I've seen all sorts of Water Bottle Rockets on Instructables and while surfing the web but I thought an Instructable with the step-by-step process of building a whole bunch of them with a class of grade six kids would be good. Each step in the Instructable will be a day in the class. At the top of each day you'll find a list of tools and materials. Just follow through a day in advance and you'll have kids learning so much more than anyone bargained for.
This rocket is based on the usual 2 liter pop bottle you find at grocery stores. You add water, pressurized air and using these instructions you'll get height that you and your students will not believe. AND to make it interesting... we have a passenger... the Eggstronaut, which is an egg that if survives will award extra marks to the team.
You'll need the basic materials listed below as well as a launcher... Here's a link to a commercial version... i've added a couple of pics of it below as well.
I will design and build a launcher and do an instructable in a few weeks when I get a chance. I have seen all sorts of designs but I'm hoping to come up with something as effective as the commercial one above....
A good hand pump works well but a compressor REALLY makes life easy... you can max the pressure like crazy, too.
-The students will learn and apply Newtons Second Law of Motion in a way that makes sense to them...
"The more massive an object is... the more force it takes to accelerate it" or you could say...
"Heavy stuff takes more force to move"
-The students will learn and apply the basic principles of Newtons Third Law of Motion...
"To every action there is an equal and opposite reaction" or you could say...
"if you push something it will push back"
-The students will understand Newtons First Law of Motion...
"F=MA" or to make it so I can understand...
"stuff that is sitting there will stay that way unless something happens to it. Once things start moving they tend to keep moving until something happens to change how it is moving"
-Students will learn to tell the difference between MASS and SIZE
-By building a simple Rocket the students will understand these laws in a way that makes sense to them AND they will learn to think creatively, design and problem solve while building a basic design.
-The students will learn to use basic tools to construct a working project.
Tools and Materials:
-Hot glue gun
-X-Acto or Olfa mat knife
-2 liter pop bottles (NOT water bottles!) get at least 2 of them
-Cardboard or coroplast (the stuff cheap signs are made of)
-batting, foam, paper strips.... whatever you find for the Eggstronaut...
-Scale (as in drawing to scale)
I'll also provide a marking sheet at the end so you can use it in your class.
Right, then. Lets get started...
Step 1: Day 1. The Introduction
Tools and Materials:
-a couple of 2 liter bottles
-Big sheets of paper. (i cut stuff off a roll from the art guys...)
-Metersticks (yardsticks for the people south of me ) :-)
-Lots of pencils.
-a computer with examples of water-bottle rockets from the web. check out youtube... I use a TV attached to my ancient computer... not impressive but works fine...
After you show the kids examples from the web they will be hard to hold back. Its pretty cool. I start asking questions like these:
-How does it fly?
-Why are some short and some long?
-Some rockets have 2 fins, some 6... why?
-What about the fin size?
I cover each of these points on the board. What you want to coax out of them is:
The rockets fly by pressurizing air with water. (more on the water next day) This is important because the "Booster Bottle" which is pressurized ****MUST**** be a bottle for carbonated drinks and MUST MUST NOT be punctured or cut AT ALL. It will explode if otherwise. I've done it and it is really scary. Funny but scary.
Long rockets (double length) work best. You can chat about what RATIO is now... Suggest methods of lengthening the rocket. (tubes, extra bottles)
Fins that are Symmetrical with 2-4 are best. Keep them small... explain that the rockets explode off at more than 100kph and large fins will rip off. A good size is a triangle with Hypotenuse of 3-7 inches and bottom edge of 1-3 inches is good.
Now introduce the EGGSTRONAUT. Explain that if the passenger survives they will get extra marks. They love this. Go over padding and protection if you want but i find the kids come up with the most amazing ideas... better than mine! My only stipulation is that they have to make an escape hatch that can be used to insert and remove the Eggstronaut on the field.
Once the kids are ready i break them into groups of 2 or 3. Don't do 4... you always get at least one kid who is left in the cold. I pull out the paper and teach them about drawing objects to scale on the paper. You can trace out a bottle or two which helps them visualize it.
Spend the remaining time working on design. You'll get a couple groups that finish the drawing in minutes... just send them back with revisions... measurements... notes... whatever you can make up :-) Make sure they draw the fins to size and they are being realistic about the egg and how it will get into the hatch.
Spend some time discussing materials. I ask the kids to bring bottles, long cardboard tubes, cardboard, coroplast and any packing material they will need. Its up to you. I supply basic tools and tape to build the rocket with.