Comment by sandworm101
2 years ago
>> tumble and essentially not make any lift
Tumbling itself can produce lift. The difference in drag between one side and the other can result in net pressure differences for a moving object. This is the basis of many baseball pitches. Spin a brick fast enough and it might just be able to climb if thrown horizontally.
If static airfoils are complicated, try looking into airfoils that rotate or otherwise move in relation to airflows. A Russian engineer once said that all problems in aerospace are placed on the tip of every helicopter blade.
The Magnus effect is super confusing to think about. Basically, to provide lift, the brick or ball or whatever would need to be "rolling" backards, like a wheel. In baseball, e.g. fastballs are usually thrown in such a way as to "roll" backwards, which causes them to climb. Curveballs are accomplished via topspin. Sinkers roll forward. You can even tune this behavior by making the surface of inconsistently "sticky" to the air, so flow of air is more or less affected by the objects rotation. This is why licking the baseball is against the rules.
Curiously, the rotation can also lend the ball's path greater stability against changing air currents/densities and crosswinds. Knuckleballs are famously hard to throw because they have very little spin, but they are also notoriously hard to hit because the trajectory is so subject to the vagaries of airflow between pitcher and batter.
This is to say nothing about when the axis of rotation is predominantly parallel to the direction of travel (e.g. rifle bullets and American footballs), where the Magnus effect effects the rotating objects ability to continue to rotate parallel to the direction of travel. Get it right and the spin makes the path more stable, but get it wrong, it becomes less stable. The hows and whys of that are beyond my understanding of fluid dynamics, but its fun to think about how complicated it can get.
edit: got my spin directions confused