Spiral dive, B stall – Windtech impulse User Manual

Page 13

Advertising
background image

13

To recover, release the outer 'A' lines & the IMPULSE will return to normal flight.

-- spiral dive

The Spiral dive is performed by starting a series of 360 degrees turns, gradually pulling
one brake harder and harder and weight shifting into the turn. Pull more inside brake,
and weight shift harder, for a faster spiral dive. Ease off on the inside brake, and weight-
shift less hard, to regain level flight. Like this, the pilot can control the bank angle and
the sink rate of the glider in the Spiral dive. Always remember that whilst in the Spiral
dive you are drifting with the wind, and it is very easy to become disorientated.

This manoeuvre is not approved for bank angles higher than 60 degrees. At this upper limit
the sink rate of the canopy is approximately 10 m/s and the wingloading equal to 2G's.

For bank angles higher than 60 degrees the sink rate can reach 20 m/s but the greater
wingloading (G's) can cause eyesight and equilibrium problems, and cause some people
to 'black out' (faint), which consequently can make the manoeuvre extremely dangerous.

To recover from a spiral dive, the inner brake must be progressively and slowly released,
until the canopy assumes normal fligh. A good rule of thumb is to use the same number
of 360-degree turns as you did on entry, when exit you, to give a safe and progressive
recovery. If you release (hands up) from a tight spiral dive you will experience a big surge
followed by a dive. (In turbulent air this can result in a collapse.) The IMPULSE has been

tested for this but it is advisable to learn the correct exit method, i.e. progressively
release the inside brake.

-- b stall

The B-line stall is a real stall, and even though the wing appears to be flying above your
head the laminar airflow over the wing is completely lost. During B-Stall, the canopy
decens perpendicularly to the ground (straight down, but drifting with the wind) at a sink
rate of 5 to 12 m/s, with an angle of attack of 90 degrees.

To enter a B-Stall, it is necessary to sit upright in your harness, reach up with the brakes
still in your hands (possobly with the toggles around your wrists) & securely clutch each
B risers in each hand at the top near the Maillons Rapides (quick links). To enter the B-
line stall, pull down symmetrically on the B risers. (About 40 cm)

The force initially is quite hard (for about the first 15cm) but for the last part the force
required to pull down is less. Keep your weight centred in the harness, and keep the ris-
ers held at a symmetric level to each other. The more B riser pulled the faster the decent
rate, but the glider can become unstable with a very deep B-line stall.

To return the glider to normal flight conditions:

Ease up the B-risers

SYMMETRICALLY and rapidly release them.

Releasing the B-lines from a deep B-line position works fine (& if unsure whilst attempt-
ing the manoeuvre simply release the B-lines together from this position) but puts

Advertising