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Defying Gravity

This teen athlete uses physics to perform amazing aerial feats

April 2022
By Jennifer Barone

Michael Ross Cunningham

EJ Carr

Wind rushes past Sydney Kennett as she spins and twists in the air. The 15-year-old is a competitive skydiver, but she’s never jumped out of a plane. Instead, she takes flight indoors with the help of a specialized tunnel designed to mimic skydiving—no parachute required.

Sydney, who lives in Colorado, is one of the world’s top athletes in the fast-growing sport of indoor skydiving, also known as bodyflight. Competitors perform stunts inside a wind tunnel, a big tube with fans that create powerful jets of air. Sydney first flew in a wind tunnel at age 4. Her dad, Andrew—an outdoor skydiver—wanted to share his love of flying. Although her memory of that first experience is a little hazy, her next one, at age 8, was unforgettable. “I had the time of my life,” she says.

Wind rushes past Sydney Kennett as she spins and twists in the air. The 15-year-old is a competitive skydiver—but she’s never jumped out of a plane. Instead, she does all of her aerial stunts indoors. She uses a specialized tunnel designed to mimic skydiving—no parachute required.

Sydney lives in Colorado. She’s one of the world’s top athletes in indoor skydiving, also known as bodyflight. This unique sport is becoming increasingly popular. Competitors perform stunts inside a wind tunnel—a big tube with powerful fans that blow air upwards to keep athletes aloft.

Sydney first flew in a wind tunnel at age 4. Her dad, Andrew—an outdoor skydiver—wanted to share his love of flying. Sydney doesn’t remember that first experience very well. But her next one, at age 8, was unforgettable: “I had the time of my life,” she says. Soon after, Sydney joined an after-school indoor skydiving program. She started participating in competitions not long after that.

Indoor Skydiver Sydney Kennett
Watch a video about Sydney Kennett's competitive indoor skydiving.

Shortly after that flight, Sydney joined an after-school indoor skydiving program and started participating in competitions. In her main event, called freestyle, athletes complete a few required moves during an artistic routine they’ve choreographed. Judges assess the routine’s difficulty and how well the athlete executes it. In her first world championship, at age 12, Sydney earned a bronze medal in junior freestyle. More recently, she set a Guinness World Record for the most spins (68!) while doing a split in a wind tunnel in one minute.

Flying in the tunnel “feels kind of like you’re in The Matrix,” says Sydney. In the sci-fi movie, characters in a computer simulation bend the laws of physics to perform fantastic feats. In the tunnel, “I let go of all my worries and just fly,” she says.

The main event Sydney competes in is called “freestyle.” Athletes complete a few required moves during an artistic routine they’ve choreographed. Judges rate the routine’s difficulty and how well the athlete executes it. In her first world championship, at age 12, Sydney earned a bronze medal in her age group!

More recently, Sydney set a Guinness World Record for the most spins while doing a split in a wind tunnel in one minute. She completed a dizzying 68! Flying in the tunnel “feels kind of like you’re in The Matrix,” a movie where characters bend the laws of physics, says Sydney. In the tunnel, she adds, “I let go of all my worries and just fly.”

Up in the Air
Watch a video about the writer's experience trying indoor skydiving for the first time.

The Terminal Velocity Formula

When Sydney is in the wind tunnel, she’s falling at terminal velocity. This speed depends on the person’s mass and drag, which varies with body shape, posture, and suit type.

VARIABLES:

m  =  mass, in kilograms (kg), of the person or object falling

Af  =  area, in cubic meters (m3), facing the direction of the wind

Cd  =  drag coefficient, a unitless value based on the shape of the person or object falling

V  =  terminal velocity, the final speed a person or object falls at, in meters per second (m/s)


The Terminal Velocity Formula

When Sydney is in the wind tunnel, she’s falling at terminal velocity. This speed depends on the person’s mass and drag, which varies with body shape, posture, and suit type.

VARIABLES:

m  =  mass, in kilograms (kg), of the person or object falling

Af  =  area, in cubic meters (m3), facing the direction of the wind

Cd  =  drag coefficient, a unitless value based on the shape of the person or object falling

V  =  terminal velocity, the final speed a person or object falls at, in meters per second (m/s)

VARIABLES:

m  =  mass, in kilograms (kg), of the person or object falling

Af  =  area, in cubic meters (m3), facing the direction of the wind

Cd  =  drag coefficient, a unitless value based on the shape of the person or object falling

V  =  terminal velocity, the final speed a person or object falls at, in meters per second (m/s)

USING A FORMULA

The formula for terminal velocity (above) shows the relationship between the speed, mass, drag, and area of an object in free fall.

EXAMPLE

When Sydney flies in the air tunnel on her side, her drag coefficient is 1.2, her side area is 0.24 m2, and her mass is 38.5 kg. What’s her terminal velocity?

STEP 1

Replace the variables in the terminal velocity formula with the values you know.

STEP 2

Isolate the unknown variable, if needed, and solve.

STEP 3

V = 46.72739 . . .  ≈ 46.73 m/s

So Sydney’s terminal velocity when flying in the air tunnel on her side is 46.73 m/s.

USING A FORMULA

The formula for terminal velocity (above) shows the relationship between the speed, mass, drag, and area of an object in free fall.

EXAMPLE

When Sydney flies in the air tunnel on her side, her drag coefficient is 1.2, her side area is 0.24 m2, and her mass is 38.5 kg. What’s her terminal velocity?

STEP 1

Replace the variables in the terminal velocity formula with the values you know.

STEP 2

Isolate the unknown variable, if needed, and solve.

STEP 3

V = 46.72739 . . .  ≈ 46.73 m/s

So Sydney’s terminal velocity when flying in the air tunnel on her side is 46.73 m/s.

Use this information to find the missing variables in the formula. Round answers to the nearest hundredth. Record your work and answers on our answer sheet.

Use this information to find the missing variables in the formula. Round answers to the nearest hundredth. Record your work and answers on our answer sheet.

When she first gets into the wind tunnel, Sydney flies on her stomach. The area of her body facing the wind is 0.5 m2, she has a drag coefficient of 2, and her mass is 38.5 kg. What‘s her terminal velocity?

When she first gets into the wind tunnel, Sydney flies on her stomach. The area of her body facing the wind is 0.5 m2, she has a drag coefficient of 2, and her mass is 38.5 kg. What‘s her terminal velocity?

Sydney then changes her body position. Her drag coefficient is now 0.5, and the area of her body facing the wind is 0.4 m2. What‘s her new terminal velocity?

Sydney then changes her body position. Her drag coefficient is now 0.5, and the area of her body facing the wind is 0.4 m2. What‘s her new terminal velocity?

When curled into a ball, Sydney’s terminal velocity is 65 m/s . The area of her body facing the wind is 0.3 m2. What’s her drag coefficient?

When curled into a ball, Sydney’s terminal velocity is 65 m/s . The area of her body facing the wind is 0.3 m2. What’s her drag coefficient?

A. Another competitor has a mass of 42.5 kg. His drag coefficient is 2 and his terminal velocity is 25 m/s when he first gets into the wind tunnel and is flying on his stomach. What’s the area of his body facing the wind?

A. Another competitor has a mass of 42.5 kg. His drag coefficient is 2 and his terminal velocity is 25 m/s when he first gets into the wind tunnel and is flying on his stomach. What’s the area of his body facing the wind?

B.  Would you expect his terminal velocity to be greater than or less than Sydney’s when in the other positions? Explain on a separate sheet of paper.

B.  Would you expect his terminal velocity to be greater than or less than Sydney’s when in the other positions? Explain on a separate sheet of paper.

Continue the Learning Journey

  • Write a short paragraph explaining why you would or would not want to try indoor skydiving.
  • Redo questions 1 through 3 from the article using your own mass to solve for the missing variable. Be sure to convert your weight to kilograms before solving!
  • Practice using another real-world formula, °F = 9/5°C + 32 and °C = 5/9°F – 32, to convert temperatures from Celsius to Fahrenheit and vice versa. Use the formulas to convert the following temperatures: -3°C, 75°F, 200°C, -46°F.

Continue the Learning Journey

  • Write a short paragraph explaining why you would or would not want to try indoor skydiving.
  • Redo questions 1 through 3 from the article using your own mass to solve for the missing variable. Be sure to convert your weight to kilograms before solving!
  • Practice using another real-world formula, °F = 9/5°C + 32 and °C = 5/9°F – 32, to convert temperatures from Celsius to Fahrenheit and vice versa. Use the formulas to convert the following temperatures: -3°C, 75°F, 200°C, -46°F.
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