Re: Dihedral on Horizontal Tail Surfaces

Date:         30 Nov 98 03:07:50 
From: (SteveK1957)
Organization: AOL
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Dihedral in both wing and tail increase the tendency for the airplane to roll
due to sideslip which can agrivate Dutch Roll.  The same tendency is caused by
wing and tail sweep.  I suspect the reason for dihedral in the airliner
horizontal tails has more to do with getting the tails out of the wing wake to
reduce tail buffet than increasing the roll tendency.  There is usualy plenty
of roll due to sideslip in most airliners.  The F-4 has the anhedral in the
tail to counter the dihedral in the outboard panels of the wing which were bent
up for ground clearance on carrier decks.
Steve Koontz
Aerodynamic Stability and Control