Turning in circles
Twisting, turning,
bucking, banking, spinning, and spiralling up to the sky ..
everyone seems to have their own style, a characteristic way of
moving through the air. I am also learning how to fly in the SA
sky, and by the reconning of a bird, with 1000hours airtime, I am
about a one-year-old eagle (sometimes turkey), barely out of my
puberty-feathers. But I often get to cloudbase, so maybe my
advice on tweaking the most out of your turns, to save altitude
and stay in the lift will help you.
3.1 Crossovers
Most harnesses have some form of
cross-bracing built into them, either as integral angled straps
that run from the chest-strap, or as add-on adjustable
cross-webbing. The purpose of the cross-over is to re-distribute
the pilot's weight during large collapses of the wing. Instead of
falling towards the collapsed side of the wing, the pilot is
suspended by the cross-brace which transfers the weight to the
wing which is still flying.
All well and good, except that many pilots fly with cross-overs that are too tight (they should bow loosely during normal level flight). A cross-over should only begin to take effect when your seatboard has tilted past 45degrees. If it is carrying your weight before this point, then your weight-shift turns will have no effect, making your flying less efficient. Your glider will also tend to suffer more asymmetric collapses, as the rigid position of the harness does not tilt to absorb the roll movements of the wing.
3.2 Chest-strap settings
Apart from keeping you in the harness, the
chest-strap determines the distance between your carabiners. A
wide chest-strap (>38cm carabiner to carabiner) will result in
a more sensitive harness, easier to weight-shift, with superior
ability to read the feedback from your wing. At some point it
does become too sensitive, and it is unnerving having a
chest-strap that flaps in the breeze. 38cm seems to be a good
compromise. A tight chest strap (<38cm) reduces sensitivity,
and because the carabiners are now inside your body-line, the
harness has a greater tendency to spin (yaw). This becomes
problematic during (uncommon) violent collapses and negative
spins, as the pilot can experience twists in the lines due to
harness rotation.
3.3 Brakes, speed to fly and flying fast
Your glider's sink rate is minimised with
around 1/4brakes applied (one good kink all along the trailing
edge of the glider). So if you're trying to get as high as
possible, as fast as possible, theory suggests you should have
1/4 brakes on in the thermal. So how do you turn? By shifting
your weight. How much? Lots. If that isn't enough to keep your
circle within the thermal, then you need to employ the negative
turn, not pull more brake than 1/4 on the inside wing.
3.4 Negative turn
The negative turn offers a very tight
circle when executed properly. The first stage is mentioned above
- the bow-back. Some wings bend slightly, in others you can just
feel the tension in the wing, waiting to be released. So first -
1/4 brake both sides. Second - weightshift to the side of the
turn you want. Then third - release the outside brake. This
allows the wing to swing around on the inside brake which is
still held at 1/4. To trim the circle to shape, dab on the
outside brake when you want to straighten up (you think the core
is in front of you), and release it again when you want to
tighten (you're in the core!), maintaining your weight-shift
throughout.
3.5 The Albatross, the Crow and the Eagle
The albatross is a huge bird which thermals
exceptionally well. Their technique seems to be to keep their
wing as level and rigid as possible. They use just a tweak of
their wingtip feathers and a slight shift in their wings to
initiate a turn. They are graceful and inspiring to watch. In
light, wide thermals they are masters. Their technique equates to
keeping the wing as level as possible, slowing the wing to
minumum sink on the brakes, and using very little weightshift,
maybe a gentle negative turn. Yet their technique doesn't work in
all conditions. When the air gets choppy, and the lift punchy,
scrappy and strong, their only hope is to link up many pockets of
lift in their wide circles, using their awesome glide angle to do
what paragliders can't. To hold onto the one, strong core
requires a change of approach, and this is where the crow comes
into its own. Swooping and carving, banking and climbing,
slipping their wings around in tight turns almost at the point of
stall, then swinging out in a joyous, speedy circle. This
technique equates to using lots of weightshift, flying fast and
actively, tightening your turns quickly when you feel lift,
throwing the glider around. Here I often abandon the negative
turn in favour of flying faster, just weightshift, then inside
brake to initiate the first, climbing turn.
The eagle, oh majestic master of the sky, blends the two techniques, and seems an albatross in the late afternoon mellow sky, and a crow at midday. The challenge of flying like an eagle is partly learning how to blend the Albatross and the Crow to get the most out of the sky you are in. The other part of the challenge is catching something for lunch.