We’ve probably all made matchstick rockets as kids. And around here anything that even vaguely looks like a rocket will get some imaginary flight time. But [austiwawa] is making some really cool 3D printed rockets that use common CO2 cartridges as a propellant. You can see them in action in the video below.
You might think just sticking a CO2 cylinder in a 3D printed jacket isn’t such a big deal, but [austiwawa] really went the extra mile. He read up on how to make the rocket stable (by manipulating the center of gravity versus the center of pressure) and explains what he had to do to get the rockets flying like you’d expect.
In addition, the launch tube is pretty interesting. A 3D printed part holds a sharp point and a spring. You lock the spring and when released it punches a clean hole in the propellant casing. The actual tube is a long piece of PVC pipe. From the video, it looks like these little rockets fly pretty high.
Judging from the video, the rocket body and launcher came from TinkerCAD. The way [austiwawa] put the fins on was both simple and clever.
Of course, you could also use Coke and propane, if you like. We’ve also seen some pretty cool setups with compressed air. Check out the rockets in action after the break,
Over the years bicycle design has changed. Materials were upgraded as technology advanced, and accumulated knowledge helped bicycle builders make improvements along the way. But deep analysis with the intent to make meaningful improvements has not been widely embraced. Reasearchers at UC Davis are looking to expand into this frontier by letting the bicycle tell us how it can be improved. This is one of the test bikes they’ve been working on, which is mainly aimed at data harvesting. They’re hoping to find some real improvements based mostly on how the machine can get out of the rider’s way as much as possible. The thought here is that the rider’s body makes up 80-90% of the volume of the vehicle and should be accommodated in every way possible.
Sure, this could be a case of trying to build a better mouse trap. But listening to the discussion in the video after the break really drives home the complex issues of stability and locomotion that go into these seemingly simple vehicles. We’re going to guess the final recommendations will not involve making the bike five times taller.
It might not be as elegant or technologically-advanced as a Segway or a motorized unicycle, but this easily constructed 2-wheeled robot might be a fun project for a free afternoon. The heart of the balancing mechanism is an SPDT switch with a button cell attached that reverses the motor when the robot begins to tip in one direction. It’s not controllable and it tends to fall over quite a bit, but it’s a good starting point and could be refined by lowering the center of gravity or figuring out a simple way to change the motor speed based on how far the robot has tipped over. There are no accelerometers or tilt switches so the components could be sourced from a parts bin, and its simple design definitely leaves a lot of room for improvement.