by solostax » Sat Nov 10, 2018 7:12 pm
Microlights use engine CHT (cylinder head temperature ) and or EGT (Exhaust gas temperature) probes that are self powered.These are "K" type thermocouples that work on the principle that the thin probe combines two dissimilar metals. This when when heated will produce a voltage.This voltage is proportional to the temperature and is reliable.The gauge is 2"diam but would require a seperate power supply if dial face illumination is required.
Because the consequences of an overheated engine in aerial use could be serious ,the early two stroke engines were closely monitored in flight.Wisdom had it that of the two warning systems ,CHT or EGT, it was the EGT that was more important ,in that it showed an instantaneous temperature rise as opposed to the CHT that critically lagged . If in flight an oil seal or carburetor malfunction occurred the EGT could give adequate time for a forced landing with reduced power as opposed to total seizure.
I see many parallels in the use of using a 2 stroke microlight engine (Robin,Rotax,Cyuna etc) being hard pressed to deliver absolute maximum power for sustained periods and tuned Lambretta engines.
I see these instruments cropping up now and then on ebay and suggest they would be an ideal solution to engine temperature monitoring.