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# Tag Info

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Living Wing The Super Hornet has a living wing, that is to say, the shape of the wing is constantly in motion throughout every regime of flight. Trailing edge flaps, leading edge flaps, stabs, rudders, and ailerons all move in concert to give the pilot the greatest control during particular phases of flight. This is evident by the use of the flaps switch. ...

45

I flew for two 747 carriers that never bought new aircraft, and thus this answer applies to 747-100/200 aircraft as originally manufactured for a number of different airlines. The tiller is active when the aircraft is on the ground and the nose gear is compressed regardless of groundspeed as I remember. I've never heard of a pilot accidentally hitting it ...

39

This is called Split Rudder and it provides redundancy. They run on different systems so if one fails, the other one can be used. Here is a picture of a split rudder: Split rudders also provide a finer high speed control, in that only the lower one moves at high speed, reducing the exposed surface area and therefore the control effect. Very importantly, ...

37

From a totally practical standpoint, let's say you're in a small tricycle gear aircraft with a freely castoring nose wheel (or a tail dragger) and you're starting your takeoff roll in a calm wind. When you bring the power up, the aircraft is going to want to turn left (why is another question), in other words to yaw about its vertical axis in a counter-...

37

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 pipes, and the control surface is free to move. The rudder is moved from the center position by wind. If you observe the gates, you should note that all airplanes ...

31

All of the aircraft that I have ever seen have the rudder and braking functions combined into one set of two pedals. To operate the rudder you press on the bottom part of the pedals, so that they slide back and forth on tracks, and to operate the brakes, you press the top part of the pedals so that they rotate towards the floor. The left pedal operates the ...

25

The rudders are deflected inwards during takeoff of the F/A-18E to help in raising the nose of the aircraft as it leaves the ship. As the vertical fins are canted outwards, deflecting both the rudders inwards generates a downforce, which, due to its location aft of the center of gravity, creates a pitch-up moment. This position of rudders during takeoff is ...

25

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, a normal airplane will not fly at all. Only then it is a control surface, which allows it to fly well and how you want it. Consequently, the size of the tail ...

23

Short answer: Rudder and ailerons have different purposes and control rotation about two different axis, but their use is coordinated since a rotation about one axis induces a secondary rotation on the other one. The rudder use is mostly to prevent unwanted yaw movement for safety and comfort, or to force yaw against the aircraft tendency to keep the ...

23

There are many higher-order effects. For example, yaw causes a slight increase in airspeed over the outer wing of the turn and a decrease in airspeed over the inner wing. As a result, the outer wing will generate more lift than the other, introducing a rolling motion. Yaw also causes side-slip which triggers several effects. Wings that are swept backwards, ...

21

It works in a half-assed way but the key word is half-assed. You'll always be skidding around the sky since sideslip is required to obtain and maintain any rolling moment. Control response can be somewhat laggy, since you have to induce a skid and wait for the roll, depending on how much dihedral you have. So to have something approaching snappy control ...

20

Most transport aircraft use yaw damper systems to take care of minor rudder inputs. Most autopilot systems are actually only 2-axis - pitch and roll since the rudder's job is only to keep the tail lined up behind the nose. The yaw damper is a separate "autopilot" system and has limited authority, sufficient to deal with minor yaw disturbances, dampen dutch ...

18

To turn – any vehicle, not just an airplane – you need to generate corresponding centripetal force. When you only apply rudder, the plane will turn a bit, but because unlike boat it has no keel, it will not generate much centripetal force, just fly somewhat sideways, which is called a skid. It will produce more drag this way. Now any well designed plane ...

18

Instructors that teach that to students are fools. You should be using rudder only as required to keep the ball centered - period. If you are applying rudder to influence the pitch attitude, to "help hold the nose up", this is very very bad, and leads to stall/spin accidents. Rudder is mostly being used to counteract adverse yaw from the aileron inputs, ...

17

With a fully deflected rudder the airplane will fly with substantial sideslip, and by dropping the windward wing it can be held on a straight course. This is usually done intentionally with gliders and light aircraft when they want to lose altitude quickly, because the high sideslip angle will increase drag substantially. If $\zeta$ is your rudder deflection ...

16

The purpose of yawing is, as you note, to provide a way to rotate the airplane around a vertical axis. Ailerons can roll the airplane around a longitudinal axis and produce a slipping turn, and turning with the rudder alone produces a skidding turn, but proper turning is a combination of both aileron and rudder inputs and produces a coordinated turn. ...

15

When you deflect the ailerons, you increase lift on one side of the wing and decrease it on the other. This causes a parallel increase of the local induced drag where lift is increased and vice versa. The consequence of that is a yawing moment which needs to be corrected with rudder deflection. Once your ailerons are neutral, this yawing moment goes away, ...

14

Here are a few design constraints: Unlike a car, there is sometimes the need to apply the left brake independently from the right brake. (See What is differential braking? for more details and pictures.) There is a need to control the rudder, and you need to be able to move it either direction. The pilot needs to be able to make small and rapid adjustments ...

14

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 elevator in place. Other airplanes have an externally mounted device locking the rudder in place. http://www.weekendcfii.com/photos/c172preflt/C172_gust_lock.jpg ...

14

The vertical stabilizer is immobile (if it starts to move, you're in deep shit), and provides stability in yaw (it keeps the aircraft pointed more or less in the direction that it's moving). The rudder is mobile, and typically attached to the aft edge of the vertical stabilizer. It provides controllability in yaw (it allows the aircraft, if necessary, to ...

13

After stopping by at our physics friends, it's probably because of the swept wings (causing a lift differential) of the B737: [...] if you introduce a yaw to the aircraft, one wing will extend out more directly into the wind-stream, while the other wing will be even more swept. This effectively makes one wing longer, and the other wing shorter. [...] The ...

13

The reasons can be split in two categories: Direct and indirect. Direct reasons are rolling moments which are created directly due to the rudder deflection and the side force on the vertical tail: Offset position of the vertical tail: Since the rudder is above the longitudinal axis of inertia, a side force will also cause a rolling moment. This is the main ...

13

Depending on the manufacture of the aircraft (Boeing or Douglas) the use of the tiller or nose wheel steering is different. Douglas aircraft, like the DC-8 and DC-9, had limited nose wheel steering (15 deg) through the rudder peddles. These aircraft could be taxied to a limited turn radius with the rudder peddles as they were linked into the nose wheel ...

12

As pointed out by Farhan, it adds redundancy to the aircraft. A 747 once experienced a rudder hard over. Even with the split rudder design, the crew had to rely on asymmetrical thrust to control the aircraft. If it had one very large rudder surface, control would be much more difficult, or may even be impossible.

12

The key in flying a good roll is to keep the aircraft's nose up in anticipation of the lift requirement when flying in knife-edge or inverted flight. Since in knife-edge the elevator and rudder will assume each others function, you will need rudder as well as elevator for directional and pitch control. Also, depending on adverse yaw, some rudder is required ...

12

The short answer is that at negative 2 G, the airframe limit for the A7-E, it took little effort to keep your feet on the rudder pedals. In controlled flight there are aircraft limitations on both positive and negative G. I flew the A7-E for the US Navy and have some operational experience that might offer some context to the question. I believe the ...

11

Effect on Aerodynamic Coefficients It is possible to locate a vertical fin, as well as a control surface, ahead of the center of gravity. $c_{n_r}$ (yaw-induced yawing moment or yaw damping) will not likely change much, all other things being equal. $c_{n_\beta}$ (sideslip-induced yawing moment or directional stability), on the other hand, will be reduced, ...

11

The real reason: Ground effect was not considered during development. Ground effect reduces the lift curve slope of lifting surfaces, and the low tail position of the F-18 makes this effect very noticeable during take-off. During development, this effect was not considered and, consequently, the F-18 could not rotate at the calculated speed when it went ...

11

First and foremost you should always be looking at the turn coordinator to see what is going on and applying rudder as necessary. In your specific case (if we want to discuss the physics), basically what your instructor is saying is that you are using the ailerons to bank (turn) the plane and the rudder to counteract the propeller's yawing moment. The ...

11

It depends on the aspect ratio of the wing and the lift coefficient. Short, stubby wings at low angle of attack will not create much adverse yaw with aileron input, especially when the ailerons have differential linkage (more deflection on the trailing-edge-up side and less on the opposite side). Differential gearing is also beneficial in reducing stick ...

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