Quote:
will taxi on hot,
Although I agree with the rest of your post, this seems to be an exceedingly bad idea. In all of the aircraft I have flown, setting carb heat to hot also bypasses the air filter. This means that debris thrown up by the propellor, such as sand and gravel, can enter the engine without being filtered out. This can lead to all sorts of damage to valves, pistons, cylinder walls and so forth. Not good.
I realize that there are situations where taxiing without carb heat will lead to almost instant carb ice, and in that case you have no choice but to apply carb heat, or abandon the flight altogether. But to taxi with carb heat on by default, even when not required, sounds like an invitation to very costly damage.
Perhaps I didn't make it clear - I do that whenever I feel that conditions warrant it. On ordinary days when the risk is less then I don't.
One incident happened on a summer's day at lunchtime when the group temperature was in the high 70s. After taxying to the hold, I was kept waiting for over 5 minutes using carb heat for a lot of the time and increasing power to keep the engine warm. Even then, as I started the take-off, I lost power in the initial climb so put her back on the ground in short order.