Hang Gliding and Paragliding Volume 44 / Issue 3: March 2014 | Page 55

MacCready speed ring, and now you
know where that term came from.
However, we now have instruments
with GPS functions that detect our
ground speed in all directions, feel our

it into our magic instruments. Most
modern high-end instruments have the
next-expected-climb function. So all you
have to do is sit back, read your instruments, do what it advises and plow

on a weak day. We need speed-to-fly.
That said, we also need to look at
some of the limitations. Hang gliders
and especially paragliders are sensitive
to the air’s ebb and flow and vertical

airspeed through a probe, diddle with
the math and come up with the actual
direction and speed of the wind at our
flying point. Then, assuming it has an
accurate graph of our glider’s performance at each speed, the instrument
does the figgerin’ and tells us precisely
and unimpeachably what speed to fly for
best performance.
But there’s more: The above method
perfects our flight in wind or calm, lift
or sink, but when thermals are around
and a pilot is in a hurry (setting records
or competing, e.g.), it is more efficient
to fly even faster than the speed that
provides the best path over the ground.
That’s because when you get to the next
thermal earlier and can climb in it, you
can make up for the altitude lost by
spending more time climbing. To use
this additional enhancement to speedto-fly, we need to be able to estimate the
strength of the next thermal and input

through the air, right? Not so fast...

changes. That means we bounce around
quite a bit and the speed-to-fly indicator (which indicates what airspeed we
should be flying for perfection) is always
telling us to change speed in active air
(thermal conditions). If you try to chase
the presumably correct airspeed you will
always be changing speed—putting in
control inputs—and that is bad for several reasons. First, there is inertia and a
delay between when you make a control
and when the glider adjusts its speed,
so you may never get it right. Secondly,
lots of airspeed changes can create
losses. Thirdly, when you are constantly
watching your instrument, or constantly
making conscious control inputs you
are not able to focus on the feeling and
decision-making necessary to minimize
your losses and find lift lines while
gliding, let alone find the next thermal
through sensation.
Sailplanes have a lot of damping in

REALITY CHECK
Understanding speed-to-fly concepts
and using them to the best of your ability is important for both recreational
and comp pilots. Since most readers are
floaters and boaters, let’s focus our attention there. If you are simply floating
around your home site, assuming you
are using thermals, every time you leave
a thermal you should be thinking speedto-fly. You usually have to get to another
thermal to stay up, so why not get to it
as high as possible so you can top out as
high as possible, or even more critical,
so you can get into the meat of it if it is
of finite vertical dimension (which most
are)? Losing extra altitude as you glide
to a thermal can mean the difference
between hooking it or looking up at the
other circling soarers. As little as 25 feet
of altitude can make or break your flight

HANG GLIDING & PARAGLIDING MAGAZINE

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