Have you ever wanted to fly? Where would you go if you could? Just imagine zipping through the air, while all of your friends are left to walk!
People can't fly on their own. But we've invented devices to help us fly. Let's take a look at some of the ways that human beings can and can't fly.
Birds are one of the few animals that can fly. Human beings have analyzed birds to help them invent flying devices. One reason birds can fly is the flat shape of the bird's wing. Air flows faster on the top of the wing and slower on the bottom, which provides lift. Also, birds flap their strong wings to lift their bodies up into the air.
Gravity on Earth weighs everything down. Birds have hollow bones and feathers. Their bodies are light. As a result, birds have an easier time pushing against gravity.
If birds can fly, why can't human beings fly? One reason is that gravity pulls us down to the ground. The weight of our bones and bodies holds us down on the ground. Another reason is our body shape. We do not have wings to lift us up into the sky like birds.
People have always wished they could fly. They have tried to invent special machines to fly. There are many inventions that allow us to take to the skies.
The most common way that people can soar above the clouds is to take flight on an airplane. But how can airplanes fly? Gravity pulls airplanes down. Airplanes need wings in order to create lift. Lift pushes against gravity. Air creates lift by flowing around the airplane's wings. The plane must gain speed to push the air around the wings. Propellers or jet engines also push or pull the plane forward. This is called thrust.
Rockets and jetpacks are other ways that people can fly. A rocket is an engine that can push itself forward and upward by producing thrust. People fly rockets into outer space and to the moon. A jetpack is a special device that allows a single person to go up into the air. The propulsion engine in a jetpack pushes the person wearing it upward.
A jetpack has three tanks. The first tank is filled with pressurized nitrogen. The second and third tanks hold hydrogen peroxide. The only problem is that most jetpack flights last just a short period of time.
Have you ever seen people flying in a hot air balloon? A hot air balloon is a giant cloth pocket filled with heated air or gases. When the gas is hot, it lifts the balloon. People fly by riding in a basket connected to the balloon.
People can also fly by using a hovercraft. This device hovers above the ground. A hovercraft has a rubberized skirt that surrounds the lower edge of the craft. The hovercraft is lifted up above the ground by air pushed through fans. It makes an air cushion that enables the hovercraft to go upward. People sometimes like to fly these craft over and around the water.
People have always wanted to fly, but never have been able to fly on their own. Birds have evolved to fly all over the world and soar through the sky by only using their wings.
Because of human ingenuity, we have so many amazing devices to help take us to the sky. Do you think someday someone will invent wings for humans to use? Who knows what the future holds! Until then, you'll have to book a trip on a hot air balloon or strap on a jetpack. Happy flying!