pilot values in front and dual pilot values for the second seat  instrument. Marked for specific aircraft, some may have  empty ballast and full ballast values.  A popular type of total energy system consists of a small  venturi mounted in the air stream and connected to the static  outlet of the variometer or simply as a slot or pair of holes on  the back side of a quarter inch vertical tube. When airspeed  increases, more suction from the venturi moderates (offsets)  the pressure at the static outlet of the variometer. Similarly,  when airspeed decreases, reduced suction from the venturi  moderates (offsets) the pressure at the static outlet of the  variometer. If the venturi is properly designed and installed,  the net effect is to reduce climb and dive indications caused  by airspeed changes. To maximize the precision of this  compensation effect, the total energy probe needs to be in  undisturbed airflow ahead of the aircraft nose or tail fin (the  "Braunschweig tube", the long cantilevered tube with a kink  in the end that can be seen projecting from the leading edge  of the tail fin on most modern sailplanes.)  [Figure 4-27] Another type of total energy system is designed with a  diaphragm-type compensator placed in line from the pitot tube  to the line coming from the reference chamber (thermos or  capacity flask). Deflection of the diaphragm is proportional to  the effect the airspeed change has on pitot pressure. In effect,  the diaphragm modulates pressure changes in the capacity  flask. When properly adjusted, the diaphragm compensator  does an adequate job of masking stick thermals.  [Figure 4-28] A variometer that indicates the vertical movement of the air  mass, regardless of the glider’s climb or descent rate, is called  a Netto variometer system. Some Netto variometer systems  employ a calibrated capillary tube that functions as a tiny  A variometer with a total energy system senses changes in  airspeed and tends to cancel out the resulting climb and dive  indications (stick thermals). This is desirable because the  glider pilot wants to know how rapidly the air mass is rising  or descending despite changes in airspeed. Variometers are sensitive to changes in pressure altitude  caused by airspeed. In still air, when the glider dives,  the variometer indicates a descent. When the glider pulls  out of the dive and begins a rapid climb, the variometer  indicates an ascent. This indication is sometimes called a  stick thermal. A glider lacking a compensated variometer  must be flown at a constant airspeed to receive an accurate  variometer indication. Figure 4-27.  A total energy variometer system. Figure 4-26.  The MacCready ring. Total Energy System Netto ASI ALT VARIO AUDIO 0 2 2 4 4 6 6 8 8 10 10 2 0 4 6 8 10 2 4 6 8 10 20 18 16 14 12 10 Static port Pitot tube Tubing to total energy probe Capacity flask Total energy probe which regulates pressure at the static outlet of the variometer 4-14