Engineering Captain America’s Shield

“That thing does not obey the laws of physics at all!”

Maybe to you, Spider-Man, but who says we can’t follow the laws of physics and still become superheroes? YouTuber Jake Laser turned himself into a real Avenger without gamma radiation or Super-Soldier serum, and all he needed was some physics and spray paint.

How Does Captain America’s Shield Work?

Laser set out to engineer a real Captain America shield that bounces off of walls. In the movies, Captain America’s shield is made of Vibranium, a fictional metal that takes in kinetic energy. Vibranium is also in Black Panther’s suit:

Rather than spend millions to create a new metal, Laser wanted to find a material close to Vibranium, or at least find a way to emulate it.

The main challenge with this: strength. Not bulletproof strength, but elastic strength. Laser speculated that when Cap throws his shield in the movies, all the potential energy (an object’s latent, stored energy in relation to its surroundings) returns to the shield and turns back into kinetic energy (an object’s energy from motion), which causes it to bounce off objects and boomerang back to the thrower. 

Elastic Deformation

This reaction is similar to what makes a rubber bouncy ball bounce. When a bouncy ball hits the floor, the impact creates kinetic energy, and the ball stores this kinetic energy as potential energy due to elastic deformation. 

You may not see it, but when the ball hits the ground, it deforms and squishes down, but because of its high elastic limit it can snap back. This turns the potential energy back to kinetic energy and causes the ball to bounce back toward the thrower:

So if Laser builds a circular piece of equipment with a high elastic limit, it will bounce off of walls and work just like Cap’s shield, right? One problem: Bouncy balls don’t fly, at least not smoothly or for long distances. Next stop: the Frisbee. 

How Does Captain America’s Shield Fly?

Cap’s shield flies like a Frisbee or a wing: The slow air on the bottom creates high air pressure and lifts it up as it moves through the air. Frisbees can also fly smoothly thanks to the gyroscopic force from their rotation: 

Creating and Testing the Shield

Laser had his plan set. He needed an object with:

A bouncy ball’s bounce (a material with a high elastic limit)

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A frisbee’s flight (An object that creates high air pressure underneath itself for flight and rotates for stabilization)

For the bouncy material, Laser chose fiberglass since it’s lightweight and has a high elastic limit. He started with a small, fiberglass ring with plastic in the middle…and…success! The small ring easily bounced off walls and back into his hand, but this new toy wasn’t nearly as big as Cap’s shield.

When Laser tried a larger version of this design, it failed because of the weight. A thinner ring, perhaps? Success again!

Deflecting Objects

But Captain America can’t walk around with a plastic shield! Laser would have to find a center for the shield strong enough to deflect objects, but not so heavy that the shield can’t bounce or fly. Carbon fiber? Almost, but when the shield flies and hits the wall the vibrations from the impact throw off the flight. He would need to isolate the carbon fiber from the rubber ring…

What about some kind of shock absorber? He put latex rubber around the ring to reduce vibrations from the impact. Although it couldn’t withstand bullets and shrapnel, the shield deflected small objects like glass bottles, and with a magnetic wrist strap for easy release and catch, Captain America 2021 was complete!

The Lesson

Lesson learned: You don’t need a super metal or radiation to be heroic; you just need basic science.