Modern Evolution Of The Classic Water Rocket

Whether it was home-built from scraps or one of the various commercial versions that have popped over up over the years, there’s an excellent chance that the average Hackaday reader spent at least a couple of their more formative summers flying water rockets. You might not have realized it at the time, but with shirt soaked and head craned skywards, you were getting a practical physics lesson that was more relatable than anything out of a textbook. Water rockets are a great STEM tool for young people, but in a post-Fortnite world, the idea could use a little modernization to help keep kids engaged.

With his entry into the 2019 Hackaday Prize, [Darian Johnson] hopes to breathe some new life into this classic physics toy. His open source kit would provide a modular water rocket intended for a wide range of ages thanks to various payloads and upgrade options. The younger players would be content to simply see it take off, but high school students could outfit the craft with an electronic payload to capture performance data or an automatic parachute.

[Darian] has been building and flying rockets with his own children and other youth in community for years now, and has found them to be a huge hit. They became so popular that he started thinking of a way to not produce them in larger quantities, but make them stronger so they would survive more flights.

Of course, the fuselages are easy enough; there’s no shortage of one-liter bottles you can recycle. But for the nose cone, fins, and ultimately even the launch pad, [Darian] turned to 3D printing. This allows him to continually optimize the design while delivering repeatable performance. When he had a semi-printable water rocket on his hands, he started to wonder if he could get older kids interested by adding some electronics into the mix.

His current proof of concept is a flight data recorder using a Adafruit nRF52 Bluefruit LE Feather, a BMP280 sensor to determine altitude via barometric pressure, and an SD card breakout for local data storage. Long term, [Darian] wants to be able to stream flight data to student’s phones over Bluetooth, with the SD card providing a local copy which can be analyzed after the flight.

[Darian] has leaned heavily on the open source community for the various components of his water rocket kit, and is dedicated to giving back. He hopes that his final kit will allow communities to create engaging STEM activities at little to no cost. This includes creating a repository of lesson plans and designs contributed from others experimenting with water rockets. It’s a noble goal, and we’re excited to see how the project progresses.

Build Your Own Two-Stage Water Rockets

Water rockets are one of the most fun and exciting science-adjacent activities one can take part in during the summer, and are popular with children and adults alike. Designs range from a bike pump with a cork in a bottle, up to significantly more advanced hardware. [Air.command]’s two-stage water rocket definitely fits into the latter category.

The build is initially somewhat confronting in its complexity, but after a thorough read-through the operating principles become clear. It’s an all-mechanical setup which relies on the weight of the upper stage and the initial acceleration of the rocket to keep the two stages coupled. It’s only when the first stage stops delivering thrust that a spring forces the two stages apart, and the upper stage rockets ever higher.

Parts-wise, everything is fairly accessible – with pieces cribbed from garden hose fittings, retractable pens and other household ephemera. It’s not the easiest thing to put together, but with perseverance and some tweaking and tuning, it’s definitely achievable for the home gamer, with no advanced tools or techniques required.

Now that you’ve got a two-stage rocket under construction, you might want to consider upgrading your launchpad. Video after the break.

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Nose Cone Parachute Deployment From A Soda Bottle, Rubber Band, And Servo

nose-cone-parachte

This piece of engineering is so simple and elegant, you’ll want to build a pretty serious water rocket just so you can try it out. It’s an automatic parachute deployment system that you build into the nose-cone of your rocket. The main portion of the build is made out of plastic soda bottles (2 liter size) to end up with a chamber to store the chute, as well as a friction joint that holds the thing together.

The video after the break shows a complete tutorial on how to build one of these. It starts by tracing out a sine-wave-like pattern on the wall of the bottle. The staggered tongues that are left after cutting along this line make up the friction joint. After gluing a cone (the blue thing) to the bottom of the bottle, it receives the parachute and is then slipped over another bottle that makes up the body of the rocket. The rubber band wraps around the outside of the chassis, holding those plastic tongues in place. The loose end of the rubber band is hooked around the horn of a servo motor, which can then be triggered remotely, or by using a sensor of your choosing. There is even a spring made out of a loop of plastic bottle — you can see it just on top of the chute in the image above.

Need a launching system that is as fancy as the parachute system? Here you go.

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Build Your Own Water Rocket Launcher

We feel like the days when you want to play in the water are far behind us. But if you can still find a warm afternoon here or there this water rocket launcher build is a fun undertaking. We figure most of the time spent on the project will be in shopping for the parts. They’re all quite common, and once you have them on hand it can be assembled in under an hour.

The concept is simple, but that doesn’t stop people from building rather complicated water rocket rigs. This one which [Lou] devised is rather simple but it does offer connections to a hose and air compressor (the alternative being to fill the bottle with water ahead of time and use a bike pump for air pressure). PVC is used to connect the two inputs to the bottle via a pair of valves. The bottle is held in place while water and air are applied. The launch happens when a pull on that rope  releases the bottle.

Check out the build process and bottle launch after the break. We think that rocket needs a few fins.

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Building A Better Water Rocket Launchpad

School will be starting again in a few weeks but it’s not too late to enjoy a little time with your kids. This water rocket launcher lets you do just that. Built using the frame from an old grill, a soda bottle takes its place on the upturned PVC pipe. There’s a connection for your garden hose that allows you to inject water into the bottle. From there, a compressor connection pressurizes the bottle in preparation for launch. Watch it happen in the video after the break. That bottle could use some fins and a nose cone but there’s no denying the delight the kids are enjoying when they chase after the downed craft.

If you’ve already got a compressor and some empty 2-liter bottles you might also pick up some extra PVC to make this pressurized water cannon.