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I’ve always wondered this. Why do gliders use a T-style tail, as opposed to a V-tail ie a swallow tail design? I think it would represent a significant reduction in weight over a conventional empennage, not to mention, offering a reduction in drag.

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    $\begingroup$ Because the swallows needed them and would not give them up :) $\endgroup$ Oct 2, 2023 at 18:28

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The V-tail was a trend in glider design between the late Fifties and the early Sixties. High-performance gliders like the HKS-1, the Arlington Sisu 1A$^*$, the SB-5, the Standard Austria or the Schempp-Hirth SHK had them, as well as the aerobatic H-101 Salto.

However, eventually the T-tail became the preferred choice for these reasons:

  • The endplate effect of the horizontal allows to make the vertical about 20% smaller.
  • A T-tail will suffer the least damage in an outside landing.
  • The effectiveness of a V-tail is lower for the same area, especially in damping.
  • V-tails are not really better in terms of drag reduction.

$^*$ Added thanks to the helpful advice by Thomas Perry.

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    $\begingroup$ A friend had an Austria glider with unusually large all-flying V tail surfaces and anti-servo tabs. He said it was actually deficient in rudder authority, making it a challenge in x winds. $\endgroup$
    – John K
    Oct 2, 2023 at 15:42
  • $\begingroup$ @JohnK Name me one glider which isn't deficient in rudder authority at low speed. They all are, more or less. Fly fast enough and things become fine, though. $\endgroup$ Oct 2, 2023 at 19:21
  • $\begingroup$ @PeterKämpf ...and I am going to add, the enigmatic Sisu 1A, if that is ok with you... $\endgroup$ Oct 3, 2023 at 16:00
  • $\begingroup$ @ThomasPerry: Thank you, that is a very welcome addition! $\endgroup$ Oct 3, 2023 at 19:59
  • $\begingroup$ @PeterKämpf Thank you, Peter. Your acknowledgement is very kind. $\endgroup$ Oct 6, 2023 at 16:50

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