Windtech evo - Manual (Page 17)

17
It is NOT recommended to induce a spiral dive at the same time as applying any thrust
or power from the engine, as this could result in instability.
-- b-line stall
SET TRIMMERS TO NEUTRAL POSITION
To induce a ‘B-line” stall, first take hold of both ‘B’ risers (left and right) one in each hand
(left and right respectively) FIRMLY at the maillons. Then, pull the B-risers down togeth-
er to approximately the level of the karabiners, BEING VERY CAREFUL TO DO THIS SYM-
METRICALLY so as to
not induce a spin.
This will “B-stall” the
glider, by deforming
the aerofoil section
of the wing in such a
way as to stop the
airflow going over it
as normal, effectively
‘breaking’ the aerofoil
effect. If done cor-
rectly, the glider will
now enter into a “B-
line stall”, which is a
kind of “parachutal”
stall, stopping the glider flying and rendering one’s trajectory effectively straight down
through the air (BUT DRIFTING WITH THE WIND). Once in the “B-line” stall one can con-
trol the descent rate to a degree by pulling down more or less on the B-risers and it is
possible (in still air) to achieve descent rates from 5-11 m/s. BE CAREFUL, AS PULLING
DOWN TOO FAR ON THE B-LINES CAN CAUSE THE GLIDER TO BECOME UNSTABLE, SO
THIS SHOULD BE AVOIDED.
To exit from the B-line stall correctly, and minimise the chance of any instability, the
pilot should keep a firm hold of the B-risers and raise them until there remains 10cm of
travel of the B-risers and then release them completely, taking care to do this SIMULTA-
NEOUSLY. If the B-line is entered, or released, asymmetrically, it is possible to enter a
spin, and so this should always be avoided. Once the B-risers have been released in the
correct manner the glider will return to normal flight spontaneously with a small dive as
it regains “healthy” airspeed.
Obviously, one should never do a B-line stall at the same time as engaging any thrust or
power from the engine as this could result in unstable situations which could lead to
dangerous loss of control.