Simple solution makes rocket fin alignment a breeze

If you’re building model rockets you want to make sure they fly straight, and most of that is dependent on the stabilizer fins. It has long been a problem come assembly time. How can you make sure that they’re being aligned without any variation? [Rrix] mentioned that one technique is to use a square to position them perfectly perpendicular to the bench on which the rocket is being assembled. But this is still prone to error. His method uses a couple of precision jigs made out of cardboard.

He designed this pair of jigs in Inkscape, then used the files to fabricate them out on a laser cutter. It worked like a charm, but led him to another issue that can be solved in a similar way. Model rockets have rail guides that travel along a rod attached to the launch pad as the craft accelerates to a point where the fins have enough effect to keep it going in a straight line. If those guides aren’t straight, your fin alignment will be all for naught. His second version of the jigs includes a cut out for these guides.

Test firing the largest amateur-built liquid fuel rocket engine

Last April, we caught wind of a very impressive rocket engine being built by Copenhagen Suborbitals. That engine was on the test pad this weekend, and the video is incredible (skip to 20:30 for the actual test). The Copenhagen Suborbitals team pulled off a successful test firing of their 65 kilo Newton alcohol and liquid Oxygen-fueled rocket.

When last we saw the TM65 engine, it was sitting on the design floor of the Copenhagen Suborbitals workspace. The plan was to fire the engine using alcohol fuel and LOX pressurized by Helium, but that plan was changed to use Nitrogen as the pressurant. The static test was an immensely successful demonstration of the engine, but unfortunately the chamber pressure (and therefore thrust) was a little low meaning the team will be moving back to Helium for the next test.

Thanks to the very successful test of the TM65, Copenhagen Suborbitals may be launching their HEAT booster later this year possibly carrying their new space capsule. Even if it’s only a crash test dummy that will make the ride into space, we can’t wait for the video of the flight.

Check out a few more (abridged) videos of the TM65 test firing after the break.

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Reminder: SpaceX launch tomorrow. Watch it live!

There isn’t a hacker out there that isn’t interested at least a little bit in the prospect of building a mission specific rocket to explode someone off the face of the planet… without killing them. We got a tiny taste of what is coming when they let us watch their engine test a few weeks ago. Tomorrow, May 19th, they are going to broadcast a launch live! You can watch it on their site beginning at 1:15 AM pacific. For some additional insight, you can also read the tweets of [Elon Musk], the founder of spaceX during the event.

Take a few minutes and enjoy the video below that discusses the program and some of the engineering obstacles they’ve had to overcome.

[via BoingBoing]

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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.

Riding rockets and jets around the frozen wastes of Sweden

An attentive reader tipped us off to the guys at Mobacken Racing (translation), a group of Swedes dedicated to the art and craft of putting jet and rocket engines on go karts and snowmobiles.

One of the simpler builds is a pulse jet sled. Pulse jets are extremely simple devices – just a few stainless steel tubes welded together and started with a leaf blower. The simplicity of a pulse jet lends itself to running very hot and very loudly; the perfect engine for putting the fear of a Norse god into the hearts of racing opponents.

Pulse jets are a bit too simple for [Johansson], so he dedicates his time towards building a jet turbine engine. Right now it’s only on a test stand, but there’s still an awesome amount of thrust coming out of that thing, as shown in the video after the break.

In our humble opinion, the most interesting build is the 1000 Newton liquid fuel rocket engine. The liquid-cooled engine guzzles NOX and methanol, and bears a striking resemblance to liquid fuel engines we’ve seen before. Sadly, there are no videos of this engine being fired (only pics of it strapped to a go-kart), but sit back and watch a couple other hilariously overpowered engines disturbing a tranquil sylvan winter after the break.

Edit: [Linus Nilsson] wrote in to tell us while the guys at Mobacken Racing are good friends, [Linus], his brother, and third guy (his words) are responsible for the pulse jet sled. The pulse jet is actually ‘valved’ and not as simple as a few stainless steel tubes. The pulse jet isn’t started by a leaf blower, either, but a four kilowatt fan. [Linus]‘ crew call themselves Svarthalet racing, and you can check out the Google translation here.

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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.