Building experimental STEM project rocket, by Kausthub P, 10th grade
In this project let’s see if we can use powdered sugar, potassium nitrate and Bentonite clay, to make a homemade version, that will rocket up over 2,000 feet high, and cost less than Rs.1000 to make. To begin with we’ll need powdered sugar, potassium nitrate, and bentonite clay. We’re also going to need 3/4” PVC tubing and a 3/4” oak dowel. This is schedule 40 PVC, and I’ve cut the tube into sections 5” long. The dowel is twice as long as that. This will be a ramming dowel, and a template as well. Let’s get ready to make the rocket fuel, and to start we’re going to need a small blender to make the fine potassium powder.
The first thing we have to do is measure out 65 grams of potassium nitrate. Now powdered sugar, we’re going to need some of that next. So let’s zero out our scale, and add 35 grams of sugar to the mix. At this point, the powder is a pyrotechnic composition that could ignite with too much heat, so instead of mixing this up with the blender, we’re going to have to shake it by hand for about 3 minutes. This should give it enough time to blend completely, and that’s important because we need this white mix to be as homogenous as possible.
Ok, we’ve got everything we need, so let’s get to work putting it all together. Place one of the PVC casings on a slab of concrete, and drop in a third of a tablespoon of bentonite clay. Now let’s make sure we keep the tube firmly on the concrete so the clay doesn’t spill out the bottom, then slide the oak dowel inside, and hit the top firmly with a rubber mallet. It’s going to need about 5-8 good whacks, to compact it as tight as we need it. And you can see it will make a nice little clay plug, at the bottom of the tube. Let’s repeat this process 2 more times until the plug is 3/4” thick, which you can see is conveniently indicated by the marking on the stick. At this point, we’re ready to add the white mix. This stuff is extremely light and fluffy, so it’s important to push the ramrod down, very slowly. Once it’s compacted by hand though, we can ram it with the mallet, just like we did the clay, until the rammed “white mix” lines up perfectly with the next marking. The last step for this simple motor is a bentonite clay end cap. This will be 3/4” thick as well, the same as the one we made before. Ok, our rocket motor is just about finished.
The only thing left to do is make the nozzle. For these motors, I use a 7/32” drill bit, which happens to be the exact length and width we need to turn this rammed powder tube, into a core burning rocket. Now to gauge the depth of how far into the drill, we can use the markings on the ramrod to measure exactly where the white mix ends, then mark the drill bit at the point where it lines up with the clay. Now it’s really important to drill this out very slowly and carefully because, remember, this is a rocket motor, and you don’t want to set it off by accident. I’m drilling mine out by hand, so it’s easy to control any heat generated, from the friction. When the marking on the bit lines up with the bottom of the casing, the rocket engine is finished.
As I lived in a place covered by trees and properties I couldn’t launch the rocket up Vertically as it would be potentially hazardous. So to overcome that I have changed the purpose of the rocket engine to not power a rocket but a grounded car. To build the car I used a spare wooden plank, screwed furniture wheels so that it cannot steer and clamped the rocket engine to one end of the plank. I used a sparkler fuse to ignite the solid fuel core.
Overall it was a very fun and interesting project that helped me understand the chemistry and dynamics of a solid core rocket engine.