PPRuNe Forums - View Single Post - When's it too cold for Carb Heat?
View Single Post
Old 23rd Mar 2006, 18:23
  #7 (permalink)  
headsethair
 
Join Date: Apr 2002
Location: UK
Posts: 593
Likes: 0
Received 0 Likes on 0 Posts
FB: don't get carried away with "temperature" or you might end up being carried away in bits from your 22. The physics of the carb are mightily complex because of the inter-relationship between air temperature, humidity, speed of airflow, temperature of the fuel, air pressure. There are 2 places where ice can form - the butterfly and the venturi. And the ice forms in those places for different reasons.

Icing on the butterfly is easily dispersed with a little heat, but venturi icing can be a major blockage. As I said above, the acretion of ice in the venturi means that the airflow is actually speeded-up - which you would think is a good thing. But the volume of the air is decreased, and so the mixture gets too rich and cuts the engine.

Butterfly icing is a little simpler - it freezes the throttle control.

I can't quite understand your interest in this from a flying point of view. Are you one of those whackos who experiments with leaning at altitude whilst flying your heli ?

Be better if you conducted some carb icing experiments on an old BSA Bantam or some other low-flying carbed beast.
headsethair is offline