Why the T-Tail?

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
--
Marian Aldenhövel, Rosenhain 23, 53123 Bonn.
Fon +49 228 624013, Fax +49 228 624031.
http://www.marian-aldenhoevel.de
"I know you believe you understand what you think I said, but I'm
not sure you realize that what you heard is not what I meant."

"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.

It gets the elevator/ horizontal stabilizer up into cleaner air with fewer
flow blanking problems from the wing and fuze. Perhaps the biggest advantage is
that it gets the stabilizer up high away from damaging obstructions. I have
seen one low-down elevator get damaged in ground handling and it was not a
pretty sight.

Vaughn

What are the aerodynamic or constructive reasons for that?

Ciao, MM
--
Marian Aldenhövel, Rosenhain 23, 53123 Bonn.
Fon +49 228 624013, Fax +49 228 624031.
http://www.marian-aldenhoevel.de
"I know you believe you understand what you think I said, but I'm
not sure you realize that what you heard is not what I meant."

Pro T-tail: It's in the clean air.
Contra T-tail: Huge torque forces.

The torque forces are more easily mastered when the planes are small.
There are biz jets and turboprops with T-tails. On the other hand, all
serious acro planes, gliders included, have "conventional" tails.

Stefan

All the reasons below are valid.
The reduced interference drag between the vertical and horizontal stab is
one of the key factors. Note that the surfaces are aerodynamically off
set
relative to each other, as well it provides an endplate for the vertical
stab.
I would venture to say if the conventional tail would give a 1/2 more
performance we would still see that type of tail. Never mind ground
clearance
and other disadvantages.




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.

It gets the elevator/ horizontal stabilizer up into cleaner air with
fewer
flow blanking problems from the wing and fuze. Perhaps the biggest
advantage is
that it gets the stabilizer up high away from damaging obstructions. I
have
seen one low-down elevator get damaged in ground handling and it was not a
pretty sight.

Vaughn

What are the aerodynamic or constructive reasons for that?

Ciao, MM
--
Marian Aldenhvvel, Rosenhain 23, 53123 Bonn.
Fon +49 228 624013, Fax +49 228 624031.
http://www.marian-aldenhoevel.de
"I know you believe you understand what you think I said, but I'm
not sure you realize that what you heard is not what I meant."

On Tue, 26 Oct 2004 11:46:18 +0200, Marian Aldenhövel
wrote:


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?

A T-Tail has significantly less interference drag
(Interferenzwiderstand) than a conventional one. Since its weight is
located on top of the vertical stabilizer (Seitenflosse), fuselage
structure needs to be stronger, but the additional weight is
acceptable for a glider that needs to have as little drag as possible.


Bye
Andreas

The 'T' configuration gets the tail out of the way
of crops when field landing and consequently helps
to be prevent it from being ripped off! I should imagine
that this would be a rather expensive mistake?!

It also provides an end plate for fin and so potentially
reduces drag, although I'm not sure by how much.


At 11:06 26 October 2004, Stefan wrote:

Pro T-tail: It's in the clean air.
Contra T-tail: Huge torque forces.

The torque forces are more easily mastered when the
planes are small.
There are biz jets and turboprops with T-tails. On
the other hand, all
serious acro planes, gliders included, have 'conventional'
tails.

Stefan

What about the pilatus B4 then?

Rgds,

Derrick Steed

Additionally the T-Tail acts like a large Winglet on the end of the
vertical stab and improves the effectiveness of the vertical Stab and
Rudder. Also it only has 2 intersections as opposed to 4 on a
conventional tail. Plus it is easier to mount a one piece removable
stab on top rather than in the middle of the vertical stab.

Brian


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

Or even the Salto


At 12:48 26 October 2004, Derrick Steed wrote:
What about the pilatus B4 then?

Rgds,

Derrick Steed

What about the pilatus B4 then?

It has a T-tail too;-)

Seriously, every design is a trade off between structural weight and
performance issues such as wetted area and configuration.

The B-4 is an aerobatic glider with very good glider performance, about 35:1.
It has a shorter distance from wing to tail compared to most gliders and a
larger cross section. That allows the structure to handle the torsional forced
induced by the T-tail. In fact there are two models, one for limited
aerobatics, the other for full. The main difference is a stiffening plate at
the tail.

Jim Vincent
N483SZ
illspam