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Page 3: Engine photos
-- Zodiac C-GZDC
Sorry, I never got much done in this section.
Main (coolant) radiator, before and after the ductwork was added The main rad was bought from Flypass, in place of the normal rad supplied with the kit. Flypass had been putting their rads inside the cowl, but it was up to the builder to design their own system to mount the rads and supply air ducts.
The main rad is tucked in behind the left side of the Rotax 912. The upper part of the rad is supplied with air from the main cowling intake, aided by ducting that seals against the cowling. However, it does not seal tightly around around the complex shape of the engine itself, which must also be free to move. The lower part of the rad is supplied with air supplied from a cheek inlet we added to the supplied lower cowling. The second picture does not show the metalwork all that clearly, but it is the best photo available.
Air exiting the rad is directed downwards (with slightly more ducting than seen in the photo). The bottom of the lower cowling has been modified to have a greater exhaust area away from the aircraft centerline, below the radiators in particular.
Cooling effectiveness:
The current configuration does not cool as well as is desired, and modifications are being considered. Areas being considered are better exit ducting (in-cowl pressures to be investigated), and the possibility of separated flow in the sharply expanding lower intake duct. The CHT levels are always moderate, never above 210 F on the ground or in the air during summer weather of 25-30 C. Such CHT temps are lower than what some others have reported for their Zodiacs with in-cowl rads, after a climb-out in hot weather.Many Rotax operators use CHT to indirectly monitor the coolant temperature, however we have an coolant temperature probe at the top of the radiator. The coolant temperature itself would often rise to 225 or 230 F after a 1000' to 1500' climb-out in summer. The temperature would continue to rise unless power was reduced or the aircraft levelled off for increased speed. I have not let the temperature go over 240 F. Idling on the ground longer than, say, 15 minutes could also result in the coolant reaching 230 F, although a strong head wind can prevent the steady temperature rise.
Rad frontal dimensions: Total is 5" by 14" = 70 sq. in.; finned area only is 11 1/4" by 4 3/4" = 54.4 sq. in. Weight 5.5 lb (not an aluminum rad).
Oil radiator, before and after ductwork was added As with the main rad, the oil rad was bought from Flypass. The somewhat bulky shroud seals against the cowl on three sides, but does allow air to escape around the engine cylinders.
The rad dimensions and ducting have been sufficient to keep oil temperatures below 230 F in the summer.
Rad frontal dimensions: 3" by 11" = 33 sq. in.
