3. Pastikan rakan-rakan yang berada di sekitar tapak pelancaran berjaga-jaga semasa roket payung terjun telah terbang ke udara 4. Pastikan rakan-rakan anda sentiasa memerhati ke atas selepas pelancaran roket paracut dan perhatikan muncung/kon roket tersebut di mana ia akan jatuh.
• To trace the bottle's shape on the fin material, place the bottle directly under a light source. • . "Swing Testing" is a quick way to determine if a rocket has reasonable stability. This test is done by tying a string around the rocket at its CG and swinging the rocket around. • Fins cause very little drag and do not weigh very much. A non-stable rocket that is flying sideways is creating a lot of drag. Non stable rockets have a lot of problems with pre-deployment of their parachute
• Parachutes are more efficient with more shroud lines. Shroud lines hold the shape of the parachute and keep air from burping from the chute. • Parachutes should be as large as possible while still meeting overall length requirements and efficiency standards. • Parachute efficiency is improved by using the correct shroud length. Shroud lengths should be between 1.2 to 1.5 times the parachute diameter.
• The best parachute material that I have found is dry cleaner bags. If you request the bags used by commercial cleaner for drapes or wedding dresses you may find one large enough for your parachute. • The best material for shroud line is nylon upholstery thread. • How much water? 1/3 of the capacity of the bottle will get you close. Use simulator listed on page 4. • When humidity is low and there is no chance of rain, you can use talc to keep the chute from having static cling.
• The best folding technique for passive deployment is to zig zag fold the cute, starting from the top to bottom. When you fold the chute to the shroud lines, gently make a couple of wraps with the lines. You want to use as few wraps as possible so that the chute will deploy quickly. • The parachute should be attached securely to the rocket. It can be glue or tied. • Make sure that your cone sits securely on the rocket. I have seen numerous rockets disqualified due to cones shifting during pressurization or by being blown off by the wind.
• Practice many times in all conditions including rain. • Have a written procedure and follow it every time. The teams I coach follow step by step through their checklist everytime even though they know it by heart. Airline pilots and surgeons both use checklists, shouldn't you? Laminate your checklist!
• How much air pressure do I use? Easy question, all that is allowed. The more stored energy, the higher you go. • Use this flight simulator to determine the best amount of water. http://homes.managesoft.com.au/~cjh/rockets/si mulation/
• Make sure that you have a waterproof box to store your rocket and supplies. Also make sure you have an umbrella to cover the rocket while staging and before launch. Bring rain gear for yourself. The last 2 years at nationals we have had intense rain and many rockets were damaged. • Try not to use paper, cardboard or wood components in the rocket. If you do, attempt to waterproof them.
• Bring too much clothing. You don’t have to wear it, may want to. When cold or wet it is hard to concentrate. • Know the launcher that will be used at the event you are going to attend. This is a particular concern for rockets that have fins that are swept below the flange on the bottleneck. Many launchers including the typical "Bent Fork Launchers" and the NERDS launcher will not launch rockets with swept fins. If you plan to use a swept fin rocket, I recommend that you • contact the event supervisor or event director to determine what type of launcher will be used. In the past at nationals a launcher that is capable of launching all typical rocket fin configurations has been used, but it still doesn’t hurt to check.
• Mark your rocket with the correct water level as a double check. If you are going to be launching off a launcher where you will have to tip your rocket, rather than the launcher tip ping for loading, always put in a little too much water. As you tip your rocket you will always lose a little water. You can lift up on your rocket gently to let out a little water while on the pad. (Don't get too bent out of shape if you don't have exactly the correct amount of water, a few ml of water will not make that much difference)
Bottle Rocket Resources (Bottle Rocket Are Commonly Referred To As Water Rockets) Recovery: Vertical, Horizontal Systems http://hometown.aol.com/powerdeployment&Passive Dave Johnson Air Flap http://dogrocket.home.mindspring.com/WaterRockets/ Gary Ensmenger - Balloon http://www.h2orocket.com/topic/balloon/balloon.html Nerds Recovery Systems http://tc.unl.edu/rbonnstetter/rockets/recovery.html Paul Grosse http://ourworld.compuserve.com/homepages/pagrosse/h2orrecsys1.htm Ulrich Hornstein http://home.t-online.de/home/u.hornstein/wr.htm Aaron Allen - VDEN http://hometown.aol.com/a1allen/Aaronswaterrockets.html