How to Make a Bottle Rocket That's Great

A Great Bottle Rocket.

This article shows you how to make a bottle rocket designed to hold and reliably deploy a parachute. It doesn't show you how to make a parachute, as this would require its own article.

Before you begin, read through all the steps to make sure you understand what the final result will be; this will help you correctly design the rocket.

Things You'll Need

• Three 2-liter bottles of soda
• 2 pieces of canvas board
• 2 pieces of manila or construction paper
• 1 dowel rod that is 5/8" or 3/4" wide and either 1 foot or 1 meter long.
• Roll of packing tape.
• Box of paper clips
• Glue sticks and hot glue gun (preferably low-heat)
• Two 1" long metal hinges (It is best that there is a screw hole in the bottom center of one of the two hinges).
• Permanent marker
• Wire cutters
• Needle-nose Pliers
• Ruler
• Scissors
• Knife
• Razor blade (optional)
• 2 meters of string (non-elastic)
• Rubber bands (best to have a mixed bag of various lengths and resistances.)
• 10 to 30 pennies
• Freezer
• Hole puncher (optional)
• Another person (optional)

Instructions

1. Empty all the bottles of their contents.

2. With the cap off, place one of the 2-liter bottles in the freezer. Wait at least 30 minutes.

3. With the cap in hand, remove the bottle from the freezer. As soon as the bottle is removed, waste no time--put the cap on and twist tightly. As the cold air warms, it will expand. When you later hot-glue items to the bottle, it will deform less.

4. 

   Take another 2-liter bottle, and cut out a small section about 1 1/8" to 1 1/4" tall. Cut close to the bottom as this bottle will be used later.

5. 

   Make one vertical cut down the ring.

6. 

   Wrap the ring around the bottom of the main bottle. The ring isn't supposed to wrap all the way around. The distance from the bottom of the bottle to the bottom of the ring should be very close to 1 1/2".

7. 

   Put a medium to large dot of hot glue at one end, and wait until it cools. Continue around, placing one dot at a time. The plastic ring will deform a little bit--this is a good thing.

8. 

   Hot-glue one hinge to the plastic ring. This should not be the hinge with the screw hole in the bottom center. If the cap is facing toward you, the hinge should open toward you.

9. 

   Take the hinge with the screw hole in the bottom center. Place the hinge in line with the first hinge. There should be 3 3/4" between the center of the top hinge and top of the bottom hinge. Hot-glue in place.

10. 

    Wrap the string around the circumference of the bottle. Use the marker to mark where overlap begins.

11. 

    Measure the length of the string and divide by two. Measure from one end of the string to the number you got, and make a mark.

12. 

    Line the end of the string up with the spot between the two hinges. Wrap the string around. Make a tic mark on the bottle below the mark on the string.

13. 

    Cut a paperclip into a hook shape. Place the hook so that it is aligned with the tic mark. With the bottom of the rocket positioned toward you, you should see the hook bend outward in your direction. The distance from the outward bend to the bottom of the bottle should be 3 7/8". Hot-glue the hook in place.

14. 

    Take the manila paper and cut out a 3x3 inch square. Round the corners a bit to create the wind flap.

15. 

    Find the bottom center hole of the hinge closest to the bottom of the rocket. Place the wind flap against the hole. With a permanent marker, trace the hole onto the wind flap.

16. 

    Remove the wind flap. Use the hole puncher to punch out the the traced hole and then some. If you don't have a hole puncher, use the scissors or knife to cut it out.

17. 

    Hot-glue the wind flap to the inside of the hinge closest to the cap. The hole that was punched out and the hole in the hinge should align.

18. 

    Take the bottle you cut the ring out of and use it to cut a 4 1/4" wide, 4 1/2" tall pressure flap out of it.

19. 

    Round the edges of the flap.

20. 

    Use the permanent marker to add flames. (I'm not going to force you to do it, but it will make your rocket look cooler--I promise.)

21. 

    With the knife, poke a hole 3/8" up from the bottom of the pressure flap. It should be the diameter of a paperclip and centered horizontally on the flap.

22. 

    With the knife, poke another hole 1 1/8" from the top of the pressure flap. It should be the diameter of a paperclip and centered horizontally on the flap.

23. Cut and bend a paperclip straight. The length when straightened out should be about 3 1/2".

24. 

    Take the wire cutters and rotate then around the end of the paperclip. Apply very light pressure to create a notch. Make about 9 notches over the last inch of the paperclip.

25. 

    Place the pressure flap on the glued-down part of the hinge closest to the bottle cap. When the paperclip is bent into the Z shape, the flap must be in this position, and the paperclip needs to go through the bottom center hole of the hinge.

26. 

    You will soon bend the paperclip into a Z shape. The top and bottom sections of the paperclip should be perpendicular to the middle section.

27. 

    The middle section should be just barely taller than the top of the bottom screw hole in the hinge. The length of the top section should be about 7/8" long, and the length of the bottom section should be about 2" long.

28. 

    While bending the paperclip into the correct shape, check it frequently by inserting it in the hole in the bottom of the pressure flap. The top two sections should be above the flap, and the bottom section should be under the flap. Bend the paperclip into the correct shape as described above.

29. 

    If everything is aligned properly, insert the paperclip in the hole at the bottom of the pressure flap, and hot-glue in place. Work very slowly. The pressure flap needs to keep its curved shape as much as possible, and not deform. Use only tiny dots of glue at a time, and wait for them to cool before proceeding with the next dot.

30. 

    Finish securing the paperclip with tape.

31. Cut and bend another paperclip straight. The length when straightened out should be about 2".

32. 

    Bend the paperclip into a Z shape. The top and bottom sections of the Z should be perpendicular to the middle section of the Z. The middle section should be about 3/8" tall, the top section about 1/2" long, and the bottom section about 1" long.

33. 

    Insert the paperclip in the hole at the top. The top two sections of the Z should be on the outside of the flap, and the bottom 1" section of the Z should be under the flap. Hot-glue in place. Work slowly and use dots to avoid deforming the flap.

34. 

    Finish securing the paperclip with tape.

35. 

    Place the tapered end of the pressure flap on the empty hinge. Again, make sure the paperclip on the opposite end goes through the bottom center hole of the opposite hinge by at least 1/8".

36. 

    Cover the hinge in hot-glue, and place the flap on top of it. Apply pressure until the glue cools.

37. 

    Add hot-glue around the edges of the hinge, and in the holes, but work slowly. Allow one dot of hot-glue to dry before adding the next.

38. 

    Add tape to further secure the flap in place.

39. 

    If the overhang is more than 1/8", trim to 1/8".

40. 

    Test the operation of the flap. Set the wind flap in the vertical position. The paperclip should fit in the bottom center screw hole of the hinge and "lock" in place (due to using the wire cutters to create the notches). Turn the rocket so that the cap is touching the floor. The wind flap should be relatively secure. It should not fall down, even with minor jarring of the rocket.

41. 

    Finish the main rocket body by adding three fins. Take the canvas board and trace a fin in the shape of a trapezoid that measures 1 1/2" on one parallel side, 3 1/8" on the other parallel side, 2 1/8" on one non-parallel side, and 3 1/8" on the other non-parallel side. The measurements don't have to be exact, but try to keep the general shape.

42. Cut the pattern out. Use either scissors or the razor blade and ruler.

43. Trace the pattern in two more locations on the canvas board. Cut these out as well.

44. 

    Use a desk or other piece of furniture for this step. Measure 5 3/8" up from the floor. At this point, tape the marker in place. It is very important that the marker is secure.

45. 

    Move the bottle over to the marker. With the bottle just touching the tip of the marker, rotate the bottle 360 degrees so that a horizontal line is drawn on the bottle. If necessary, ask another person to hold the marker in place while you rotate the bottle.

46. 

    Take a string and wrap it around the bottle and then some. Make a mark on the string where it has wrapped around once.

47. Lay the string flat. Measure the length of the string from the end of the string to the mark. Divide this number by three.

48. 

    Measure the length from the end of the string to the number you got and make a mark.

49. 

    Measure the length from the end of the string to the number you got times two and make a mark.

50. 

    Wrap the string around the horizontal line on the bottle. Make vertical tic marks underneath each mark on the string.

51. 

    Slide the string straight up. Make vertical tic marks underneath each mark on the string.

52. 

    Line the ruler up with the two tic marks and connect the marks; extend the line down until the bottle begins to curve.

53. 

    Place a fin along one of the lines. The top of the fin should be touching the horizontal line. The long slant should be facing upwards with the long side against the bottle. Add a few dots of glue along one side of the fin. Work slowly, placing only a few dots at a time to prevent the bottle from deforming.

54. Add some dots to the opposite side of the fin. Gradually fill out the area between the dots. Use plenty of glue, as the fins are the most likely part of the rocket to break off after launch.

55. For extra security, add packing tape to both sides of each fin.

56. The main body of the rocket is now complete. Now to start on the top section which will complete the parachute deployment system, hold the parachute, and stabilize the rocket. Start by finding the dowel rod.

57. 

    The dowel rod should be about 13" in length. Measure to 13" on the dowel rod, and make a mark.

58. 

    With a knife, cut away some of the dowel rod at that point.

59. 

    When sufficiently cut away, break the dowel rod in half across your leg.

60. 

    Take the third empty soda bottle and cut it so you have about a 6 3/8" section. The top cut should be about 2 3/4" from the bottle cap.

61. 

    Trace the circumference of the top of the section you just cut out onto the canvas board.

62. Cut the circle out.

63. 

    The circle should just fit on top of the plastic cutout.

64. 

    Hot-glue the circle in place by gluing around the outside of the cutout. In this case, you should be able to work a little faster. Always watch to make sure the bottle isn't deforming too much.

65. 

    Hot-glue the circle from the inside of the bottle as much as possible.

66. For extra security, add tape around both the outside and inside of the circle.

67. 

    Fill the outer edge of the circle with hot glue.

68. 

    Place the top piece of the bottle (left over from the cutout) on top of the circle. Hold it there until the glue cools.

69. 

    Hot-glue the outside of the top piece to the circle.

70. 

    For added security, add tape around the circumference of the circle.

71. 

    Fill the rough end of the dowel rod with as much glue as it will hold.

72. 

    Flip the dowel rod upside-down, and put it inside the top part of the bottle. Hold there until the glue cools.

73. 

    Add hot-glue around the mouth of the top piece.

74. 

    Stack the pennies and add tape around their circumference.

75. 

    Hot-glue the stack of pennies to the top of the dowel rod.

76. 

    Secure the pennies to the dowel rod with tape.

77. 

    Cut a small 3x3 inch section from the manila paper. Wrap this into a cone.

78. Put a piece of tape around the cone to keep it from coming undone.

79. 

    Cut the cone so that the bottom diameter is the same as the diameter of a penny.

80. 

    Place the cone on top of the stack of pennies. Hot-glue the cone to the pennies.

81. Wrap tape around the cone and stack of pennies to finish securing the cone in place.

82. 

    Place the upper portion of the rocket on the lower portion. If the plastic ring was successfully glued on, the upper portion should sit loosely on the ring which is connected to the lower portion. If the upper portion gets stuck on the ring, rotate the upper portion until you find a position where it doesn't get stuck. With the permanent marker, draw two continuous lines from the upper portion to the lower portion on each side of the hinge. These lines will help you to quickly align the rocket later.

83. 

    Place the upper half on the lower half, aligning the two marks near the hinge. On the opposite side of the hinge, make a continuous mark between the upper and lower parts of the rocket. The mark should be in line with the paperclip hook.

84. 

    Cut 10 paperclips into hooks.

85. 

    Place the upper half on the lower half, and align them. Hot-glue the first paperclip in line with the two paperclips on the pressure flap. It should be 1 7/16" from the bottom of the upper half. Hot-glue one dot at a time. It should only take 4 to 5 dots to secure it.

86. Do exactly the same thing to the opposite side. Except this time, you should be aligned with the paperclip hook on the lower section of that side.

87. 

    Go back to the other side and add four more paper clips upward and to the left of the one that's already there. Vertical spacing should be about 3/8", and horizontal spacing should be about 3/16".

88. Move to the opposite side and repeat the procedure exactly.

89. 

    The only thing left to do is add the rubber bands. Bring the upper and lower parts together and align them. Turn to the side opposite the hinges. Attach rubber bands of various sizes, and to various positions. When you stop holding the upper portion down with your hand, you want the rubber bands to pull the upper portion completely off. It should do so with ease, but shouldn't pull it off with too much force either.

90. 

    With the rubber bands in place on the opposite side, rotate to the side with the hinges and pressure flap on it. Raise the wind flap to the vertical position, and lock it in place. Attach a rubber band from the second hook on the pressure flap to one of the hooks on the upper level of the rocket. When you press the wind flap down, the rubber bands on the opposite side should pull the upper section off.

91. 

    When the rocket is launched, the wind flap is blown down. This would normally deploy the parachute. However, the pressure flap is now held down by the air rushing over it. Once the rocket reaches its apex, there is no air pressure to counteract the tension of the rubber bands on the opposite side. As a result, the rubber bands pull the upper section of the rocket off. The parachute is deployed.

92. 

    While this article doesn't show you how to make a parachute, attaching one is easy. Find the top of the lower half of the rocket. Tape the parachute string to the center of it. Make sure you use enough tape so that the parachute doesn't break off during flight.

93. 

    If you want to parachute both the top and bottom halves of the rocket to the ground, take the lower rocket and attach a separate string to the center of the top. Attach the other end of the string to the inner side of the upper half. Make sure the string is long (about 1 meter,) and stays out of the way of the parachute strings.

94. Take off the cap. Your rocket is now ready for flight. Add decorations to your rocket just for fun. Pictures of a similar rocket that uses the same deployment system is shown below.

95. 

    The deployment system with rubber bands.

96. 

    The deployment system on the side of the pressure flap.

97. 

    The deployment system on the side opposite the pressure flap.

Tips & Warnings

• Tape the upper and lower portions of the rocket together. Hold the rocket in both hands. Rotate your hands so the rocket is now resting on your index fingers. Slowly move your hands closer together until they touch. This is the center of gravity of the rocket. The closer this is to the top of the rocket, the more stable the rocket will be in flight, and the higher it will fly.

• Experiment to find the optimal amount of weight to put on the tip of the rocket. If you use too little weight, the rocket won't be as stable as it could have been, and won't fly as high. If you use too much weight, the rocket will be stable, but will be too heavy, and won't fly as high.

• Experiment with the length of the dowel rod. The longer it is, the more effective the weight on the tip will be. However, if it is too long, it could weigh down the rocket. If the dowel rod is not rigid enough, it could actually destabilize the rocket.

• Imagine holding the rocket in front of a wall. Shine a bright light on it and look at the shadow that's produced on the wall. The more surface area near the bottom of the rocket, the more stable the rocket will generally be. This is why fins are placed as low as possible on the rocket. Placing fins on the tip of the rocket would be chaos.

• It's very important that the fins are equally spaced and rigid. The exact shape doesn't matter too much, except that a shape that puts most of the surface area near the bottom of the rocket is best.

• Experiment with rubber band tension. If you can find very long rubber bands, try gluing hooks all the way up on the dowel rod. This may produce more force than with just regular rubber bands--or, the upper portion might get stuck.

• For a related bottle rocket article, check the resources below.

• For books related to rockets, check the resources.

• Don't let the fins overhang too much on the rocket. It might not fit on the launch pad.

• The mini cone at the top of the rocket will get damaged after launch. This won't affect performance much--however, if you don't like the idea of your rocket looking bad, bring some replacement nosecones with you to the launch site.

• Bring a roll of duct tape to the launch site. This is essential for emergency repairs, such as a damaged nosecone, the pennies breaking off, broken fins, detached pressure flap, detached pressure flap hooks, or any other random breakage. It will affect the appearance of your rocket, but it's better than having one that won't fly.

• Bring plenty of rubber bands to the launch site. Sometimes the rubber bands don't stay wrapped around the hooks and are lost.

• The glue gun is hot. Keep it in the same place while constructing the rocket so you know where it is and don't accidentally get burned.

• If using a razor blade to cut out the fins, apply a steady downward pressure to cut the thick canvas board. Keep your hands in a position so that if you slip, you won't get hurt.

Resources

• How to Make a Great Bottle Rocket Desiged for Distance
• Backyard Ballistics: Build Potato Cannons, Paper Match Rockets, Cincinnati Fire Kites, Tennis Ball Mortars, and More Dynamite Devices
• Illustrated Guide to Aerodynamics
• It's ONLY Rocket Science: An Introduction in Plain English (Astronomers' Universe)
• 50 Model Rocket Projects for the Evil Genius
• Handbook of Model Rocketry, 7th Edition (NAR Official Handbook)