Rechargeable batteries and capacitors are similar in that they both store electrical energy. But there are major differences in how they’re constructed, and how they charge and discharge. Batteries store energy chemically, and have a higher energy density but relatively slow discharge rate. Capacitors store energy in electrical fields, have a low energy density, and discharge very quickly. Supercapacitors add an insulator that increases storage density, but decreases discharge speed. In his newest video, YouTuber Tom Stanton used supercapacitors to launch a small model rocket.
Normal model rockets, like what you may have built as a kid, use small combustible hobby rocket motors for thrust. Stanton thought it would be interesting to build an electric version that gets its thrust from a propeller. Using supercapacitors instead of normal rechargeable batteries offered two major advantages. First, the can be recharged very quickly, so the time between launches is minimal. Second, the fast discharge rate means that the propeller motor immediately receives the maximum amount of torque, making the acceleration very high.
To test those concepts, Stanton 3D-printed the body of the rocket. It has a pretty standard shape, with the exception being the nose where the propeller is mounted. The nose contains the propeller, motor, ESC (Electronic Speed Control) and RC receiver, and the supercapacitors themselves. After assembly, Stanton took the supercapacitor-powered rocket out to a field for testing. The results were surprisingly good, and the rocket was able to reach pretty impressive heights by the time the supercapacitors were drained. The parachute would then deploy, the rocket could be retrieved, the supercapacitors quickly recharged, and Stanton could launch again!
Tom Stanton Builds a Supercapacitor-Powered Model Rocket was originally published in Hackster Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.