Launch Pad for Air-Water Rockets is Good Clean Fun for STEM Students

We have fond memories of air-water rockets, which were always a dime store purchase for summertime fun in the pool. Despite strict guidance from mom to shoot them only straight up, the first target was invariably a brother or friend on the other side of the pool. No eyes were lost, and it was good clean fun that was mercifully free of educational value during summer break.

But now a teacher has gone and ruined all that by making an air-water rocket launching pad for his STEM students. Just kidding — [Robert Hart] must be the coolest teacher in Australia when Friday launch days roll around. [Mr. Hart] wanted a quick and easy way to safely launch air-water rockets and came up with a pretty clever system. The core task is to pump air into the partially filled water bottle and then release it cleanly. [Robert] uses quick-disconnect fittings, with the female coupling rigged to a motor through a bicycle brake cable. The control box has a compressor, the release motor, and a wireless alarm remote, all powered by a 12-volt battery. With the male coupling glued to the cap of a bottle acting as a nozzle and a quick, clean release, flights are pretty spectacular.

There are many ways to launch an air-water rocket, from the simple to the complex. [Robert]’s build leans toward the complex, but looks robust enough for repeated use and makes the launch process routine so the kids can concentrate on the aerodynamics. Or to just enjoy being outdoors and watching things fly.

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Copenhagen Suborbitals Launches Impressive Amateur Liquid Fueled Rocket

Copenhagen Suborbitals just launched their latest amateur liquid fuel rocket. Why? Because they want to strap someone to a bigger amateur liquid fuel rocket and launch them into space.

We’ve covered them before, but it’s been a while. While they make a big deal of being amateurs, they are the least amateurish amateurs we’ve come across. We’ll forgive a lot as long as they keep making great videos about their projects. Or posting great pictures of the internals of their rockets.

The Nexø I rocket they recently launched claims to be the first guided, amateur, liquid-fueled rocket. There is a nice post on the guidance system. It was launched from a custom built barge off the shore of Denmark, which allows them to escape quite a few legal hurdles around the launch. The rocket flew beautifully. That is, it went only away from the ground; no other directions. Also, it didn’t explode, which is a lot to expect from even the biggest players in the field.

Copenhagen Suborbitals continues to do amazing work. Hopefully their next rocket will be even more impressive… for amateurs, that is.

Steering High Altitude Rockets With Cold Gas

Amateur rocketry has been popular for ages, with designs ranging from small toy-scale model rockets to large-scale liquid fuel designs with steerable fins. A team out of Portland State works on some large-scale amateur rockets that can fly to very high altitudes. Since the atmosphere is thin the further the rocket flies, steering fins aren’t incredibly effective once the rockets reach high altitude. A team of students tackled this problem by designing a cold-gas reaction module to steer high-altitude rockets.

The team chose nitrogen as their cold-gas propellant, which is stored in a carbon fiber tank. After passing through a regulator, the gas is routed to several gas solenoids and then to a custom 3d-printed de Laval nozzle. An Intel Edison is used to drive the system, which calculates the rocket’s orientation with a MPU-6050. Control loops use the orientation information and fire gas through any of several nozzle ports to steer the rocket.

The system does have some limits: the solenoids are either on or off, not variable, and they aren’t incredibly fast. Even with these limitations, the team is confident that their module will work great when it embarks on its maiden flight in a brand-new custom rocket next year. The team was also awesome enough to make all of their design files open-source so you can build your own (although they warn that it’s a bit complicated and dangerous). Check out the video after the break to see a test-run of the cold-gas reaction system.

Thanks for the tip, [Nathan]!

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Apollo, the Everything Board

The best projects have a great story behind them, and the Apollo from Carbon Origins is no exception. A few years ago, the people at Carbon Origins were in school, working on a high power rocketry project.

Rocketry, of course, requires a ton of sensors in a very small and light package. The team built the precursor to Apollo, a board with a 9-axis IMU, GPS, temperature, pressure, humidity, light (UV and IR) sensors, WiFi, Bluetooth, SD card logging, a microphone, an OLED, and a trackball. This board understandably turned out to be really cool, and now it’s become the main focus of Carbon Origins.

There are more than a few ways to put together an ARM board with a bunch of sensors, and the Apollo is extremely well designed; all the LEDs are on PWM pins, as they should be, and there was a significant amount of time spent with thermal design. See that plated edge on the board? That’s for keeping the sensors cool.

The Apollo will eventually make its way to one of the crowdfunding sites, but we have no idea when that will happen. Carbon Origins is presenting at CES at the beginning of the year, so it’ll probably hit the Internet sometime around the beginning of next year. The retail price is expected to be somewhere around $200 – a little expensive, but not for what you’re getting.

Rocketduino, for high-G, high altitude logging


Although the thrill of launching rockets is usually found in their safe decent back to Earth, eventually you’re going to want some data from your flight. Everything from barometric pressure, GPS logging, and acceleration data is a useful thing to have, especially if you’re trying to perfect your craft. [zortness] over on reddit created a data logging board created especially for amateur rocketry, a fabulous piece of work that stands up to the rigors of going very fast and very high.

The design of the board is a shield for the Arduino Mega and Due, and comes with enough sensors for over-analyzing any rocket flight. The GPS logs location and altitude at 66Hz, two accelerometers measure up to 55 G. Barometric, temperature, and compass sensors tell the ground station all the data they would need to know over a ZigBee 900MHz radio link.

Because this is an Arduino, setting up flight events such as deploying the main and drogue chutes are as easy as uploading a bit of code. [zortness] built this for a 4″ diameter rocket, but he says it might fit in a 3″ rocket. We just can’t wait to see some videos of it in action.

Ask Hackaday: How about some model rocket hacks?

There’s nothing like the smell of black powder in the morning, along with the excitement and burnt propellant in the air that comes after launching a model rocket. All those 60s, 70s, 80s and 90s kids out there may remember the classes of model rocket engines – generally A, B, C, and D sized engines used to push your cardboard tube with balsa fins skyward.

A lot has changed in the world of model and amateur rocketry in the last few years. In 2009, the Tripoli Rocketry Association won a lawsuit against the Bureau of Alcohol, Tobacco, Firearms and Explosives to allow the sale of Ammonium perchlorate rocket engines to anyone. This lawsuit took almost 10 years to come to a head, but finally anyone can walk into Hobby Lobby and come out with D, E, F, and G engines in hand. Even our old favorite, Estes rockets, has gotten into the game by putting out a few awesome G-powered kits. With these off-the-shelf motors, anyone (in the US, at least) can launch a G-powered model rocket weighing under 1500 grams (3.3 lbs) without the need for a certification.

With that in mind, we’re putting out a call for model rocket hacks. If you put together an microcontroller-powered altimeter project, awesomeSend it in. On board video camera? Great! Even if you built a huge replica of the Titan IIIe (or the Estes Star Rider, a personal favorite), send that thing in. If you’re going for a huge Saturn V, the record to beat is a 1/10 scale model, so get on it.

Meet the TM65 liquid propellant rocket engine

While we’re reluctant to say it for fear of being misinterpreted, the new liquid fuel rocket engine being built by Copenhagen Suborbitals is one of the most impressive, daring, and nearly the sexiest machine we’ve ever seen. Although the engine hasn’t been fired yet, [Peter Madsen], Chief launch vehicle designer at Copenhagen Suborbitals, gives an amazing 18-minute-long rundown of the function of each and every tank and tube of the TM65 in this video.

When the TM65 engine begins its firing sequence, valves attached to tanks of alcohol and liquid Oxygen are opened. The Oxygen pours directly into an injector manifold that atomizes the liquid in the combustion chamber, while the alcohol makes a much longer trip down to the engine bell, flowing between the double wall of the chamber and nozzle for cooling. Once the alcohol and Oxygen in the combustion chamber ignite, two gigantic tanks of Helium are opened and the gas is forced down to a heat exchanger at the end of the nozzle, increasing the temperature and pressure of the Helium. The Helium is then routed to the tanks, pressurizing them and forcing fuel and oxidizer into the combustion chamber at 40 liters per second. This entire process happens in only eight seconds; after that, the rocket attached to the TM65 will be on its way upward.

We’re not going to say the TM65 is the best engine ever seen on Hackaday; we’ll leave you to decide that. We can’t wait for the video of the test fire to hit the Internet, though.