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m. Full-stall – Deep/Parachutal Stall
The available brake travel before stalling the wing depends on the size and the loading. For the
SUSI 4 is the minimum range of brake travel 55cm for size 14 and 16 / 60cm for size 18 / 65cm
for size 21 and 23 (at maximum load). Those numbers are just a rough indication. (The
publication of the brake travel is claimed by the EN 926-2.)
It would be dangerous to use the brake travel according to those numbers, because it is not
practicable to measure the brake travel during flight, and in turbulences the stall might occur
with less brake travel. If you want to use the whole brake travel of your glider safely, it is
necessary to do intended spins and full stalls to get a feeling for the stall behaviour –
preferable during a safety training course.
NOTE:
IN GENERAL THE BRAKE TRAVEL BECOMES SHORTER DURING A SIDE COLLAPSE (WHEN TRYING
TO STABILIZE ON THE OPEN SIDE)!
This is an extreme manoeuvre that should rarely, if ever, be required.
To induce a full stall, pull both brake-lines down smoothly. Hold them down, locking your arms
under your seat until the canopy falls behind you and deforms into a characteristic crescent
shape. In spite of how uncomfortable it may feel as the glider falls backwards, be careful not to
release the brakes prematurely or asymmetrically. If the brakes are released while the glider is
falling backwards the surge and dive forwards is very fast and the glider may shoot in front and
even underneath you.
In a full stall the canopy will oscillate back and forth. To stabilise this, the pilot can release the
brakes slowly and for approximately 1/3 of the brake travel and then hold at this level. Holding
at this position allows the wing to refill slightly across the span. When releasing the brakes
without pre-filling the ears mostly will most probably hook in the lines and this can result in a
cravat.
After pre-filling the glider stabilizes its movements and the brakes can be leased until the glider
recovers speed and flies again.
Only release the glider when it's in front or over head – never when the glider sits back of the
pilot.
ATTENTION: The full stall requires a lot of height and demands certain skills to recover. It is
important this manoeuvre is not practiced without qualified supervision.
It should preferably be practiced during a safety training course.
The deep stall, or parachutal stall is kind of the pre-stage to a full stall. The wing has no
forward motion and a high sink speed, but it is almost fully inflated. The pilot can enter the
deep stall by applying both brakes. It is very difficult to keep the wing in a deep stall: If you pull
the brakes a little too much, the glider will enter a Full Stall. If you release the brakes too much,
the glider will go back to normal flight. To practice a deep stall, it is necessary to master the full
stall first.
A very old or worn out glider with a porous cloth or with a changed trim (due to many winch
launches, or deep spirals) might stay in a deep stall even after releasing both brakes. Do not
apply the brakes in such a situation, because the wing would then enter a full stall! You can exit
the deep stall by pushing the speed bar, or by simply pushing the A-Risers forward. If you fly
through rain, the risk of a deep stall is higher.
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