Man flying jetpack at the 1967 Superbowl. Photo: Vic Stein/NFL/Getty Images
Jetpacks are awesome, so I’m going to write about jetpacks. Lots of us grew up thinking that someday people would be zooming about in the skies attached to small rockets. Freedom from our earthbound existence is attractive for a number of reasons, including applications for first responders, law enforcement, military, structural engineering and simply how awesome it would be. Before we strap in to infinity and beyond, we’ll talk about three things: How do jetpacks work? What are the jetpacks of today capable of? Why should we maybe not have personal jetpacks?
The physics behind jetpacks are pretty simple. These rely on the conservation of momentum or that says that for every action there is an equal and opposite reaction. Jetpacks (a lot like rockets) will spit out fuel, water, or air in one direction sending you off in the other direction. Fuel particles are very small and light, so they have to be sent out very fast to make up for the comparatively large weight of a human. The speed of tiny particles is another way of thinking about heat (higher temperature air has faster moving molecules than lower temperature air), so the exhaust of the jetpack is likely very hot.
Today’s jetpacks boast some impressive numbers. Some jetpacks are capable of flying nearly 10,000 feet (3050 meters) in the air at speeds of over 100 miles per hour (160kmph) using turbojets. Unfortunately the constraints on fuel mean that it is only operable for about 10 minutes at a time. Other designs run on gasoline with an effective range of about 10 miles (16 kilometers) with 28 minutes of flight time. These options are great, but if you’re concerned about your carbon footprint and still want the weightless flight experience there are aquatic variants. These, in somewhat cartoon fashion, strap you to a pair of giant firehoses that propels you about 30 feet (10 meters) into the sky.
Jetpack demo by Apollo Energy Gum in Denver, Colorado Photo: Jet Pack International
A big limitation on jetpacks come from the constraints of burning fuel. Jetpacks suffer the same problems as rockets in that they have to carry their heavy fuel with them. Making the jetpack heavier means more thrust is required to move it, requiring even more fuel. Fuel is heavy making the problem worse over again. Burning all this fuel will also unfortunately impact the environment and contribute to global warming unless we implement nuclear power in some way. However, as this Guardian op-ed points out, people are likely not going to enjoy being strapped to small nuclear reactors (no matter how cool Iron Man makes it look). Speaking of Iron Man, he showed us just how dangerous it can be when something goes wrong while flying miles above the surface.
Jetpacks are out there and it might not be too long before we begin to see them doing rescue or regulatory work. If you have deep pockets you can buy your very own jetpack and fly around for a few minutes which should be just long enough to impress your friends or an Olympics opening ceremony. The rest of us earthlings must look forward to high speed rail and autonomous vehicles to get us from place to place. I hate heights, so that’s fine by me.
Bryan Visser (Vice-President & Editor in Cheif)
Bryan is a 3rd year graduate student studying DNA replication. He hopes to make a career in science advocacy, science journalism or science policy. In his free time, Bryan enjoys board games and ballroom dancing.
scienceaces.wordpress.com 