STEMME S10 - 3. Description of Assemblies; 3.1 Cell, Primary and Secondary Structures

DOCUMENT NUMBER:
L400-912810 ISSUE AUG 20, 2016
AMENDMENT: 04
DATE: APR 04, 2022
APPROVED SECTION - PAGE 4-36
AIRCRAFT FLIGHT MANUAL STEMME S10, VARIANT S12
SLOW FLIGHT AND STALL BEHAVIOR IN GLIDER CONFIGURATION
Gliding and searching for thermals often requires ying at low speed.
When ying at mid and forward CG, minimum airspeed should be limited by
the aft stop of the elevator and only dynamic stalls (rapid pull-up) should
be possible. Indication of stall in glider conguration is by aerodynamic buf-
feting (in level ight and in turns), when vortices of separated airow from
the wing root area impinge on the tail surface. This aerodynamic bueting
occurs about 5-8 kph / 3-7 kt above stall speed. At rst indication of stall
warning (aerodynamic bueting) reduce elevator back pressure to reduce
angle-of-attack and increase airspeed.
If speed is not increased at stall warning onset and reduced further, the
aircraft may stall with a wing drop. Up until wing drop, aileron and rudder
are eective and correct; controllability is restored immediately, even during
stall, when elevator is released forward. An uncontrollable tendency to spin
has not been observed.
WARNING
Altitude loss for recovery from stall in level ight should be up to 30 m / 100 ft,
out of a turn up to 40 m / 130 ft and for a delayed reaction up to 60 m / 200 ft.
Minimum speeds are given in section 5.2.2.1 Stall and minimum speed in
glider conguration for unaccelerated straight and level ight. During turns,
depending on bank angle and corresponding g-load, minimum speeds are
higher.
Example:
Minimum speed and stall during steady turns with 60° of bank and a g-load
of 2, are expected to be higher by a factor of 2  1.4 compared to unaccel-
erated level ight.
Procedures to recover from unintended stall or spin are given in section
3.4 Stall Recovery and 3.5 Spin Recovery.