The Engineering Design Process ... With My 5 Year Old Daughter (Pt. Two)
The first part in this blog series covered my daughter's thought process as we established some basic requirements for our rocket. After we settled on these initial requirements it was time to start designing and eventually testing! Naturally, the design process in our case is much simpler (and faster) than would be in reality, but it is important for her to understand how important this step is! We will come back to the design step over and over as we test.
Step Three: Design
Since I have been working remotely, the power of the whiteboard is one of the things I absolutely miss the most. Last Saturday we pulled out the trusty whiteboard and wiped off the dust and had a short actual whiteboarding session together. We worked on designing the rocket and briefly talked through some of the materials we would use. We drew a rocket based on pictures we saw and talked about how we could build it. My daughter recognized that we needed something strong enough to hold the water (we talked about using water as rocket fuel in our first prototype). She also recognized we needed something to push the water out, just like fire is pushed out of a real rocket to make it fly. She recognized the top of the rocket should be somewhat aerodynamic (I explained why that would help it fly). She also recognized the rocket should have "tails" or fins, although understanding the aerodynamics of those was a bit beyond our scope :)
Step Four: Build It!
Now that we had a basic design, we needed to source the materials and build it! Ultimately, after talking about materials we decided to start with cheap and available materials. The main fuel tank would be a standard small soda bottle. We will use a small cork to plug the bottle and fill it half full with water. Then we built some "fairings" to wrap the bottle out of yellow construction paper. These fairings helped give us that typical rocket shape. Finally, we added some fins from triangle shaped cuts of cardboard (we used a toilet paper roll for this).
Step Four: Test It!
Now that we built our first prototype rocket, it was time to test it! We started with a "static fire test" ... basically we tested the air pressure would pop out the cork without adding any "fuel" to the bottle. The test worked well!
After initial testing it was time to fill the rocket and test it for real! We setup a basic "launch pad" from a couple pieces of scrap 2x2s and connected the tire pump! After a brief countdown ....
Catastrophe! The look of disappointment on her face haunts me, but it is critical (more on that in a moment). We did try one other launch configuration with the rocket at an angle and with less water to see if it would go further in an arc trajectory. After that second launch, she recovered the rocket in pretty bad shape and it was the end of our tests.
Step Four: Redesign and Improve
Now we have come to the most critical lesson of this entire project, understanding and handling failure. This is by far the most important thing my daughter can learn from building a rocket ... If you are trying, you will fail at most things you do. It is very important to learn early on that failure is not the end but rather is an opportunity to learn. It is a necessary and guaranteed step in the journey no matter what she pursues in life, and she will be judged (mostly by herself) not by failures but by how she responds to them.
Clearly, our first rocket failed to achieve any of our requirements. After revisiting our requirements with her, we concluded our first rocket did not fly really high, it was not reusable and it certainly could not have protected an egg. Building a rocket is not easy and success is not guaranteed but we know we can do better! We identified that we need more power, stronger "fairings" and a more stable launch surface! Now it's back to design!
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