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29

Two reasons: T-tail design is often imposed on designs with twin engines mounted at the aft fuselage. This means they have a small moment arm in the yaw direction, the vertical tail is dimensioned to compensate for engine failure. The further away form centreline the engine is mounted, the higher the yawing moment that the remaining engine exerts upon ...


23

There is more to a T-tail than that: Aerodynamics: The placement on top of the vertical gives it more leverage, especially with a swept tail. Depending on wing location, it stays in undisturbed flow in a stall. Note: This is really depending on the details, the HFB-320 had a forward swept wing and a T-tail, which made a deep stall possible (and in one case ...


18

There's a lot to this, and I'm no aircraft engineer, so if there are any other answers, I'll happily delete this. Anyway, from what I've been told: The T-tail sticks the elevators out of the disturbed air of the wings, prop, and (usually most of) the fuselage which gives you better elevator authority, and makes a tail stall less likely. It has some ...


15

It comes down to a matter of philosophy. Or, if you are less generous, it’s a matter of fashion. Note that the Russian equivalent to the C-141, the Il-76, uses a T-tail, too, while the An-124 uses a conventional tail. T-tails were in fashion in the early jet age. They were widespread, first in fighters and later in transport aircraft, too, because they: ...


13

A horizontal tail on top of vertical tail would require strong and heavy structures, which in turn is not good for economics of flight. The bigger the plane is, the more challenging the loads the tail has to handle are, so what might be a feasible solution on a regional jet might not work at all for a large jet. T-tails are an obvious choice when the ...


11

Raymer gives the following answer: The 'T-Tail' is also widely used. A T-tail is inherently heavier than a conventional tail because the vertical tail must be strengthened to support the horizontal tail, but the T -tail provides compensating advantages in many cases. Due to end-plate effect, the T -tail allows a smaller vertical tail. The T ...


10

High wing military aircraft (c141 and c5 both are) use T tails for multiple reasons. to prevent rocks and debris from damaging the tail when landing off airport to keep tails out of the engine thrust line (which are higher than on a low wing aircraft) during cruise where vibration may cause fatigue a T tail can be smaller (lighter with less drag) as the ...


9

No. A t-tail would worsen the characteristics of the airplane. While not necessarily a horrible idea in its own right, the already-nasty slow-flight/high alpha/stall characteristics of the aircraft that necessitated MCAS in the first place would make this idea dangerous. The pitch-up tendency could lead to a stall, which in a T-tail can lead to a deep stall. ...


7

It's a "bullet fairing". Sometimes you get the pressure fields of the vertical and horizontal surfaces in alignment so the lowest pressure zone of the vertical fin is merged with the lowest pressure zone of the horizontal tail right at the intersection of the surfaces. It results in a more extreme pressure recovery aft and can cause flow separation and ...


5

The considerations in the roe's answer are entirely correct but there might be other factors to take into account. First, it is true that using conventional tail leads to the fact that the airflow over the tail might be disturbed by the main wing and/or the engines and/or the fuselage. However, the downwash induced by the main wing on the flow is taken into ...


5

The problem with the MAX has nothing to do with the elevators being ineffective, the characteristics which lead to the pitching up will be present wherever you put the tail. It's the placement of the engines that are the problem. Moving the tail would require big changes, you have to strengthen the tail and structure around it, which would be extremely ...


5

It might have something to do with the super stall phenomenon in which a stalled wing blankets a T-tail.


4

A primary reason is that it facilitates a large cargo hatch and ramp to be built into the rear of the plane, for loading and unloading. No elevator spar running through the middle of the rear of the aircraft to get in the way. Note that both the current C17 and A400m transports, very recent designs, also use a T tail. Both have large cargo hatches in the ...


4

As far as technical specifications are concerned, some explanation is: Excerpt from Wikipedia (formatting is mine): T-tail DESIGN: The horizontal stabilizer is mounted on top of the fin, creating a "T" shape when viewed from the front. PURPOSE: T-tails keep the stabilizers out of the engine wake, and give better pitch control. T-...


3

A T-tail has structural and aerodynamic design consequences. The structural considerations are of course the increased weight of the vertical tail due to now having to support the forces and moments on the horizontal tail, including strengthening for flutter. The vertical tail can be shorter due to the end plate effect of the horizontal tail, and the moment ...


3

In some aircraft, that protruding spike houses the high frequency comm antenna and its tuning mechanism. In others it contains parts of the elevator angle-of-attack control mechanism.


1

I worked on both aircraft for Lockheed (1967-1983). The reason for the T tails is a government requirement that the aircraft must be able to land in a depression or say wide ditch. The stabilizer must clear the required depression height. True I am 80 years old but my mind is clear enough to remember this. We did a tremendous amount of time in flight test ...


1

An end plate on a lifting surface (which the vertical tail is, during a yaw maneuver) reduces tip vortex formation, which means less lifting area is needed to produce the same lift force. It also significantly reduces induced drag, though the parasitic drag of the plate is usually a net loss unless, as in the case of a horizontal tail, the "plate" serves ...


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