Advance acoustic SIGMA8, User Manual

Page: 11 / 40

11
The SIGMA 8 has a speed system with a Speed-Performance-Indi-
cator (SPI), which reads off against 2 positions on the backs of the C
risers (30% and 80% positions). The red markers on the speed sys-
tem enable a precise speed bar position to be set to suit the in-fl ight
situation. Thanks to its well-behaved pitching qualities the SIGMA 8
can also be accelerated without problem in light turbulence. Because
of its high performance in accelerated fl ight the choice of speed-to-fl y
plays a very important part in obtaining the best gliding performance.
Each of the SIGMA 8 SPI positions has a value for headwind, expect-
ed climb and sink rate. These indicated positions are effective for on-
ly one of their three values, taken in isolation - considered by itself.
This means that either the headwind, or the expected rate of climb,
or the sink rate applies to that position. The SPI principle is based on
the simple (using headwind and sink) and the extended (including ex-
pected climb rate) McReady Speed-To-Fly theory.