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3,2,1, Blast Off!

Division: A – Elementary

NC Essential Standards Alignment: 3.P.1, 5.P.1, Science as Inquiry

Event Rules: 3,2,1 Blast Off! Rules

Event Score Sheet: 3, 2, 1 Blast Off! 2021 Scoresheet

Clarifications:

Description:

Prior to the tournament, teams will construct up to two rockets designed to stay aloft for the greatest amount of time. In 2021, the pressure vessel must be a 2-liter bottle. (updated 7/13/2020)

*** Note: Some soda manufacturers have changed the size of the neck of their bottles. Please make sure the inner diameter of your bottle neck is still 2.2 cm, not the new reduced size of 2.1 cm. The 2.1 cm necks will not fit on the launcher. The easiest way to test this is by sliding a piece of 1/2 inch PVC into the bottle. If it fits loosely, the bottle will go on the launcher. If the PVC sticks and you have to apply any force to slide the PVC in, the bottle will not go on the launcher.***

Materials:

Must bring rockets, carbonated beverage bottle labels (if removed), and safety glasses. Teams may also bring funnels, measuring cups, and/or other tools to help prepare their rockets.

Event Leaders will provide water rocket launcher, water, score sheets, and timers.

Scoring:

High score wins. Score will be determined by highest time aloft of the 2 rockets in seconds (measured in tenths of seconds).

Common Mistakes:

– Be sure that the pressure bottle remains intact. Repeated testing and hard landings can damage your pressure bottle. Check it frequently for scratches and weak spots that may compromise the structural integrity, and replace the bottle as needed.

– Find the ideal water level for your rocket. While 100% air will give you the maximum potential energy, it has very little mass and therefore very little momentum to carry the rocket. Likewise, 100% water will have great mass, but very little potential energy to give it momentum. Don’t wait til the day of the competition to decide how much water to use!

– If you remove the label from your pressure bottle, be sure to bring it to the competition or you will not be allowed to launch the rocket.

Remember, only one launch is allowed per rocket! If you want to utilize both launch attempts, you must bring a second rocket! Varsity and JV teams must each have their own rockets and may not borrow each other’s rockets to launch.

Recommendations:

– This event requires safety glasses, meaning the kind that look like sunglasses will work just fine. These are MUCH easier to see out of. Your local home improvement store carries cheap versions for under $4. Safety goggles (the chemical splash kind that most schools have) have a tendency to fog up, making it hard to see.

– For transporting rockets with less risk of damage, glue/screw a bottle cap to a cardboard or wood base and simply screw your rocket onto it to make it stand up. For added protection, place this entire setup inside a 5 gallon bucket to protect fins, etc.

– If you are concerned about the integrity of a bottle that you have found to use for your pressure vessel (It looks unaltered but you’re just not sure) you can pressure test it. To do this, fill the bottle completely with water. This ensures that the amount of air (and potential energy) inside is minimal, so that if the bottle does fail it should simply rupture and not explode. Then pressurize it to 1 1/2 times the competition psi (competition requires 60 psi, so test to 90 psi). While this is not a way to bypass safety regulations, it can give you peace of mind and save you a lot of build time by preventing building on a damaged bottle.

– Rather than trying to cut holes through your rocket’s non-pressurized plastic components, use a hot needle or hot ice pick to poke a hole with smooth, rounded edges.

– The driving force behind a rocket launch is the combination of air and water under pressure. The air that you pump into the bottle compresses, giving you a higher pressure (60 psi in this year’s rules). When the rocket is released the air expands rapidly, which forces the water out of the neck of the bottle and propels the rocket.

– Angling your fins slightly to one side will cause the rocket to spiral on its way up, creating stability much like throwing a football in a spiral.

FAQs

  1.  Can you cut a slit in the ping pong ball to attach the parachute shrouds?  Can you sand the ping pong ball to get the tape to attach better?  Rule 9g requires use of a standard ping pong ball.  

Do not alter the ping pong ball, you can tape strings to it or tie things around it, but cutting it, sanding it, and gluing things to it would make it not “standard” any more.

2.  What is meant by rule 10f?

This is if the ping pong ball falls off between the point of the rocket being pressurized to immediately after leaving launch pad.  Assuming you have ping pong ball, your minimum time should be 1 second for each launch.

3.  On a windy day, there is a good chance of multiple rockets hitting rule 10f, which could lead to some ties with combined rocket scores of 2 seconds (1 +1).

We will do our best to have students reposition the ping pong ball if it drops before launch.

4.  Regarding rule 10f, there was a question whether you could have part of the rocket separate with the ping pong to act as a glider on the way (kind of like the space shuttle).

As long as the ping pong ball least separates from the pressure chamber portion of the rocket, whatever else you want to attach to it to help bring it back to earth is fine – gliders would be a cool idea!

5.  Do you have to have a recovery system?

If the ping pong ball separates from the rocket and falls to the ground with no parachute, this would still be Tier 1.

Event Resources:

Youtube explanation for 3,2,1, Blastoff (2020 rules)

Launch video (shows parachute separating from rocket)

3,2,1 Blast Off! 2018 Coaches Clinic Presentation (2019 Rules)

How to Build a Water Rocket

Nerds, Inc (excellent rocket launchers like the ones used at NCSO tournaments)

Wiki How – Step by step videos on how to build a bottle rocket – not specific to NCSO event rules

Tim Hesterberg’s How to Make a Water Bottle Rocket Page – not specific to NCSO event rules

Media: