Stick thermal
Encyclopedia
Stick thermal is terminology used in aviation
, and particularly in the sport of gliding
. It refers to the illusion that the glider is climbing in a thermal when, in fact, the upward movement of the glider is caused by nothing more than the pilot pulling backwards on the control stick.
It is useful for a pilot to know the rate of climb of air in a thermal
. They can use this to find the strongest area of lift in the thermal
. A variometer
can be used to measure the rate of ascent of an aircraft. However, a simple variometer
does not actually measure the lift in the thermal, it measures the rate of ascent of the aircraft. So a pilot may be inside a thermal that is moving upwards at 2 metres per second, but the pilot may be diving their aircraft at 2 metres per second. So the variometer shows zero rate of climb, and does not indicate the presence of the thermal.
A total energy compensated variometer will show the actual rate of climb of the thermal, regardless of the movement of the aircraft.
A stick thermal is where an uncompensated variometer
indicates that an aircraft is ascending or descending due to pilot input (the joystick
).
The pilot may believe he is in a thermal as the variometer indicates that he is ascending, but in fact he is ascending due to his own control of the aircraft.
Aviation
Aviation is the design, development, production, operation, and use of aircraft, especially heavier-than-air aircraft. Aviation is derived from avis, the Latin word for bird.-History:...
, and particularly in the sport of gliding
Gliding
Gliding is a recreational activity and competitive air sport in which pilots fly unpowered aircraft known as gliders or sailplanes using naturally occurring currents of rising air in the atmosphere to remain airborne. The word soaring is also used for the sport.Gliding as a sport began in the 1920s...
. It refers to the illusion that the glider is climbing in a thermal when, in fact, the upward movement of the glider is caused by nothing more than the pilot pulling backwards on the control stick.
It is useful for a pilot to know the rate of climb of air in a thermal
Thermal
A thermal column is a column of rising air in the lower altitudes of the Earth's atmosphere. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and are an example of convection. The sun warms the ground, which in turn warms the air directly above it...
. They can use this to find the strongest area of lift in the thermal
Thermal
A thermal column is a column of rising air in the lower altitudes of the Earth's atmosphere. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and are an example of convection. The sun warms the ground, which in turn warms the air directly above it...
. A variometer
Variometer
The term variometer also refers to a type of variable transformer or an instrument for measuring the magnitude and direction of a Magnetic field....
can be used to measure the rate of ascent of an aircraft. However, a simple variometer
Variometer
The term variometer also refers to a type of variable transformer or an instrument for measuring the magnitude and direction of a Magnetic field....
does not actually measure the lift in the thermal, it measures the rate of ascent of the aircraft. So a pilot may be inside a thermal that is moving upwards at 2 metres per second, but the pilot may be diving their aircraft at 2 metres per second. So the variometer shows zero rate of climb, and does not indicate the presence of the thermal.
A total energy compensated variometer will show the actual rate of climb of the thermal, regardless of the movement of the aircraft.
A stick thermal is where an uncompensated variometer
Variometer
The term variometer also refers to a type of variable transformer or an instrument for measuring the magnitude and direction of a Magnetic field....
indicates that an aircraft is ascending or descending due to pilot input (the joystick
Joystick
A joystick is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling. Joysticks, also known as 'control columns', are the principal control in the cockpit of many civilian and military aircraft, either as a center stick or...
).
The pilot may believe he is in a thermal as the variometer indicates that he is ascending, but in fact he is ascending due to his own control of the aircraft.