Finn Lassen wrote:

Hi Paul,

I think it's time for me to resubscribe and ask the list members a question.

After a long wait, the FAA finally graced me with their presence and
inspected my 13B powered RV-3 prior to considering issuing an airworthiness
cert.

My carb set-up is similar to Tracy Crook's old set-up: three Mikuni constant
velocity carbs. The inspector objects to me not having carb heat. I could
only tell him what Tracy had written and told me; that these carbs are not
subject to carb icing and that Tracy had been flying them for 500 hours
without icing problems. Also the Rotax 912 uses similar carbs and do not have
carb heat in many planes using them. Apparently the Kitfox does, though. The
inspector pointed out that the certified Diamond Aircraft Katana (spelling?)
using the Rotax 912 does have carb heat.

If I understood it right, Tracy's explanation is that the variable venturi
formed by the slider does not generate the same high pressure drop that
"normal" carbs do.

Can anybody point me to an authoritative source (other than Tracy) that
explains why constant velocity carbs are not subject to icing?

Finn

Congratulations Finn. Rotaries are now starting to come on-line. 

Put carb heat on it anyway just to be on the safe side.

Paul Lamar
 
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