Quote:
Originally Posted by Sutts
Is it true that the merlin had inbuilt and continuous carb heating? Any period refs you can point me to please?
The reason I doubt this point is the same reason carb heat is usually controlled by a switch/lever in the cockpit - heating the air going into the carb reduces engine power as warm air is less dense than cold air so you get less air going into the cylinders to burn with the fuel. This is the same reason compressed air from the supercharger is often cooled before it gets to the carb (to remove the heat created during compression).
Now I can't see the designers of the merlin permanently reducing engine performance by continuously heating the air entering the carb.
On the other hand, if just the carb body is heated then I suppose the effect on the air might be insignificant. Would be nice to see some docs on the subject.
Cheers
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The Merlin variants as modelled in COD are NOT subject to carburettor icing thats why no Carby heat or controls are present... they are not required.
How can this be ? Well the designers thought about it right from the word go. The SU twin barrel carburettor throats are jacketed. The Jackets around each carburettor throat were fed with Hot return flow engine coolant before it got to the radiator. This ensured that the Carby throats (and therefore butterfly) were always warm and prevented the formation of carburettor icing. See jpg of the carby. Item 18 shows the jacketing and warm fluid flow as the purple shading. The mounts for the Internal butterfly valves were also fed with warm scavenge oil shown in red.
From this Pub:
When rough running in cloud was discussed with the devs they indicated that it was caused by Propeller icing. Though IMO more work on conditions conducive to icing needs to be done in COD. In addition if we are seeing propeller icing then Airframe icing should be an issue as well ... it isnt at the moment. We see Ice build up on the canopy but not the airframe.