Rockets are are cool, right? What if you could build a rocket that does not fly high in the sky, like most rockets, but in circles at high velocities? Well I did, and its called the rocket propelled centrifuge. The rocket propelled centrifuge is a device that uses model rocket engines to accelerate in circles at high velocities. It even has a sensor to measure the RPM of the device so you can find the velocity and acceleration. The rocket propelled centrifuge will make an awesome weekend project or physics class demonstration. This instructable will show you how to build the centrifuge and the sensor. The video below will give a breathtaking slow motion view of the centrifuge in action (Starting at 2:15).
Lets get started!
Step 1: Tools and Materials
For this centrifuge, you need to acquire a few materials and tools.
The materials you will need are:
- 1/2 inch PVC Pipe
- Ring stand
- Ring stand clamps
- Balsa wood
- 50G Weights
- Rocket engine
- Model rocket engine holder
- Type B modle rocket engine
- 10K resistor
- Reed Switch
- Arduino Uno
- Computer & USB cable
- Duct tape
- Model rocket fuse and igniter
- Small Metal Rod
The tools you will need are:
- Hot glue gun
- Soldering Iron
Step 2: Assembling the Base
To assemble the rocket centrifuge base, you will need to take the ring stand, and cover it with rocks. Make sure they are heavy rocks so the centrifuge will not fall over. Then, use clamps to secure the smaller metal rod to the ring stand rod. The base should now be done.
Step 3: The Rotor
After the base has been built, it is time to build the rotor. To do this, you will start by drilling a hole in a piece of PVC pipe. Drill this hole in the end of the pipe and make it the size of the the smaller metal rod sticking up from the top of the base. You will then need to use duct tape and hot glue to secure a balsa wood rod to the side to the PVC pipe in the opposite direction of the PVC pipe. You can then slide the pipe on top of the small metal rod and secure it with a ring stand clamp.
Step 4: Adding the Rocket Mount
To add the rocket motor to the rotor, you will need to find the base of a model rocket. This is a cardboard tube that will hold the rocket motor. You can then attach this to the PVC pipe using duct tape and hot glue. It should be secured in place so it does not change angle while moving.
Step 5: Balancing the Rotor
After the rocket motor has been added to the PVC pipe side of the rotor, it will be imbalanced. One side will be heavier. To fix this, glue and tape weights to the balsa wood side of the rotor until it is balanced. The rotor should be able to spin freely now. This step makes the centrifuge spin faster and not wobble.
Step 6: Adding the Sensor
The sensor will measure the time it takes for the rotor to make one 360 degree rotation. To do this, a reed switch and magnet will be used. The sensor will be built on a piece of broken paint stick. to make the sensor, take a magnetic reed switch, and solder a 10k resistor to one side. Then, connect the resistor side of the sensor to arduino ground, the reed switch end to 5 volts, and the middle of the circuit to pin eight. You can then glue the soldered setup to the paint stick. Once the glue dries, use a ring stand clamp to attach the sensor to the ring stand. After that, use hot glue to attach a magnet to the rotor directly above the sensor. Below the sensor, attach the arduino to the ring stand using a clamp.
Step 7: Coding the Data Logger
For recording the data produced by my centrifuge, my laptop is set near the centrifuge and connected to the arduino. The code records the time, in 10 milliseconds, when the sensor is triggered since the start of the code. The data is then saved to the serial monitor. The data can then be copied into a spreadsheet to be calculated.
Step 8: Setting Up the Rocket
To set up the rocket igniter, add a fuse and plug into the rocket motor, and connect the fuse to the wires coming from the rocket igniter box.
Step 9: The Launch!
To launch the rocket propelled centrifuge, make sure all your cameras are running. Then, just press the button on the igniter box, and watch the show! You should watch the video in the intro to see the cool results. The centrifuge will then spin in a circle very fast. Make sure to stand back just in case the centrifuge flies apart!
It should look really cool.
Step 10: Making Sense of the Data
The above data graphs are the tangential velocity of the rotor at every turn. I calculated this by dividing the circumference of motion by the time it took to make the full rotation. As you can see, the rotor reached a maximum velocity of 25m/s. Overall, this experiment was a success and produced a very cool result.
Thanks for reading and remember to vote for me in the contests!
Good luck building!
Disclaimer: This project deals with flammable materials and high velocity objects, use caution when building and testing.