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Calling E EnginemanDuring a conversation I had with dad's navigator he mentioned that dad had been given the somewhat "derogatory" nickname "Coring Cave". During a recent conversation I had with a colleague, he mentioned a pilot on a 6-Group Halifax squadron had to return early on one occasion because one or more engines had been subject to "Coring", due to extreme icing conditions, and that the intakes of the engines had been caked with ice.
So what exactly is "coring"?
Jim
Hi,
Yes, float-type Carburettor icing is possible in air temperatures upto about 30 degrees C, due to the cooling effect of gasoline evaporation freezing water vapour in the air. This problem probably contributed to many aircraft losses. The "Halifax" came in types with Merlin and Hercules engines. Those with float-type carbs would suffer carb icing. Later engines may have had Bendix or RAE-Hobson injection carbs that were very much less likely to get carb icing. However, never say never, some icing in flight can effect the intakes.The carburettor air-intake heat control is meant to allow the pilot to clear any carb ice. In practice it is very hard to detect carb icing, as it can form at temperatures above freezing due to the carb venturi dropping the temperature & pressure in the throat. There are charts which show likelihood of carb icing, such as this: https://www.aopa.org/-/media/Images...dent-Reports-Carburetor-what/nyc02fa025_1.jpg.
For airframe ice to form, you need visible moisture and temperatures below freezing. This would include oil coolers.
The Halifax only had an air temperature gauge. If the icing buildup is particularly bad, the carb heat will be incapable of clearing the ice. Once the engine stops, the residual engine heat typically melts the carb ice - but in nasty conditions it may never clear.
From the Halifax manual:
View attachment 762567
Yes, float-type Carburettor icing is possible in air temperatures upto about 30 degrees C, due to the cooling effect of gasoline evaporation freezing water vapour in the air. This problem probably contributed to many aircraft losses. The "Halifax" came in types with Merlin and Hercules engines. Those with float-type carbs would suffer carb icing. Later engines may have had Bendix or RAE-Hobson injection carbs that were very much less likely to get carb icing. However, never say never, some icing in flight can effect the intakes.
Eng
To avoid lead fouling, the engines should have been run at high power for a few minutes every now and then.This is interesting as dad had considerable difficulties with the aircraft equipped with the Merlin 38 engines during his operations in February 1945. On his operation to Dresden, all engines gave trouble and he was constantly feathering and restarting engines in sequence throughout a very long trip. His Base reported difficulties with lead-fouling of spark plugs, but these had supposedly been resolved by this time.
Jimt