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An aircraft with side-by-side seating but only one person aboard should fly banked. Banking decreases lift and more elevator is needed than in leveled flight which increases drag. Correcting the banking with ailerons and rudder also increase drag. Which is better for economy?

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You might be better off correcting weight imbalance with more fuel in the opposite wing if possible. Then fly with fuel selector on both as long as you can. This should give you better economy than trimming aerodynamicly.

Notice this also true for weight too far forward or aft. Good balance helps in the air.

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Based on your question, you are correct: It will take more fuel to fly at a constant angle of bank.

If your goal is to remain at a constant altitude for as long as possible it would be better to fly straight and level, properly trimmed with the ball centered, than to orbit in a circle at a constant angle of bank with the additional elevator trim required to maintain altitude.

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You are really describing a banking tendency no? If the airplane is banked, it will turn. To make it fly with bank, without turning, you have to use opposite rudder, creating a sideslip, which you would never do.

So if you have a banking tendency, that is the airplane wants to roll in a certain direction all the time, is the banking tendency happening while the airplane is flying straight (ball centered) or is the banking tendency because the airplane is skidding (ball offset).

If you center the ball with rudder, so the tail is lined up behind the nose, and the airplane still wants to bank if you let go of the ailerons, you have either an unequal lift problem (something in the wings is not symmetrical) or a lateral weight distribution problem.

The options are to hold aileron input, with the ailerons displaced from neutral, to counteract the rolling tendency, or counteract the rolling tendency with lateral weight offset that results in the airplane flying level with ball centered with no aileron displacement.

From an efficiency standpoint, you want to avoid flying with controls displaced into the airstream, so it's more efficient to use weight offset to counteract a rolling tendency if offset is able to achieve wings level without displacing the ailerons. On a lot of airplanes you can achieve this with lateral fuel differentials when it's possible to feed from one tank or the other. You can create a deliberate fuel imbalance that counteracts the rolling tendency, then maintain this imbalance by switching back and forth as fuel is burned. I do this in my plane because it is quite sensitive to lateral balance.

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  • $\begingroup$ The original question was how to balance a single occupant‘s rolling moment in a light aircraft (i.e. lateral imbalance), if I understood correctly. $\endgroup$ – Cpt Reynolds Jan 5 at 21:07
  • $\begingroup$ Yes, that was exactly my original question. Leveling the slight banking needs only a slight touch in stick that can be tolerated but the constant left rudder (without a rudder trim) is inconvenient for the pilot. So I wondered how uneconomical is it to fly slightly banked and control the direction only with stick. $\endgroup$ – Tapio Pirilä Jan 6 at 16:42
  • $\begingroup$ Well the answer is buried in my blah blah blah. Don't use rudder to stop a rolling/turning tendency if the rudder application sends the skid ball off center. Only use rudder to center the ball. If it wants to bank with the ball centered, either hold the aileron in or shift fuel to make it go away. Otherwise you are flying along cockeyed. $\endgroup$ – John K Jan 6 at 17:13
  • $\begingroup$ You did not answer my question. The ball will be centered with aileron and rudder. But the question is economy: is it significantly uneconomical to fly slightly banked, elevator trimmed, direction controlled with stick and.. of course.. the ball slightly on the left due to banking. Forget the fuel. $\endgroup$ – Tapio Pirilä Jan 6 at 18:14
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If I understand your question, it is that having a single occupant aboard offsets the CG from the longitudinal axis of the aircraft causing a slight roll of the aircraft until the CG again aligns itself along the longitudinal axis.

This is, at least technically correct. However in most aircraft design features such as pendulum effect, preset trim tabs and dihedral angle of the wings largely diminish this to the point of being imperceptible to the pilot. You won’t even notice a difference flying solo as opposed to an even number of passengers aboard.

Whatever effects associated with this are nothing compared to the effects of overbwnking tendencies, left turning tendancies eg P-Factor, torque, spiral slipstream and propeller gyroscopic precession, thrust asymmetry from an inoperative engine(s), etc. these maladies are usually corrected by means of trim on larger aircraft or dampened out by flight control computers.

So yes, to be sure, the asymmetric loading from a single pilot does try to roll the aircraft slightly, which has to be countered with a roll torque opposing it which has additional aerodynamic consequences associated with it. It it’s so minor and countered by inherent design features for positive static and dynamic stability that you won’t even notice the difference in flight.

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  • $\begingroup$ With single pilot the lateral weight imbalance induces slight banking, so slight that turning tendency is minimal and almost unnoticable. But if I correct the banking with ailerons, I also need slightly but constantly to use the left rudder which is inconvenient in a long flight without a rudder trim. So my question, is the extra effort to make her fly wings leveled reasonable for economical point of view or do I let her fly slightly banked which is more convenient for the pilot. (Of course the best option would be to balance the plane). $\endgroup$ – Tapio Pirilä Jan 5 at 15:40
  • $\begingroup$ Yesterday I made an unofficial experiment with my ski plane. If the slight banking due to solo flying was corrected with aileron and rudder, the ground speed seemed repeatedly to decrease 1-2 knots compared to letting the plane fly banked, half the ball on the left, keeping the altitude with stick -- and so apparently with better economy. $\endgroup$ – Tapio Pirilä Jan 8 at 10:01
  • $\begingroup$ Interesting experiment, thanks for sharing! I remember from multi engine training that it is similarly more efficient to fly with the ball just a little out of center, but I can't remember the justification well enough to repeat it. I'm sure it has the same basis. $\endgroup$ – Michael Hall Jan 11 at 1:47

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