# Why does my paper airplane with the ailerons configured to make it spin fly straighter than with them configured for straight flight?

I made a paper airplane with a standard design, except I cut out the back ~2 cm of the body, leaving ailerons on the wings. If I throw it with the ailerons straight, it doesn't fly very far and turns to one side. If I point one aileron up and the other down, so it spins, it flies straighter and farther. Why? I've seen this effect with two planes of this design.

(Not sure paper airplanes are on topic here, or if the question would be better on Drones SE, but there's a tag here but not there.)

• Seems on-topic to me @Someone. I think you'll need to edit with some pictures to get a good answer.
– GdD
Oct 20, 2022 at 8:39
• Please attach a picture of your paper airplane. Oct 20, 2022 at 21:13
• @TypeIA is exactly correct. based on your clarification what you are seeing is spin stabilization. Or put another way, you are seeing first-hand the benefit of spin stabilization. If there is an imperfection in wing symmetry, the plane will tend to yaw left or right and keep right on yawing in a curved path. But when the plane is spinning, that yaw never "accumulates" in one direction, rather you fly in a corkscrew motion around a center line. Oct 21, 2022 at 3:23
• @TypeIA would you please post that as an answer? Oct 21, 2022 at 3:25
• @Someone I've posted an answer, I hope it helps! Thanks for the updates to the question and the photos and have fun with your exploration of aerodynamics. Well done. Oct 21, 2022 at 7:17

You're witnessing the effects of spin stabilization. It's the same phenomenon that makes rifle bullets fly farther and straighter and why American football players try to throw a spiral.

Your paper airplane has some dynamic instability: there's a positive feedback loop where a small disturbance causes an aerodynamic force that further increases the disturbance. The plane quickly goes out of control and crashes. By introducing rotation, the direction of the force is continuously varied so that the positive feedback loop is broken: the effect of the force summed through a complete rotation cancels out. You get a wobble, but thanks to the rotation it isn't allowed to develop into a full loss of control.

Spin stabilization is also used for spacecraft, but for a different reason: to give the object angular momentum which will dominate over disruptive effects of thermal radiation, gravitational gradients and other nuances of orbital mechanics, allowing one of the orientation axes (the spin axis) to stay more or less fixed. With your paper airplane, the angular momentum isn't very important, but the cancellation of disturbing forces by summing them around a full circle of rotation is.

• Oh - I always thought spin stabilization was just about gyroscopic effect, but it seems not to be so. Oct 21, 2022 at 7:29

I've experienced something similar with paper airplanes that I have built. I would attribute it to imperfections in the construction of the plane - folds not perfectly straight, angles of wings to fuselage not exactly the same, etc. Therefore, bending the ailerons to a degree which would normally produce a turn simply corrects for the imperfections in the construction of the paper plane. Just a guess.

• I would think that, but it's spinning throughout the entire flight, and it flies straight with the ailerons in either direction (left up/right down or vice versa). Oct 20, 2022 at 20:32
• When you say spinning are you referring to it continuously rolling along the longitudinal axis? Oct 20, 2022 at 21:53
• Yes, rotating along the longitudinal access. Basically the same motion as a propellor on a real plane. Oct 20, 2022 at 22:02