With the little that I've learnt about aeroplanes, I know that the aileron is the control surface that a pilot use to roll the plane by decreasing the lift of one wing and increasing the lift of the other wing. And it's (aileron) generally located at the wing trailing edge.

Now, if the wing tip is made flexible (or hinged to the wing), can the wing tip serve the purpose of an aileron by lifting the wing tip upward or downward?

I have this shabby image for pictorial description

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    $\begingroup$ Tip: take-a-screenshot.org/windows.html $\endgroup$ – ymb1 Jan 11 '20 at 22:08
  • $\begingroup$ If it is hinged people would still call it an aileron $\endgroup$ – slebetman Jan 12 '20 at 2:53
  • $\begingroup$ @ymb1 Tip noted. $\endgroup$ – dammy999 Jan 12 '20 at 3:28

Yes, that will work. If the entire wing tip pivots, it simply acts as an aileron that takes up the entire chord of the wing.

Other alternatives to ailerons include:

  • Weight shifting. If you can shift the aircraft's center of mass left and right a significant amount, thus will cause the aircraft to roll in the same direction. This is how hang gliders turn.
  • Wing warping. Essentially the same thing as ailerons, but accomplished by bending or warping the wing rather than by pivoting a hinged piece of the wing. Early Wright aircraft did this, but I don't know of any modern aircraft that do. (Birds probably do this, too.)
  • Roll spoilers. By deploying a spoiler on just one wing, you'll cause the aircraft to roll in the same direction. Some airliners do this some of the time.
  • Sliding the wings left and right. Okay, I admit that I don't actually know of any aircraft whatsoever that do this. But if you were to slide an aircraft's wings left or right, that would cause it to roll in the opposite direction.
  • Cyclic pitch control. Only rotary-wing aircraft (such as helicopters) can do this. The rotor blades can be configured to change pitch depending on where they are in the cycle, and this can produce a roll. Cyclic pitch control is the main way that helicopters are controlled.
  • Yawing and using the dihedral effect. An aircraft doesn't actually need any roll controls at all if the wings have a significant dihedral angle. Instead, you can roll the aircraft by yawing it into a sideslip; the dihedral effect responds to the sideslip by rolling the aircraft. A lot of RC aircraft use this method, as does at least one ultralight aircraft, but it's not a great way to go, because sideslips produce drag, and they can produce a "snap roll" in the event of a stall.
  • $\begingroup$ Wow! What a great answer. $\endgroup$ – dammy999 Jan 11 '20 at 19:30
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    $\begingroup$ The MU-2 is totally reliant on spoilers for roll control, BTW. (it's part of why it requires special training -- normal techniques for stall/spin recovery don't apply as a result of this) $\endgroup$ – UnrecognizedFallingObject Jan 11 '20 at 19:56
  • $\begingroup$ @UnrecognizedFallingObject I've been thinking about the resulting stall/spin characteristics of an aeroplane that uses this wingtip device for rolling instead of the conventional aileron. Will the stall/spin handling procedures be identical to other planes that use aileron? Should I ask this in a separate question? $\endgroup$ – dammy999 Jan 11 '20 at 20:08
  • $\begingroup$ Roll spoilers and dihedral effect are also used in airliners as a backup for ailerons. $\endgroup$ – Jan Hudec Jan 11 '20 at 22:04
  • $\begingroup$ Roll spoilers also don't create adverse yaw, which is advantage for flying wings that have limited options for compensating it. $\endgroup$ – Jan Hudec Jan 11 '20 at 22:05

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