Water Water Rocketry Workshop Welcome ! Fjodor Islamaj - South High CS Fredericka Solomon - Worcester East Middle Mr. Reidy - Abby Kelley Dr. Lynne Geitz - Worcester East Middle Glenn Tucker, Debbie Bastien, and Debralee Seles - Goddard School Dr. Abigail Slayton – Westborough Schools Saturday May 10, 2008 WPI Physics Department

Worcester Polytechnic Institute 2 The teams! 5 schools represented 11 teams to-date 49 team members in all ~ Tell us about your teams ~ Remember to send us signed parents permission slips!

Worcester Polytechnic Institute 3 A streamlined event… One goal: –Land the rocket in Goddards Circle –Size of Circle? –Poster contest? Five attempts per team 30 meters to the circle Up to 60 psi is now allowed

Worcester Polytechnic Institute 4 Design with Safety in Mind! Safety goggles required in launch area 60 psi maximum allowed pressure Use light-weight materials Use a soft nose cone Use guide rod for predictable launch direction Use fins for stability in flight (prevent tumble) Inspect bottle after each launch Beware and be aware of other teams near you Avoid low launch angle – slosh leads to dump!

Worcester Polytechnic Institute 5 How does a water rocket work? Just like a spring! Stored Energy Both systems are examples of Newtons 3 rd Law of equal and opposite action. Compressed spring Compressed air Release Start with no compression

Worcester Polytechnic Institute 6 Effect of air resistance during flight The retarding force of air on rocket is proportional to velocity squared (double the velocity and quadruple to retarding force). In earths atmosphere: reduced height and range best launch angle varies asymmetric trajectory If earth had no atmosphere: 45 deg launch for max range parabolic trajectory Height Range

Worcester Polytechnic Institute 7 Variables affecting range: Launch angle Air / Water ratio Tank pressure Size of exhaust nozzle Size of fins Shape of nose Mass of rocket (empty) Relative positions of C.O. Mass and C.O. Drag

Worcester Polytechnic Institute 8 A few tips… Bring spare parts: –bottles –fins –stoppers Bring tools: –duct tape –utility knife –pliers Practice a lot!

Worcester Polytechnic Institute 9 Going forward… Goddards Cup –Each year, a new science challenge Goddards Circle –Join and help develop next years activities Science Outreach IQPs –Presenters: Marketing science on location –Mentors: Team building over the full school year

Worcester Polytechnic Institute 10 Physics is hands-on, so lets go build some rockets!