some of those "old-fashioned" distance circles on this
"old-fashioned" map. OK, at 1000 feet per 15 statute miles

What are you flying that has a 80+:1 glide angle? Surely you can't
count on making up that much in arbitrary air just by dolphining, even
in a 60:1 supership?

100 ft per km is really easy, so that's what I generally use. That's
33:1.

Looks like a good, conservative figure to me. It was suggested that I
used 100ft per 6 miles as baseline when I first started taking the
club Pegasus cross country. The Peg. is fitted with an old Cambridge
Mk 4 vario and doesn't have a glide computer. 1000/6 miles is pretty
close to 100 ft/km. Now I fly with my own (removable) GPS, configured
to use metric units, so 1000ft / 10 km is a no-brainer to estimate.

It's conservative in the Janus (or even Twin Astir), which is good
because I don't really want to have to derig and rig them.

It's not so conservative in the PW5! But it's more like reality
(especially if you can eke out a little bit better than still air).
There have been several times when I've made final glides from cloudbase
in the last proper thermal of the day ten or fifteen km before the last
turn point (say 40 - 50 km total) and made it right on the numbers, or
even gained a few hundred feet. And if I don't make it its no problem
because the PeeWee is easy to put down anywhere, and the wings aren't
too heavy for my GF to lift.

Hmm ... come to think of it, although I've landed out just short of the
airfield, I think so far that's only been on flights when I knew from
the outset that I didn't have enough, and there just plain wasn't any
more to be had!

-- Bruce