Rockets - launching, fins, friction, worksheets and more ...

From the simulation you would have found that where the majority of the mass in the rocket was located, governed to a degree, how high your rocket went. In a similar way, the centre of gravity of your rocket and the centre of pressure are important as well. Below are some suggestions worth trying.

Consider the following points when launching your rocket A water rocket is going to make things wet. Use rigid plastic for fins - eg fins can be made from the sides of a two litre square milk carton or the lid of an icecream tub. Any firm plastic or water proof material that is light and easy to cut can be used. You can try many different shapes for your fin. The most popular shape though is one with the outer edge roughly the shape of a semi circle. Try and ensure that the surface of the bottle, fin and nose cone if used is free of any roughness - a rough surface means added friction, hence less altitude will be reached. Attaching a nose cone and/or fins needs to be done without adding a rough surface. To hold a fin at right angles to the bottle can be achieved by using a bobby pin bent in an "L" shape where one part of the L is attached to the fin and the other bent to meet the curve of the bottle and attached using tape. Test your rocket when you believe it is completed. Using several metres of string, tie the rocket around the middle so that it balances. If you added a nose cone (extra weight towards the front), the balance point will be towards the nose. When the rocket hangs level, a small piece of tape should be temporarily fixed to the string and bottle to keep the string from slipping. The rocket is then twirled in a circle. If the rocket tumbles while circling, it is not stable and needs more nose cone weight, bigger fins, or a combination of both. If the rocket circles with the nose always pointed forward, it is stable and ready for flight. For additional information on stability visit Model Rockets US webpage "Understanding Model Rocket Stability". If you are using an Aquapod, fill approximately 1/3rd of the bottle with water. If you are not doing just a hit and miss trial, use a measuring cylinder and fill the bottle with 600mL of water. Lock the bottle to the Aquapod ensuring the lock has engaged the bottles lip. Ensure that the release cord is lying on the ground and no one walks or runs over it. Connect the pump and create 60psi of pressure in the bottle. Have all move back and pull the cord to release the rocket. Rocketry worksheets Explanation page for simulator Worksheet for simulation Worksheet to record all your launches For additional information in making your rocket click here to visit NASA's water rocket version. As a rocket has a trajectory, that is, a rocket rarely goes straigh up and straight down but travels in the shape of an arc, visit NASA's Trajectory page for additional information - click here. One last suggestion. We recommend you only change one variable each time you adjust your launch. Key: psi stands for pounds per square inch - metric unit is the Pascal - Pa.