Remote Indicating Thermometers are normally used in airliners operating at higher speeds. In our earlier post we had learnt about the Direct Reading Thermometer that are used in slow speed aircrafts.
WHETSTONE BRIDGE
The Remote Indicating Thermometer measures temperature using the principle of change in electrical resistance with temperature. Whetstone’s bridge is used in this type of thermometer where one part of the circuit is exposed to outside air while the other is placed inside the aircraft. Whetstone’s bridge measures flow of current in circuit due to by imbalanced resistance which can be calibrated to read temperature.
Remote indicating thermometer has a major advantage over direct indicating thermometer. This form of thermometer provides temperature information in electrical form which can be transmitted to other instruments and aircraft systems.
Till now, we have discussed about the various types of thermometers, In our next lesson, let us understand about construction of the Total Air Temperature Probe. Total Air Temperature Probe or TAT Probe is the part which is fixed outside the aircraft for obtaining indications on a Remote Indicating Thermometer.