Thread: Why the T-Tail?
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Old October 28th 04, 03:48 AM
JonB
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Marian Aldenhövel wrote in message ...
Hi,

I have noticed that most if not all modern gliders are built with a
T-Tail (not sure about the term, I am talking about the elevator being
located at the top of the tailfin). While most power-aircraft I know
right up to the airliners have it at the bottom.

What are the aerodynamic or constructive reasons for that?

Ciao, MM


It's nothing to do with aesthetics. It's just a happy coincidence
that aerodynamically efficient structures are beautiful things (and
not just for gliders).


Three reasons that may be significant are that:

1) The stabiliser is likely to be raised above the level of any crop
that the pilot may land in - therefore it will not be removed by
injudicious field-selection.

2) Also, I think I have read that a T-tail configuration produces one
less vortex than a conventional tail arrangement:- a vortex is spawned
from the end of each free tip of a tail surface (stabiliser or rudder)
therefore the top of the fin will not produce a vortex in a T-tail
arrangement (as the stabiliser prevents the fin from having a free
tip in the air stream). A vortex causes drag, therefore a T-tail will
be marginally more aerodynamically efficient.

3) Spin recovery is easier when the stabiliser is not in the
turbulence of a spinning main-plane - as is more likely to be the case
with a T-tail. Therefore a T-tail may be a safer aeroplane for
low-time pilots.



Jon.