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I'M ALL ABOUT Falcon and the Winter Soldier—the latest Marvel show on Disney+. Don't worry, I'm not going to spoil anything serious. I just want to talk about the wingsuits in episode 1. Sam Wilson (Falcon) is dealing with a hostage situation aboard a military aircraft. The bad guys grab their hostage and jump out of the plane wearing wingsuits. If you haven't seen these, they are basically skydiving outfits with extra material between the arms and legs to make it like wings—thus the name.

The hostage doesn't have a wingsuit, so they strap him on the back of one of the bad guy jumpers. After that, Falcon flies in pursuit and there is some action stuff—see, no real spoilers

But really, this is just a chance to talk about some fun physics. So, let's consider the following two questions. One: How fast can a human fly with a wingsuit? Two: What would happen if you have an extra human (a hostage) on the back of a wingsuit jumper?

Free Fall

Let's start with something simple and then make it more complicated. (That's what we like to do in physics.) Suppose you jumped out of a plane and there wasn't any atmosphere. Yes, that would be super weird—but just imagine. For this case, there would just be one force acting on you—the downward-pulling gravitational force due to the interaction between you and the Earth. The gravitational force can be calculated as the product of your mass (in kilograms) and the gravitational field (we use g for this). As long as you are within about 100 kilometers of the surface of the Earth, the gravitational field is about 9.8 newtons per kilogram.

What does this constant downward gravitational force do in an airless world? That's where Newton's second law comes in. It gives the following relationship between force and acceleration:

Two important notes. First, both forces and accelerations are vectors. (That's why they have an arrow over them.) This means that both the magnitude and direction matters. Second, this expression deals with the net force (the total force). Since there's only the gravitational force, you would accelerate downward—your speed would just keep increasing for as long as you fall. But that's just pure falling and not wingsuit flying.

Let's add another force to a falling person—the air drag. This is a force in the opposite direction as the motion of the object. It's a result of air molecules colliding with the surface as something moves through the air. Suppose that I replace the air with large balls instead—oh, and these balls are just completely stationary before the interaction with a falling object. As the object moves down, there is a collision, and then the balls move off with different (but mostly downward) velocities. Here is a diagram to help you see this:

Flying (Falling with Style)

If you take that falling wingsuit and tilt it just a little bit, something cool happens. The collision between the air and the suit pushes the air down and to the side.

Since the air balls (or you can just call it air, if you like) are deflected to the right, the drag force on the falling object is somewhat to the left. With this left-pushing force, the falling object will increase its horizontal velocity. So, now it will be falling down and moving to the left. That's better than just plain falling.

Of course, now there is another problem. Since the object is moving to the left, it will also collide with air balls on the left side. This makes the force situation a little bit more complicated. It's actually easier to split this air drag force into two parts. For the part that is in the opposite direction as the velocity of the object, we will call this the drag force (like before). However, the rest of the interaction with the air must be perpendicular to the drag force—and we call this lift. Yes, drag and lift are two parts of the same interaction.