User manual

ASK21, ASK21 Mi 1.00 Manual
Page 7 of 16
The Total Energy Compensated variometer provides that information "It shows the vertical speed while effects of
aircraft maneuvers are eliminated. For a mechanical vane vario this is achieved by using special static pick-up nozzles
which combine static pressure and pitot pressure". Perhaps best explained with these examples:
 Speed constant, altitude descending -> TEC variometer will read SINK
 Speed constant, altitude climbs-> TEC variometer will read CLIMB
 Speed increase, altitude constant -> TEC variometer will read CLIMB
 Speed decrease, altitude constant -> TEC variometer will read SINK
The SDI C4 also provides an audible indication of the Total Energy climb rate,
with a broken beep-beep-beep indicating lift, and a continuous beep indicating
sink. You learn quickly to recognize and respond to these sounds, speeding up
when you hear sink and slowing down when you hear lift. This behavior (called
'dolphin flying') makes a huge difference to the efficiency of your cross-country
flying. Please note that the McCready ring on the variometer in the TEC
variometer on our panel cannot be used. The information it can offer is
presented far more detailed and reliably by the C4 Competition.
NETTO VARIOMETER
The electronic 'vario SC' variometer above and to the left of the SDI C4 in the
Aerosoft Discus has been configured to continuously display the 'Netto climb
rate', operating as a slave dial driven by the SDI C4. It is a modified Total Energy
variometer (see above) with one additional compensation where the intrinsic
sink rate of the glider is also compensated. Thus, this vario shows basically the
ascent and descent of the external air mass. As the intrinsic sink rate is
obtained from performance data of the glider, this works well only as long as
the performance of the real glider is not reduced, e.g. by flies or water drops
on the wings - in this case there is a setting within the main SDI C4 flight
computer where you can adjust its value for the glider performance of the
glider, to restore the accuracy of the Netto reading (see the SDI C4 manual
included in this package).
While the calculation to provide the netto value is complex, the reading of the gauge is the most simple of all: if the
needle goes up it means the air outside the glider is rising, and similarly for sink. For ridge flying the gauge comes into
its own, continuously indicating the nuances of the vertical air movement as the wind passes over the hilly terrain,
allowing you to optimize your flight relative to the landscape.
ELECTRIC VARIOMETER – FLIGHT COMPUTER
The main 'petal lcd' gauge of the SDI C4 displays the total energy climb reading by default (see above). However, the
"VARIO/SOLLF." switch lower down on the panel allows you to switch the gauge into the most advanced mode of all,
i.e. "speed-to-fly".
As mentioned earlier, the pilot learns to speed up when the total energy variometer is indicating sink (to fly quickly out
of the sink) and to slow down when lift is indicated (to loiter in the lift to take the most advantage of it). But with a
total energy or netto variometer the pilot does not necessarily know how much to speed up or slow down. Indeed you