Originally Posted by
BOAC
Less form drag and weight when 2 surfaces provide the same control forces as 3?
Not really. For two surfaces to provide the same forces as three, they have to be 50% larger. There's no magic extra force available with the surfaces inclined relative to a notional "aircraft vertical".
If there were really such a significant efficiency improvement, you can be damned sure there'd be a lot more V tails around - no-one's going to ignore a "free" performance improvement.