ASI ALT VARIO AUDIO Static port Pitot tube Capillary Capacity flask Figure 4-29.  High end flight computer system. Figure 4-28.  An example of a Netto variometer system. The GPS-coupled flight computer can provide the following  information: valve. Pitot pressure pushes minute quantities of air through  the valve and into the reference chamber tubing. The effect  is  to remove the glider’s sink rate at various airspeeds from  the variometer indication (polar sink rate).  [Figure 4-28] Computerized (electronic) Netto variometers employ a  di ffe rent method to remove the glider performance polar  sink rate from the variometer indication. In this type of  system, sensors for both pitot pressure and static pressure  provide airspeed information to the computer. The sink  rate of the glider at every airspeed is stored in the computer  memory. At any given airspeed, the sink rate of the glider  is mathematically removed, and the variometer displays the  rate of ascent or descent of the air mass itself. Electronic flight computers are found in the cockpits of  gliders that are flown in competition and cross-country  soaring. Since nonpowered gliders lack a generator or  alternator, electrical components, such as the flight computer  and very high frequency (VHF) transceiver, draw power from  the glider battery or batteries. The battery is usually a 12- or  14-volt sealed battery. Solar cells are sometimes arrayed  behind the pilot, or on top of the instrument panel cover, to  supply additional power to the electrical system during flight  in sunny conditions. The primary benefits of the flight computer can easily be  divided into two areas: navigation assistance and performance  (speed) enhancement. Fundamental to the use of the flight computer is the concept  of waypoint. A waypoint is simply a point in space. The three  coordinates of the point are latitude, longitude, and altitude.  Glider races and cross-country glider flights frequently  involve flight around a series of waypoints called turnpoints.  The course may be an out-and-return course, a triangle, a  quadrilateral or other type of polygon, or a series of waypoints  laid out more or less in a straight line. The glider pilot must  navigate from point to point, using available lift sources to  climb periodically so that flight can continue to the intended  goal. The GPS-enabled flight computer aids in navigation  and in summarizing how the flight is going. When strong lift  is encountered, and if the pilot believes it is likely that the  strong lift source may be worth returning to after rounding  a turnpoint, the flight computer can mark the location of the  The primary components of most flight computer systems  are an electric variometer, a coupled GPS receiver, and a  microprocessor. The variometer measures rate of climb  and descent. The GPS provides position information. The  microprocessor interprets altitude, speed, and position  information. The microprocessor output aids the pilot in  cross-country decision-making. Shown in  Figure 4-29  is a  high end glider flight computer.  4-15 Electronic Flight Computers •  The optimum airspeed to fly to a location on the  ground, such as the finish line in a race or the airport  of intended landing at the end of a cross-country flight •  The optimum airspeed to fly to the next area of  anticipated lift •  How fast you are climbing or descending •  How high you need to be to glide there •  How fast you are going there •  Distance to planned destination •  Where you have been •  Where you are