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38 votes
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Why are airplanes parked at the gate with max rudder deflection?

The control surfaces of airliners are not connected to the pilots' control via cables; they are operated by a hydraulic pump. When the engines are shut down, there is no hydraulic pressure in the ...
kevin's user avatar
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30 votes

Why do T- tail airplanes have a shorter vertical stabilizer?

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 ...
Koyovis's user avatar
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26 votes
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Why don't commercial aircraft use all-movable tail surfaces like my RC plane?

What is better and easier for small-scale models is not necessarily better for larger aircraft. First, you can't say that the fixed part "does nothing". The tail is primarily a stabiliser; without it,...
Zeus's user avatar
  • 9,083
24 votes

Why don't airliner vertical tails extend to the very aft of the fuselage?

Spin resistance and area ruling Locating the vertical a bit ahead of the horizontal tail brings it out of the probable wake of the horizontal at high angle of attack, so it still is effective in ...
Peter Kämpf's user avatar
22 votes

Has there ever been a sideways H-tail on an airplane?

Most of the initial aircraft made by Wright brothers had the twin horizontal stabilizer setting. However, the elevators in these cases were set in the front, rather than back, as is the norm now. By ...
aeroalias's user avatar
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21 votes
Accepted

Has there ever been a sideways H-tail on an airplane?

The double decker horizontal tail was a popular choice for large biplanes, even into the 1930s. Below is a picture of the Zeppelin Staaken R VI giant airplane and below it a Handley-Page H.P.42 ...
Peter Kämpf's user avatar
16 votes
Accepted

What is the function of this fixed protrusion on the tail?

That is almost certainly a navigation antenna. From the E190 AOM (Airplane Operations Manual): You can see the VOR2/LOC2 antenna rather more clearly in this photo: (The VOR1/LOC1 and VOR3 ...
Fiddlesticks's user avatar
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16 votes
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Why is the horizontal stabilizer root interface designed this way?

It is a seal- to prevent entry of air into the stabilizer mounting area. For aircraft with trimmable horizontal stabilizers (THS), there is an opening to the rear of the aft bulkhead to allow for the ...
aeroalias's user avatar
  • 100k
16 votes

Why are fighter jets equipped with dorsal fin?

There are two features that you may be referring to. A) Is an antenna that is shaped to provide low drag. Not all F16 have this. B) The true dorsal "fin": increases structural strength decreases ...
jwzumwalt's user avatar
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16 votes
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Why do the C-141 and C-5 have T-tails?

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 ...
Peter Kämpf's user avatar
16 votes
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How exactly do the Beechcraft 1900's stabilons work?

This Flight Safety Training Manual describes them as improving "deep stall" characteristics and C of G range. The stabilons are fixed surfaces that add effective stabilizer area to improve ...
John K's user avatar
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15 votes
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What is this little strake on Cessna 182 vertical tail?

It's one half of a VOR receiver antenna. There will be a corresponding element on the otherside of the tail. The complete unit looks like this: Source Disclaimer: I have no affiliation with the the ...
CatchAsCatchCan's user avatar
15 votes
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Why don't airliner vertical tails extend to the very aft of the fuselage?

The three main duties of a vertical (as well as horizontal) stabiliser are: to trim; to control; and to provide with stability the airplane. the root of the vertical tail doesn't extend right to the ...
sophit's user avatar
  • 13.8k
14 votes

Why are airplanes parked at the gate with max rudder deflection?

I have no experience on Boeing or Airbus airplanes but the most likely cause would be gust locks installed on the aircraft. Some aircraft, like a C-172, have a pin that locks the aileron and ...
wbeard52's user avatar
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13 votes
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How do tailless aircraft yaw?

Technically the B-2 bomber has rudders, they are "drag rudders" (or split rudder) and are located on the outer portion of the wing: Source: Quora The rudders open in a clamshell ...
Ron Beyer's user avatar
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12 votes
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What are these unsymmetrical parts at the tail of the Tupolev TU-144?

The four parts you're referring to contain the actuation mechanism for the rudder, similar to the wing pods that contain the flap actuation mechanism. The reason they are not arranged symmetrically ...
aeroalias's user avatar
  • 100k
12 votes

Why do T- tail airplanes have a shorter vertical stabilizer?

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 ...
rela's user avatar
  • 121
12 votes
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Why is the empennage design of this Lockheed 1049E so complicated?

Complicated is a matter of opinion and I wont address that specifically since its somewhat subjective. But the core of the question is "why did the L-1049E have 3 tails" which is a legitimate question ...
Dave's user avatar
  • 101k
11 votes

Why aren't there V-tail airliners?

Controllability and redundancy. Airliners are certified according CFR 14 Part 25, which specifies that upon engine fail the aircraft must still be able to fly and climb: it must have more than one ...
Koyovis's user avatar
  • 61.8k
11 votes

Why do the C-141 and C-5 have T-tails?

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 ...
Pilothead's user avatar
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9 votes
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Is there a formula to calculate how big a ventral fin should be?

There is no single formula - the number of factors to consider are too numerous and the load cases are too diverse. Here is an incomplete list: Directional stability: Depending on fuselage size and ...
Peter Kämpf's user avatar
8 votes

What are the benefits of a non-orthogonal (scissor) tail-rotor?

Image source The tail rotor of the Apache consists of two 2-bladed teetering rotors, referred to as scissor rotors. This unusual configuration was first implemented by Hughes Helicopters in the late ...
Koyovis's user avatar
  • 61.8k
8 votes

Has there ever been a sideways H-tail on an airplane?

There is quite a famous example of this! but other than the Wright Flyer, I don't know of any. My layman conjecture as to why this is not more common is that the tail only needs to be large enough ...
Daniel's user avatar
  • 588
8 votes
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What is the angle of attack of horizontal stabilizer?

You are right, the horizontal tail of a conventional airplane appears to have a higher incidence, but the actual angle of attack is smaller than that of the wing. The wing, flying ahead of the tail, ...
Peter Kämpf's user avatar
8 votes
Accepted

Why does operating the rudders in the engine slipstream offer improved rudder authority at low speed?

A propeller accelerates the air flowing through it in order to create thrust. This acceleration is highest at low speed. The acceleration will increase the dynamic pressure at the tail if it is in ...
Peter Kämpf's user avatar
8 votes

Why don't commercial aircraft use all-movable tail surfaces like my RC plane?

For a small RC plane that travels at slow speeds your design would work great. However these type of designs have structural limitations. For an all movable vertical and horizontal stabilizer setup ...
DLH's user avatar
  • 5,809

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