# Terminal Velocity in Skydiving

Sep 21, 2022

## Terminal Velocity in Skydiving

Ah, science! You probably learned about this stuff in high school, but you never learned it like this.

Remember ‘terminal velocity‘ from physics? Your high-school self might have dropped a ball bearing into oil, taken some readings and scratched down an equation or two. You’d have learned (yawningly) that the terminal velocity of a falling body occurs when the force exerted on it by gravity is exactly balanced by the force exerted on it by resistance, such that the body experiences zero acceleration. Well–that’s a ball in oil. This is skydiving.

### What is the Terminal Velocity of a Skydiver?

The downward speed achievable by the human form in freefall is a function of several factors–including the body’s mass, orientation, skin area, and surface texture–but the usual math standardizes all that. For a human-shaped object, the equation spits out a terminal velocity of 60 meters per second–about the terminal velocity of the typical skydiver, which clocks in at of 55 meters per second.

It ain’t that simple, though, as you might imagine.

### Terminal Velocity of a Belly to Earth Skydiver

Skydiving doesn’t just revolve around tandem jumping. It doesn’t even revolve around the type of skydiving–called Relative Work, or “RW”–that involves falling with your belly pointing toward the Earth, as the above equation assumes. Since different skydives result in different air resistance, they end up resulting in what can be very different terminal velocities. For instance: In a stable, belly-to-earth position, a jumper’s terminal velocity hangs out at a zippy 120 mph.

### Terminal Velocity of a Head Down Skydiver

Change that body position to head-down, and you’ve just ramped up that terminal velocity to around 150-180 mph. It is fast enough to result in damage to both parachute and skydiver if that skydiver doesn’t do him/herself a favor and slow the heck down by changing position and waiting before pulling. There are ways to minimize that drag even further by streamlining the body, which allows for speeds in the vicinity of, ya know, 300 mph.

Here are a couple of examples of skydiving disciplines on the opposite ends of terminal velocity. These will do much to show-and-tell about how this can be the case.

### Terminal Velocity in Speed Skydiving

Speed skydiving is a skydiving discipline that has supported competition divisions since the mid-2000s. It’s a big enough deal that it has its own association–the International Speed Skydiving Association. It has the goal to “achieve and maintain the highest possible terminal velocity.” Speed skydiving is the fastest non-motorized sport on Earth.

The tricks of the speed skydiving trade have been developed to cheat nature as much as possible. Obviously, the skydiver cannot increase his or her mass enough to significantly increase his or her terminal velocity. Additionally, the skydiver can’t change his or her shape much beyond the use of an aerodynamic helmet. In fact, the primary tool in a speed skydiver’s kit is the reduction of friction–that “surface texture” point in paragraph number two. To that end, competitive speed skydivers often prefer to wear slick bodysuits and skillfully maintain a strictly streamlined head-down body position to minimize the coefficient of drag. They have to do all of that lickety-split after exit, too, in order to hit that maximum speed high enough up that the air is extra-thin. It’s a challenging discipline, and well worth checking out!

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### Terminal Velocity in Wingsuit Flying

Wingsuit flying aims to translate as much of the downward speed of a skydive into forward speed. Terminal velocity drops precipitously so that the throttle forward can roll way the heck back.

To that end, wingsuit pilots (as indeed, pilots they very much are) integrate ram-air airfoils into their suits. They pressurize in similar ways as a parachute and fly using many of the same dynamics as an airplane. While some of these designs have three distinct ram-air wings (which connect the arms to the torso and the legs together) and some are mono-wing (which turns the whole suit into one large wing with a human kinda floating around in the middle somewhere), the overview of the design is the same: A wingsuit combines various materials in order to construct an airfoil around the frame of the human body, converting downward speed to forward.

As the discipline of wingsuit flying has advanced, the results have been nothing short of incredible. One instance shows a vertical velocity of a scant 25 mph–100 miles an hour less than the average 125 mph. However, the speed at which the wingsuit pilot pierces forward through the sky zooms over 100 km/h in some instances. This doesn’t really qualify in anyone’s book as slow…just not so downward.

Interested in feeling what 120 miles per hour of terminal velocity feels like? Hop down to Skydive California, and we’ll be happy to show you!

## What Does Terminal Velocity Mean In Skydiving?

When people talk about tandem skydiving and jumping out of an airplane, one number they’ll often mention is 120mph. Is this true? The answer is. kind of.

Terminal velocity means the top speed an object can achieve when it falls through the air. While gravity is a constant force, terminal velocity is not – it is created and affected by a few different things.

The weight and density of an object speed it up. The shape of the object, and the drag it creates as it falls, slows it down. And the combined result is the object’s terminal velocity.

How this works in tandem skydiving is that people equip themselves correctly and train to manipulate their body position so they can go at the same speed. Skydiving on your own is great, especially at Skydive OC but getting together with you friends in freefall is even better.

Smaller skydivers wear tight fitting suits to create less drag, or even wear extra weight to add speed. Larger skydivers wear baggy suits and fly their bodies in positions to create more drag and go slower. This is where the number 120 mph is used, as it is considered the approximate average terminal velocity of a skydiver.

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#### Getting There

When you jump out of a skydiving plane, terminal velocity isn’t immediately achieved – it takes a little time. At the instant you first jump out you are actually thrown forward on the same trajectory as the plane (that is going forwards at around 100mph). Over the course of the next 10 seconds, this forward momentum is overtaken by the effect of gravity as you travel on a big graceful arc into freefall. This is referred to in skydiving as “going down the hill” as it visualizes a curve.

#### Orientations

Skydivers do things in different ways, and depending on this it affects their average terminal velocity. While flying face-down, jumpers indeed have an average terminal velocity of 120 mph, but if they are ‘freeflying’ – which means adapting your body position to fly in other orientations such as ‘head-up’ and ‘head-down’ – the average terminal velocity is more like 160mph. Speed skydiving is where people point their head directly at the ground and streamline their body as much as possible in an attempt to go as fast as they can, which can reach over 370mph!

#### Records!

The current record holder of both the highest jump and fastest freefall speed is Alan Eustace. In 2014 Eustace jumped from a big balloon at 123,414ft and broke the sound barrier on the way down with a top speed of 822mph. He achieved this speed falling on his belly to remain stable, and was able to do so because the higher up you go the thinner the air gets creating less drag.

#### Feelings

So terminal velocity is not a single set speed and can be affected by various factors. The speed 120 mph is what you hear most because it is kind of true and is a nice round number that people have a frame of reference for.

The really important thing to understand about jumping from an aircraft and falling towards the earth at terminal velocity is how it feels. There is something particularly exciting about the skydiving sensation of speed created from gravity alone that separates it from other experiences where you go fast for thrills. When you do jump it just feels right, and is the most natural and freeing sensation – like your whole life has been building up to this moment. What are you waiting for? Join us for a jump and find out for yourself!

## Terminal Velocity in Skydiving

Ah, the study of the physics of skydiving: the practicum of which presents the world’s most bombastic science field trip. On paper, calculating the terminal velocity in skydiving looks kinda like this:

How fast does a skydiver – who clocks in at X total weight – fall at X landing altitude in X weather conditions when he/she adopts X body position?

As you can see, it’s a titch more complicated than the “120 miles per hour!” the internet usually offers when you ask how fast you fall when you’re skydiving. If it’s a surprise that you actually get a choice – lean in.

#### 1. Want a simple answer? Design a simple situation.

Terminal velocity physics — as with most things scientific — gets simpler when fewer variables are involved. That, indeed, is where the internet got its reductionist approach: from the fact that most tandem pairs are comparable enough in size, and adopt a comparable enough body position once they’ve hit their airborne stride, to be more-or-less comparable at large. That’s why it’s a commonly thrown-around figure that the average terminal velocity for skydiving hangs out at about 120 miles per hour. It’s a solid average for a related group, and it’s a nice, clean number.

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Another reason 120mph is significant that you can test it for yourself – if you can find a big enough fan: 120 miles per hour is also the precise wind speed at which a standing person loses the ability to stay upright and in one place. (Check out XKCD for the visual on that.)

#### 2. Terminal velocity in the sky, on a cloudless day, doesn’t feel as fast as terminal velocity does when you pass a cloud.

Ready to check the way terminal velocity physics works in real life versus how terminal velocity physics works in the context of your imagination? Book two tandem skydives: One, on a day with a few clouds floating around, and the other on a day that’s totally bluebird. This’ll kinda blow your mind.

Try to make your first jump on a cloudless day. Sure, you’ll be as full of butterflies as a bag of rotting fruit in the middle of the Amazon, but you’ll certainly be able to remember at least one thing about your experience: that you don’t feel like you’re hurtling down at 120 mph. Unimpeded by visual references, with the world spread out like a map beneath you, you’ll hear the wind, but you won’t feel like a dog with its head out the window on a Nascar track.

If you’re lucky enough to pick a day for your second jump that offers a couple of puffies for perspective, you’ll be very surprised. When you pass a cloud on the way down, your true speed is revealed. (And boy howdy is that fun.)

#### 3. Skydiving terminal velocity can change depending on the shape you make.

Once you’re a sport skydiver, you have some choices when it comes to terminal velocity on any given skydive. The shape you make — whether that’s the shape you show up in, or the acrobatic maneuvers you perform, or the kind of suit you wear — factors in heavily.

Heaviness, indeed, is a thing: Heavier folks fall faster. Jumpers in baggier clothing fall slower, because of the extra drag. Body position is a much bigger deal; the more surface area you present to the wind, the slower you go. (Speed skydivers try to point the crown of their head directly at the ground. That kind of skydive is over a little too fast for our taste, but they make for some pretty amazing records.)

Got more questions? Don’t be shy! We’re happy to answer them for you. Just ask!

Source https://skydivecalifornia.com/blog/terminal-velocity-skydiving/