The Glider's Instruments

The photo below shows the front instrument panel of one of the club's 2 seat training gliders.

The airspeed indicator shows the glider's speed in Knots (nautical miles per hour). Unlike a car speedometer the pointer can rotate more than one full revolution. With the glider on the ground here, the needle reads zero but, on the inner ring it could be reading 114 kts. The maximum speed of the glider is shown with a red mark, in this glider 134kts.

The 2 variometers, one mechanical and one electric, show the rate of climb (needle moves up above zero) or descent (needle moves below zero). These are the instruments used to 'soar' the glider. (See 'How the Glider Soars')

The altimeter has 3 needles, in this photo 2 are hidden behind the large needle. The largest needle indicates hundreds of feet, so if it were pointing at 5 the glider would be at 500'. The next, slightly smaller needle indicates thousands of feet in exactly the same way and the third, smallest needle, tens of thousands of feet. This can be seen in the second photo below.

The G meter or accelerometer shows the G forces on the glider. Sitting on the ground we all experience the force of gravity, 1g, but during aerobatics or in turbulent air forces greater or less than 1g can be experienced. The meter has, again 3 needles. One moves in response to changes in the G experienced and pushes the others to show the maximum and minimum levels reached. This is also shown on the second photo.

The radio can be set to different frequencies to allow communication with other gliders, ground stations and air traffic controllers. The radio below is set to 130,100MHz, a dedicated frequency for gliders.

The compass shows the direction the glider is pointing, in this case around 110 degrees, 20 degrees South of East. The compass rose floats to allow it to remain level. In this photo the glider is parked with a wing down hence the compass rose does not appear level.

The second photo, below, shows the instrument panel of single seat glider in flight.

The top left instrument is the G meter. It is reading 1g at present (middle needle) but shows that the glider has experienced + 2.3g (top needle) and 0.5g (bottom needle)

The top right instrument is the radio, again set to 130.100Mhz but with a 'standby' frequency of 130.125Mhz also selected.

The top centre and bottom left instruments are the mechanical and electric variometers respectively. They both indicate the glider is climbing at around 2kts. Because the electric variometer can react faster there are slight differences in the readings. The large instrument with the rectangular screen in the centre of the panel is a flight computer linked to the electric variometer and also (not seen) a GPS satellite navigation system. It provides a lot of information for the pilot. Here it shows an average climb rate of 1.9kts, an altitude of 17260' above sea level and a Head Wind of 51.2kts (!). The GPS has been set to provide directions to a waypoint and the headwind is calculated for flying towards the waypoint. To fly to the waypoint the glider would need to be turned 90 degrees right (the 90 on the display, a -90 would indicate turning left). The central bar on the left has PULL above it and PUSH below telling the pilot to pull or push the stick to fly at the optimum speed. Graduated bars appear above or below the central line to indicate how far off optimum speed you are. At present there are none showing, the glider is at the correct speed. This is 42kts, indicated by the airspeed indicator to the right.

The central instrument below is a turn and slip indicator for cloud flying. The needle indicates the rate of turn (none shown) and the ball should remain central if the glider is flown correctly. The red string on the canopy above the instrument panel also shows if the glider is being flown accurately, it should be straight up the canopy. The top of compass can just be seen below the red string but cannot be read in this photo.

The bottom central instrument is the altimeter. It is reading 16950', in this instance above take off height rather than sea level. The small sub-scale on the right side of the instrument can be set to allow the altimeter to read zero on the ground or a particular height or can be set to an air pressure of 1013mB which is the standard pressure used to calculate heights. The small hand indicating 10s of thousands is between 1 and 2, the middle needle shows nearly 7000' and the large needle 950'.