BTW, all lift based flying objects have an L/D ratio (which depends mainly on the airspeed), this includes birds, fighter jets, commercial airliners; and the discrepancies can be pretty interesting. For example if one looks at the L/D of the Concorde vs a subsonic jet it becomes clear why it was so damn expensive to operate. Or why the U-2 looks like a glider :). I cannot find any aerodynamic performance data on any famous long endurance (>24h) unmanned drone, but I bet it's rather high as well.
Another good example is the space shuttle. It does actually glide back down. But it glides like a brick at first (1:1 during its initial braking into the atmosphere), and then like a less dense brick (2:1 while it's still supersonic), and then like a brick with shitty wings (a whopping 4:1 or whatever on final approach). Which is about what the Concorde is during landing, 4:1, yea.
Pretty crazy stuff
(Obviously the space shuttle was a tradeoff for, you know, getting it into orbit via rocket)
A brick’s L/D is much worse than 1:1. I’m seeing people say 1:10 online, but I can’t find a source and I think that’s incredibly high. A real brick is going to tumble and essentially not make any lift.
A less dense brick will have the same L/D. L/D is about the shape, not the mass.
Neither lift nor drag has anything to do with mass. They are entirely determined by the surface of the object, and are not affected at all by the interior properties, including density.
Something a bit misleading done generally is aircraft don’t have one L/D, they have many, depending on angle of attack. When you see one number, it’s usually the best one.
I thought the point was that aerodynamics change from one domain to the next as shockwaves cause flow separation or eddies on or behind surfaces.
This is not the explanation you are looking for, but "aha the heavier object takes the same path but drops faster" was what made me okay with L/D not depending on weight.
I mean it looks like a brick and it flies
“Steerable brick in an atmosphere”… or the slightly more accurate “orientable brick in an atmospheric reentry regime”…
Kinda like a single control plane missile that spins (rolling airframe?), except... without the control plane lol.
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.
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