I’ll try... There are three motions observable on an airplane, pitch, roll and yaw. All of these are controlled by the pilot to make the aircraft perform the desired movement and all of these forces have aerodynamic surfaces that can be moved to achieve the desired result. They all work the same way by moving a surface against the airflow to deflect the lifting surface (wing) in such a way to influence lift.
The so-called tail of the aircraft does not carry any of the weight of the aircraft, its purpose is to influence the pitch, or the angle of attack of the wing, which does carry all the weight. The rudder is there to control yaw and only in certain circumstances (landing in a crosswind, for example) is it actively used, in flight the computer operates it automatically, calling it a “yaw damper.”
Pitch, the one we are discussing, is controlled by the elevator whose motion is controlled electrically, hydraulically or by cables by the pilot pulling or pushing on his control column. Most modern aircraft have hydraulically actuated rams which are controlled electrically through the assistance of a computer. The amount of force required to deflect a large surface like an elevator against the airflow is high, hence the hydraulics (or “boosted controls”).
If you can picture the forces required to deflect these surfaces and think of how long they might need to stay in the same relative deflection, for example a climb or descent, devices called “trims” are installed to help the pilot. For example, If a climb from take-off to cruise elevation is desired, the pilot pulls on the column and without a trim, holds that back pressure. And holds it and holds it, using the force to deflect the elevator. As you might imagine, this is fatiguing and difficult to be smooth for the hour or so that this might take so for passenger and pilot comfort, trim systems are added. As the main control is deflected, the pilot can move a trim, either mechanically through a wheel and cables or electrically. In the case of a modern aircraft, the entire horizontal stabilizer can be adjusted into the airflow electrically by moving a jackscrew that moves the horizontal, “ not moving” surface. This effectively takes the force off of the pilot’s column and keeps it centred, taking the strain off the pilot so he can relax and the aircraft keeps the same climbing attitude with the control column neutral.
In practice, the pitch trim is continuously being moved. The rudder trim, however, is usually set once and forgotten, the yaw damper (part of the autopilot) controls the rudder. Same with the aileron trim, it is set so that the aircraft returns to wings-level when the column is released after a turn and is rarely adjusted.
The trim is a powerful tool and on those aircraft that use them, small surfaces attached to the trailing edge of the elevator can be moved against the airflow to deflect the elevator. This is the method most small or older aircraft use although a Cessna 185 trims its horizontal stabilizer with a jackscrew...On some older larger aircraft, like a DC6b, the elevator was not connected to the pilot’s control wheel at all, it was free-floating and trailed in the airstream. The pilot’s control wheel was attached directly to the trim surface which moved and deflected the elevator to control pitch. I found that difficult to comprehend when I first encountered it, but it works fine.
Most well-designed aircraft, particularly those that carry passengers, are stable. That means they fly neutrally with little input from the pilot, tending to just cruise like a car on the freeway. Any deflection from stable flight means the aircraft returns naturally to stable flight condition. Conversely, a fighter is designed to have little or no stability, its ability to maneuver depends upon it. If a gust hit a fighter and the pilot did nothing, it would not return to stable flight on its own. Events like winds, power changes, flap deflection or landing gear movement up or down can affect stability such that aircraft have to compensate for these changes and usually a control deflection of some sort, perhaps accompanied by trim is required. In most cases, the autopilot does all this. Modern aircraft are almost exclusively flown by the autopilot and/or a computer except the final stages of landing, ground maneuvers and takeoff. Passenger comfort demands this.
Sometimes these automatic systems (or any other systems) fail which is, in modern times, the primary purpose of the crew still being up there (and to get the aircraft to the terminal, still done manually). Because aircraft are very complex now, pilots go back to school every 6 months to get more training and to re-qualify. In addition, authorities require that you have to do a minimum of 6 take-offs and landings before you qualify to fly the aircraft each 6 months.
In North America and Europe, pilots had a long apprenticeship in small aircraft before they were qualified for larger airlines; it was a process of flying larger and more complicated aircraft and progression was slow and many pilots might not get to be an airline captain until the later half of their careers. This meant that captains had huge experience and were very well trained in multiple aircraft types. When things went wrong, pilots like Sulley used their vast experience because there was no direct specific training to save the day. Recurrent training is designed to expose the pilots to all of the emergencies he might face, or have been faced, by other pilots.
Nowadays, low-cost airlines, airline failures and many start-ups, low wages coupled with difficult working conditions means that fewer people are willing to be pilots - there is a current world-wide shortage and many captains got to their positions without the long apprenticeship programs. A captain by age 28 was unprecedented in my day. New pilots must be excellent systems managers and most are but many do not have the fundamental flying skills, that old “stick and rudder” stuff to fall back on. Add long flying legs with the autopilot engaged and one landing at the destination and there is very little hand flying done. I have trained new pilots who were amazing on the computers, much faster than I would ever be, but few, if any, knew what the rudder was for.
Times change.
Sorry, this is obviously redundant, took too long to write and I was undercut. Good work guys!
