Why do plane and helicopter pilots have to pysically fight with their control stick when flying and something goes wrong?
In: Engineering
As others have said, that’s largely theatrics in movies and TV.
There are essentially three systems in use:
* Fly-by-wire is what you will predominantly see in modern airliners and military aircraft. Here, your stick isn’t actually physically linked to any control surface – instead, your inputs send signals to a computer which then positions flight control surfaces to do what you are asking the computer to do. The computers are, in relaxed stability aircraft (like fighter jets), actually continuously sending signals to the flight controls to keep the jet flying stable. In some aircraft, if you turn off the flight control computers entirely, your jet is no longer able to maintain controlled flight.
In this case, the fighting control stick does absolutely nothing. In fact, you won’t even feel the actual feedback from flight control surfaces on aircraft because the stick isn’t directly linked to them.
* Hydromechanical. This is used in older fighter jets and in airliners/aircraft with big control surfaces. Basically, when flying at faster speeds (which creates larger pressure/air loads on control surfaces), human power isn’t enough so the control stick is *mechanically* linked to hydraulic systems that move the control surfaces for you. These hydraulic circuits operate in the thousands of psi. For instance, if you pull the stick back, you are mechanically telling the servos and actuators to move the stabilator (or elevators) to pitch the aircraft up.
In this case, if you did have something go wrong, fighting the stick doesn’t do much either. Most likely, if something went wrong, it’s because your hydraulic line or mechanical linkage broke, or you lost a control surface. In which case, fighting the controls won’t do you anything.
* Direct linkage. This is what you commonly see in older aircraft/lighter aircraft/general aviation like in your Cessna. Here your control surfaces are directly linked to your control stick/rudder via wires and pulleys. You will directly feel the loads on the control surfaces.
Here is where you could, like in the movies, perhaps try to fight for control via physically fighting the stick more. A jammed linkage or connection might require more force to fight through. But even then, you risk breaking something even worse (sudden snapping of control surfaces can overwhelm mechanical limits) OR getting into a PIO (pilot induced oscillation).
MORE likely to happen is if you have a failure in a control surface (e.g. an aileron fails), you have to put in some input like rudder or opposite aileron to keep the plane flying straight and level. In that case, you are “fighting the controls” by keeping some force on the stick to maintain the flight attitude you want. But you aren’t “fighting the stick” like in the movies – instead, you’re precisely and finely putting your control inputs in (or trimming the aircraft) to offset what was lost.
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