TUTORIAL WATER ROCKET GLIDER 1. What is a Water Rocket glider? Water Rocket glider is a rocket-cum-glider that uses water as a propellant and then glides in air. It gets its thrust from water. This thrust provides the impulse which in turn provides height and velocity to the glider. The model glides using the velocity and height provided by the initial impulse It is very easy to make a water rocket glider. Most of the required materials are available in the scrap room of your house. Here, we will show you how to make a rocket out of a plastic bottle. 2. How does a Water Rocket work? Water is filled into the bottle up to 1/3rd of total volume. Air is filled into the remaining part of the bottle (you can use a foot pump or a cycle pump to fill air) to increase pressure to a desired limit. The mouth of the bottle is then opened suddenly. Due to high pressure inside, water rushes out of the bottle at good velocity. Now, according to Newton's third law, the bottle gets a thrust in opposite direction. And your rocket is launched!!! The problem now is to launch it in a defined direction. Let us develop a launch pad for this purpose. TECHKRITI 10 Page 1
3. What are the required materials? 1) Plastic bottle (preferably of at least 1 liter in volume) 2) Cycle valve 3) Cork 4) Cable Ties 5) PTFE type 6) A PVC pipe (with outer diameter equal to the inner diameter of your bottle) 7) A PVC pipe with larger diameter 8) Balsa wood or Plastic (used in folders or stick files) or cardboard or other material that can be used to make wing. 9) Bondtite, Bondquick (glue) 10) Cutter, sandpaper etc 4. How to make a water rocket? The collar is a pipe that can slide over the inner pipe. When pushed up, it will close the cable ties (they are in open position in the above picture). When closed, they will hold the bottle and will not allow it to move while pressurizing. The collar is pulled down to release the bottle when desired pressure is reached. TECHKRITI 10 Page 2
STEPWISE PROCEDURE: a. Attach the cable ties to the pipe at the desired position. b. Attach a T junction to the other end of the pipe and close one of its openings. c. Now, the launch pad is ready. TECHKRITI 10 Page 3
d. After filling water in the bottle, place it in position as shown in the picture in 6 th slide, move the collar up, pressurize the bottle by pumping in air, and pull the collar down after desired pressure is reached. e. You can see the bottle go up to a good height. 5. How to convert water rocket to water rocket glider? Once all the water is propelled out of the water rocket, it becomes a normal projectile. However, this projectile can be made to glide by adding proper lift producing and stabilizing surfaces to it. The lift producing surface is called a wing and the stabilizing surfaces are called vertical and horizontal stabilizer. You can use different types of wing with different dimensions depending upon the size of your model. For more details on wing and stabilizers, refer to the tutorial on glider making. Various materials like wood, cardboard, plastic can be used for making wings and stabilizers. We suggest you to use Bondtite (glue) to attach your wing and stabilizers to the bottle. Make sure that bottle is not damaged while attaching the wings because this may cause leakage from the bottle. Also ensure that model is properly balanced. We are including some pictures of water rocket for your reference. 6. How to balance model (for making it good glider)? Once you attach wing and stabilizers to model you need to balance the model to give it good gliding capability. Mean Aerodynamic chord (MAC) = 2/3C R [ (1+r )-( r/( 1+r )) ] Where Taper ratio, r = CT/C R C R = root chord of wing and C T = tip chord of wing. Therefore location of Aerodynamic Centre of wing = 0.20-0.25 Of MAC along MAC from leading edge of wing as shown in fig. Now balance your model about this point i.e. put your fingers tip at aerodynamic center (at both half of wing) and balance the model. In balanced state model should be horizontal. You can read about the terms used here and about the concept of glider in glider tutorial. Glider tutorial can be downloaded from Tutorial page of Impulse Event. TECHKRITI 10 Page 4
Wing Geometry C R 0.20C - 0.25C MAC (C) Aerodynamic Centre of wing C T TECHKRITI 10 Page 5
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6. How to launch? TECHKRITI 10 Page 7
7. What more? Now, since you have made your rocket and launch pad, it s time to make it more efficient. Chance to use your creativity here. Here are a few tips: Try to make the rocket streamlined and try to give `rocket shape to the bottle. Give dihedral angle to the model to stabilize rolling movement. You can also add more bottles to make a bigger rocket. ALL THE BEST!! Team TakeOff Techkriti 10 TECHKRITI 10 Page 8