Chocolate as rocket fuel

[Adric Menning] has an unfortunate allergy. He’s allergic to chocolate. Instead of eating the stuff, he’s using it to build model rocket engines. The project stems from the Quelab Hackerspace’s chocolate hacking challenge which spawned a number of interesting hacks. [Adric’s] doesn’t use pure chocolate (an experiment with a Hershey’s bar was a bust) but manages to ignite using a Milky Way bar.

This is not as unorthodox as you might think. Sugar and potassium nitrate have long been used to create solid rocket propellant. The chocolate version is swapping out plain old sugar for the candy bar. It was chopped into 10 gram chunks to make proportion calculations easier later on. The chunks go into the freezer to make them easier to grind using a mortar and pestle. Once it’s a somewhat chunk-free powder he mixes it with the potassium nitrate which previously had its own trip through the grinder. After being packed into a chunk of PVC pipe and fitted with an exhaust nozzle the engine is ready to go.

You can check out the test-fire video after the break. There’s a burn restriction in his area due to drought so this is just an engine test and not an actual rocket launch.

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Matchstick model rocketry

[Valentin] is the MacGyver of model rocketry, building a small rocket out of three items many people have hanging around the house. Cat litter, matchsticks, and a ballpoint pen are the raw materials that he rounded up before setting to work on the build.

The housing of the ballpoint pen will act as the body of the rocket. [Valentin] stuffed the tip of the pen with cat litter, creating the first part of the fuel chamber. Next, the heads of the matches were very carefully muddled into a fine powder which fills the bulk of the pen housing. Finish this off with another plug of cat litter and you’re almost done. The final step is to drill a hole through the plug layer at the tip of the pen, creating a nozzle to focus the force as the fuel burns.

From the videos we’d say there needs to be some work done as far as rocket guidance, but the solid state fuel certainly does work. Just remember to make your personal safety the first priority when working with combustibles like this!

Wondering how to launch something like this? Here’s a way to make your own igniters.

Amazing backyard rocket ship tree house

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If you thought you had a cool tree house as a kid, think again. Tasked with landscaping his back yard and building a tree house for his son, [Jon] decided to go all out and build him a rocket ship instead.

Rising 15 feet into the Seattle skyline, the tree house known as the Ravenna Ultra-Low-Altitude Vehicle (RULAV), is sure to be the envy of every kid in the neighborhood. [Jon] and a friend worked for well over a year on their creation, welding, grinding, painting, and riveting their way along. After the structure was built, they fabricated some custom PCBs, using them to build the ship’s 14 control panels. The entire operation is controlled by a custom OS built to run on the three ATmega MCUs that manage operations.

Not content with just a handful of knobs and switches, the ship contains over 800 LEDs among its laundry list of electronics goodies. Compressed air is used to shoot water from positioning “thrusters”, while a paint mixer spins under the ship to simulate the rough and bumpy nature of space travel. The simulated launches are capped off with plenty of authentic NASA-style audio and a sub woofer that gives everything a deep, resonating rumble.

The project is truly amazing, and a ton of work went into every little detail in order to make this the most spectacular tree house ever seen. [Jon] definitely takes the award for “Coolest Dad Ever” for this build, even we’re jealous!

The pictures certainly don’t do it justice, so be sure to check out the video below for a quick introduction and demo of this awesome project.

Thanks to [Jeremy Elson] for the tip.

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Model rocket radio telemetry

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[Ken] sent us his Instructable in which he used radio telemetry to monitor the status of his air-powered model rocket through a series of launches. His setup is centered around an Arduino IDE-compatible board that looks to be about the size of a Boarduino, but has the benefit of an embedded 915 MHz radio module. The vendor he used also sells a good handful of add-on modules which he used for his in-flight recording, including a barometric pressure monitor and a 3-axis accelerometer. During flight, the rocket constantly sends data to a base station, provided it stays within radio operating range.

For is initial tests, [Ken] launched his rocket four times, getting usable data on half of them. He found out some interesting things about his model rocket, including the fact that it creates a maximum launch force of 60 Gs. He has plans to revise his setup in the future, such as lightening the battery load as well as adding a high-G analog sensor for recording the forces at take off. This kit, or a more reasonably priced clone, would make for a great addition to any rocket buff’s inventory.

Attitude control for a really big rocket

If this is meant for a model rocket it must be the biggest we’ve ever seen. [Scott] and [Trevor] took on the task of building a rocket attitude control system after reading about some research on the topic. But that researcher only tested the theories using simulations so they set out to build their own. The prototype above has a tank of compressed Nitrogen which can hold up to 3000 PSI. You can begin to understand why this needs to be used with a big rocket. The pressurized gas is connected through a regulator to four valves which feed nozzles around the circumference of the fuselage. An Arduino takes readings from a gyroscope and actuates the gas valves via a relay board.

You can check out the test rig in the video after the break. The prototype is suspended horizontally from a wire and its orientation held at one position by the system. There’s also a paper (PDF) if you’re interested in the equations that went into the stabilization control. This system would have been right at home on that huge sugar rocket we saw back in October.

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Oxyhydrogen water rocket

[cmwslw] built a soda-bottle water rocket that uses the ignition of oxyhydrogen gas to quickly expel the water, as opposed to the usual compressed air and water mixture. His project contains excellent documentation with photos and it builds on other articles he’s written about generating the flammable HHO gas used to launch his craft into the skies. Every aspect of this project uses items most of us have at home or could score cheaply at most hardware stores.

We love seeing projects that re-purpose everyday materials into something fun. Just be sure to dodge the missile pop bottle as it speeds back to Earth!

Making model rocket motor igniters

[Stephan Jones] has an easy method for making your own model rocket engine igniter. The solid state motors used in this hobby consume one igniter with each electrically triggered launch. Whether you’re making your own motors or not, this construction technique should prohibit you from every buying an igniter again. The process involves bending some nichrome wire around a paper clip, adding some structural support to the leads using masking tape, and insulating the business end with a quick dip in paint.

Now would be a good time to send us your launchpad hacks. All we’ve seen so far is a launchpad for water rockets.

[via Make]