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Suppose that a plane lost the ability to use all the control surfaces on the wings (e.g., flaps and ailerons). Can the weight inside the plane be shifted to help maneuver the aircraft?

For example, moving passengers side-to-side in order to turn, or between the front and back to climb or descend.

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As explained in the other answer, most aircraft are too stable for sideways shifts in CG to induce a useful roll. That answer does a great job answering the question in your text.

However, your title question seems more general. Most hang gliders are entirely controlled by shifting the CG. So it is possible to entirely control an aircraft by CG shifts.

I also recall a report of a pilot of one of the Horton flying wing gliders (with very little sweep -- a 'flying plank') was able to loop the aircraft by nodding their head forward and aft.

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  • $\begingroup$ There are also ultralight powered aircraft that manoeuvre this way as well; in some areas, they're called "microlight aircraft". $\endgroup$
    – nick012000
    Apr 14, 2023 at 23:34
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Assuming you mean no roll control at all, lateral weight shifting has an effect too mild to be able to achieve useable control.

However, most airplanes can be controlled in roll by yawing them, depending on how strong the design's dihedral effect and roll/yaw coupling is.

For example, high wing Cessnas that have geometric wing dihedral along with the T wing placement can get decent roll rates going just by skidding. I used to tow gliders in a Cessna L-19 and I could control the plane reasonably well just with trim for pitch, and rudder for roll, without touching the stick at all, and I could probably land it in one piece, or at least walk away from the result, using trim and rudder only, if the runway was long enough.

Swept wing jets have very strong dihedral effect from the wing sweep itself (so much that anhedral is required if the wing is on top, to reduce total dihedral effect). If you lose all aileron control in a swept wing jet you can get very high roll rates going with small amounts of rudder-induced skid. As long as the yaw damper is still working so you don't have to struggle against dutch roll tendency, you could maneuver a jet around with mild rudder inputs to skid it to roll it into a bank, if you were very careful, if you had no aileron control (I used to experiment with that in the CRJ simulator, just for fun).

Landing a jet on rudder alone, well I'd try it if I had no choice, but I'd probably crash it.

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  • $\begingroup$ could putting all the passengers on one side turn the plane? +1 $\endgroup$ Mar 4, 2023 at 18:59
  • $\begingroup$ Yes you'd get a very mild roll (there are lateral Center of Gravity limits related to trim authority), but you'd have to order them all back and forth and the roll rates you get aren't enough to achieve anything more than very gentle maneuvers. The rates you get with gentle skids is WAY more. That's what I meant by "too mild to be able to achieve useable control". $\endgroup$
    – John K
    Mar 4, 2023 at 20:07
  • $\begingroup$ In early swept wing jets, when at high AOA, (as in landing), we only used the rudder/sideslip to roll. Aileron input would create adverse yaw, opposite roll and loss of control, (google "Sabre Dance" to see the result). Until they added leading edge slats to the F-4E, we only used the rudder when landing. $\endgroup$ Apr 14, 2023 at 17:22
  • $\begingroup$ Was there a tendency to excite dutch roll? The CRJs are stable in dutch roll mode when flaps are extended and you could control it with rudder even with yaw dampers off. It sounds like the F-86 was like that. $\endgroup$
    – John K
    Apr 14, 2023 at 20:38

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