This eighth in a series of articles is taken from here:
http://ozreport.com/forum/viewtopic.php?t=26379

Jim Rooney <<jim>> writes:

The VG is a very telling part. Yes, VG flattens out your wing. So
more of the glider stalls at the same time.

Here's the neatest part of VG in terms of landing. It's a huge tradeoff, so
there's a lot more to say about it, but, landing with full VG is the easiest
flare you will ever do.

The stall point of the tips is very close to the stall point of the root, so
while you're scooting along in ground effect, your flare window is absolutely
gigantic. When you flare, if the nose is going to stall, the tips are going to
stall as well. Your glider turns into a gigantic billboard and you can have your
shoes ripped off your feet from your legs getting flung forward so hard. When
that glider goes vertical, it stops with authority.

The tradeoff of course is firstly that you lose a lot of roll authority. I only
land full VG in silky smooth air in big fields. And even then, I just do it for
the fun of it. There is no practical purpose.

The second is that your trim speed will be higher, but your stall speed will
actually be lower. More of the wing will be flying as the nose reaches stalling
angle of attack, thus it will be producing more lift, it becomes in essence, at
lower speed, a larger wing.

So VG becomes a "flavor to taste" thing. It's whatever you "like". I tend to
prefer a 1/4 - 1/3 VG for landing. Most gliders retain most of their roll
authority in this range and you get a noticeable amount of the "flattening out"
benefit.

It makes flaring noticeably easier. So as long as it doesn't make the rest of
the approach a pain (I'm thinking about landings in choppy air here), then it
tends to be a good thing.