A long time ago, I thought it was impossible (in real life, of course) for skydivers to do anything but fall straight down before their parachutes opened. Since then, I’ve seen videos that have made me think otherwise. Formation skydiving, for example, where people maneuver to grab onto each other and form patterns with their bodies:
So, how do skydivers maneuver like that? Is it more or less intuitive or just the opposite? Do height, weight, etc. make a difference or is it pretty much the same for everyone?
The same way aircraft and birds maneuver, sailboats sail, kites fly, leaves flutter to the ground, etc.–a surface presented to a moving stream of air is moved about by that stream of air, moving differently depending on the shape and position of the surface. They move their body parts about to act as control surfaces.
Stick your hand out of the window of a moving car. Change the position of your hand. Feel the force of the wind pushing your hand. That’s how skydivers maneuver.
Yeah, you have quite a bit of maneuverability at lower altitudes even just with body form and with a wingsuit you can get a lot of glide and a lot of control.
At higher altitudes where military parachutists do High Altitude Low Opening (HALO) and High Altitude High Opening (HAHO) jumps, however, you have to be careful to not develop too much spin or tumble because the diver doesn’t have enough aerodynamic affect to counteract it, and can actually pass out because of the body forces and their effect on circulation.
Think of a badminton birdie, it will fall straight down. But if you could manipulate the feathering, change the center of gravity relative to the drag, you could make it rotate, slide to one side or the other, relative to another birdie, etc. A skydiver in a stable arch position has their center of gravity around their navel, and their arms and legs giving a balanced drag, they’re falling straight down. Bend your heels to your butt, and stick your arms out the other way, and you’ll slide sideways in the direction of your knees. Stick your legs out stiffly and bring your hands to your shoulders and you’ll slide the other direction. Twist your torso so that an imaginary plane of your upper body and hands is 45 deg to the air and you’ll rotate like a windmill. It’s a hoot, I highly recommend it.
I’ve done this. There is probably a place nearby where you can try. You can get instructions and feel how it is to try to stay stable in the air. I absolutely recommend it.
Me too. You don’t get a lot of time in the wind tunnel for your money, but I was able to experiment just a bit with an instructor standing next to me and ready to grab me if (welll, when) things got out of control. In the standard belly-down freefall posture, I was able to yaw left and right by rotating my palms to deflect air left or right, but that was about as much control as I was able to exhibit in the few minutes I had. I couldn’t easily control fore-and-aft movement, and I also tended to develop an unstable fore-and-aft rocking action, prompting the instructor to reach out and steady me from time to time. I think with maybe 20-30 minutes of practice I could have achieved a stable freefall in the tunnel. To achieve the kind of maneuvering capability seen in the video shared by @3AxisCtrl takes, uh, a bit longer.
Before indoor skydiving, people had to learn this stuff by jumping out of airplanes - which meant you got about thirty seconds of experience at a time. And from what I’ve seen, it was common to have two handlers with you during your learning dives to ensure you didn’t go completely out of control before it was time to pop your chute. In other words, learning to freefall was expensive as hell, and also time-consuming. two freefall handlers, a plane, a pilot, a chute repacker, and all the time associated with getting up to jump altitude (and the chute glide after your freefall). I’m guessing thirty seconds of freefall instruction probably took 30-45 minutes out of your day and a couple hundred bucks.
Thanks to those who tried to answer my question, especially to @outlierrn and @Machine_Elf for providing some details. I hadn’t thought about some of those things, like bending limbs selectively or cupping hands.
That looks like Lake Powell near Antelope Island to me. It’s a common filming location, and where Charleton Heston and his doppelgänger James Franciscus kept crashing into every time they went to the Planet of the Apes because apparently NASA could send spacecraft to other star systems but not manage to land them safely.
