Introduction: Water Powered Bottle Rocket
Eric Jordan Steph.
Step 1: Gather Materials
What you need:
Two (2) Two liter bottle of soda (empty)
One (1) Three liter bottle of soda(empty)
One (1) package of string
One (1) Roll of blue painters tape
One (1) cardboard box
One (1) painter's drop cloth
One (1) pair of scissors
One (1) tennis ball
Step 2: Create a Parachute Holder
Remove the "Straight" part of the second two liter bottle by cutting at the start of the top and bottom curves.
Step 3: Create a Nose Cone
For the nose cone we cut the top off of a 3-liter bottle of soda and slid it down over the 2-liter shaft. The basis behind the idea was to reduce friction between the nose cone and the rest of the rocket so that the parachute would be easier to deploy. We also rounded out the top of the nose cone using tape in order to make the top of the bottle rocket more aerodynamic.
Step 4: Create Fins
Using a protractor, draw a parallelogram that has angles of 120 and 60. Cut out the parallelogram and trace it and cut it out again twice so you will have three equal sized wings.
Step 5: PARACHUTE.
We used Mr. Hayhurts's Quick and Easy Bottle Rocket's parachute design in our project. This consists of making a circular parachute with reinforced holes for 16 strings. We used masking tape to reinforce the holes and used the straightest string we could find. The design can be found here: http://www.lnhs.org/hayhurst/rockets/
Step 6: Attaching the Wings
First, measure the circumference of the bottle. Then make a mark separating the circumference into thirds. Tape the wings the long way, up and down the bottle, on each of the marks. Make sure the wings are on the "Straight" part of the bottle. Placing them on the marks will ensure that they are equidistant. If you bend the wings all to the right at the bottom, it will help with the rotation.
Step 7: Pack Up the 'Chute
You need to package the parachute so that its small enough to fit into the rocket. When you do this, make sure that the bottom, where the air will enter to fill it up, remains slightly open and still at the bottom. Package the parachute by holding it open and folding it in half three times, or until it seems small enough. Then fold the top down towards the bottom twice so its nice and small. Always make sure that the opening is still open.
Step 8: Assembly
Place the Parachute holder from step 2 over the bottom end of the two liter bottle that has the wings. This should create a pocket for the parachute. Lightly place the parachute in there, as not to get it stuck, and then place the nose cone on top. Voila. You have a bottle rocket.
Step 9: The Physics.
'Mass and Fuel:' More mass that their is due to fuel means two things. First, it means that initially, there will be a greater Force due to gravity pulling it down, as F(g)=MA and M is greater. Secondly it means that there will be a higher maximum velocity. The water will accelerate the rocket, and since there is more water, it will allow for more time to accelerate. By the time there is no water left, a greater starting mass, due to fuel, will leave the rocket weighing much less and moving very fast.
Nose Design: The basis behind the idea was to reduce friction between the nose cone and the rest of the rocket so that the parachute would be easier to deploy. We also rounded out the top of the nose cone using tape in order to make the top of the bottle rocket more aerodynamic.
Fin Design: We made parallelograms becase Apogee Rockets recomended it. We read this article: http://www.apogeerockets.com/technical_publication_16.asp which suggested that rectangles and parallelograms make fins with the least amount of drag.
RETURN DESIGN: Inertia would cause the heavier nose cone to fall off when the rocket reached its maximum height. The parachute would be stuffed in the nose cone, attached to the tennis ball. The weight of the ball would then pull the parachute out of the nose cone, and the air hitting it from below will force it open and the ball will slowly fall to the ground.