The World's Largest Water Rocket (IMAGE) National Physical Laboratory Caption On Wednesday, 15th June the National Physical Laboratory (NPL), the UKs National Measurement Institute, successfully launched the world’s largest water rocket. Water rockets are created from plastic bottles, made aerodynamic by nose cones and fins. The rocket is part filled with water, and air is pumped in with a foot pump. When the rocket is released from the launcher, the high pressure inside the bottle equalizes with the air outside, pushing the water out through the hole in the bottom, propelling it forward. The record setting rocket was built from over 100 fizzy drink bottles and measured 3.4m long. The record was set as part of an the NPL Water Rocket Challenge, an annual event to encourage local schoolchildren to get interested in science. Credit NPL Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.