Steering High Altitude Rockets With Cold Gas

June 20, 2015 by Ethan Zonca 23 Comments

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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Give Me A Welder And Rod Stock And I’ll Build You The World

June 11, 2015 by Mike Szczys 27 Comments

Metal fabrication is a an art that often goes under appreciated. The ability to take common stock in the form of sheet, pipe (square or round), and in this case rod, and make it into anything is intoxicating for the artist and super villain inside of each of us. Recently [asciiArtVandaly] took on an interesting job and was thoughtful enough to make a photo album of the process. He literally created the world out of metal.

The build is a wire-frame globe. The latitude and longitude rods are rolled to the proper arc, but holding them in place is a bit of a trick. This image shows the welding jig built just for this project. It has large and small nobs to match the increasing spacing of the rods, with washers holding down ever other joint. If you want to see an example of rod-rolling check out the unrelated How It’s Made segment found after the break.

This jig is visually stunning to look at, but the math used to lay something like this out is only mildly interesting compared to the work done to add the continents to the piece. Each of these were cut out and then hand hammered to match the curve of the globe before being welded in place and outfitted with lighting for cities. That’s a skill you can’t get without a lot of practice — and get this, [asciiArtVandalay] does it as a hobby. Who knew robot engineers needed hobbies?

The finished globe is about eighty pounds of stainless steel. The build ends up being corporate art for a company sure to turn [Tyler Durden’s] eye.

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Quadrotor Control Systems And Kerbal Harriers

June 10, 2015 by Brian Benchoff 19 Comments

Kerbal Space Program, the game that teaches engineers at JPL and SpaceX the basics of rocket design and orbital mechanics, recently had a giant update. There are now science contracts that require you to fly Kerbals all over their tiny globe, collect data, and transmit it back to the Kerbal Space Center. As would be expected, this is a grind for XP, and the contracts sometimes don’t make sense – you need to collect data from cliff faces and mountain tops. Landing a Kerbal jet at these places is hard.

[Matt Thiffault] wanted to do these science contracts more efficiently. The best way to get to a remote location without a landing strip would be a helicopter, but a harrier jump jet would do just as well. This isn’t supported in the stock game, so [Matt] wrote a complete control system for four engines to control a hovering Kerbal jet.

[Matt]’s work is built on kOS, a scriptable autopilot mod for Kerbal that was originally intended to be something like the Apollo Guidance Computer. People have been using it to make computerized skycranes and automated rendezvous and docking programs, but these are actually relatively simple examples; there’s far more math involved in flying a quadcopter than there is getting into orbit.

To build his automated hovering harrier, [Matt] needed an aircraft. His Kerrier has parts from the Kerbal Aircraft Expansion, B9, and Infernal Robotics mods for KSP, but this is only half the problem. Anyone can put four tilt jets on an airplane, and it takes a real wizard to force a control system to hover. Hover control of the Kerbal harrier is accomplished with a complete control system for a four-engined aircraft, with proper PID control loops and code updating at 20Hz.

With kOS, the proper plane, and the right software running on this emulated guidance computer, [Matt] is able to park his plane in mid-air, have a Kerbal descend the ladder, perform some science, and return to base. It’s an impressive amount of work for a video game. A good thing, too: [Matt] is looking to get into controls engineering professionally. Whether this will go on his resume is another question entirely.

Subwoofer Vortex Cannon: 300V Of “Thwup!”

June 8, 2015 by Elliot Williams 20 Comments

Need a cool toy for your kids? How about something with a bunch of fun fluid dynamics and a tinge of higher-than-average-voltage danger? Did we mention the subwoofer and bank of high-voltage capacitors? Have we got the project for you: [Robert Hart]’s vortex cannon design.

We’ve seen vortex cannons before, where you usually fix a balloon to the back of a trash can. Pull on the balloon membrane and then let it go with a snap, and it sends out a swirling donut of high-pressure air that travels surprisingly far. It’s like smoke rings, but amped up a bit.

[Robert]’s addition is to bolt on a high-power subwoofer in place of the balloon’s rubber membrane, and generate the air pulse by dumping a capacitor bank into the speaker.

The circuit design is a bit more clever than we thought at first. The bottom half is a voltage inverter followed by a diode bridge rectifier that essentially makes 320V DC (peak) out of 12V, and stores this in four fairly large capacitors. A pushbutton activates a relay that dumps the capacitors through the speaker.

On top of the circuit is a -12V voltage inverter. Just before firing, the speaker is pulled back a little bit by applying this -12V to the speaker, and then the relay is triggered and the capacitors dump, shooting the speaker cone forward.

[Robert] is still developing and testing the device out, so if you’re curious or just want to say hi, head on over to Hackaday.io and do so! Be sure to check out his videos. The smoke tests are starting to look good, and we love the control box and high-voltage warning stickers.

“Giger Counter” Makes Radiation Detection Surreal

June 8, 2015 by Theodora Fabio 14 Comments

Here’s a quick question: are Geiger and Giger (as in H.R. Giger, designer of the Alien Xenomorph) pronounced the same? The answer is no. Nevertheless, the late artist has had his name mispronounced (for the record, it’s ghee-gur) by many over the years. [Steve DeGroof’s] friend posted a goofy tweet that gave him the inspiration to finally put a skeletal lid on the matter, the Giger Counter.

The innards are a Mightyohm Geiger Counter Kit. The external casing is where the true hack lies in this project, made from a 1:2 scale plastic skeleton model, flexible conduit, and dark metallic spray paint. Only the ribcage, some vertebrae, and part of the skull are used from the model. They are assembled in a delightfully inhuman fashion with some conduit wrapped around it and into the bottom of the ribcage for good measure. After some gluing and spray painting, the LED from the Geiger Counter kit is placed through a drilled hole in the skull while the board sits inside the ribcage. Getting the board in and out can be a little tricky, but it looks like the batteries can be changed without having to pull the whole board out.

Check out the video below to see the Giger Counter. If you want another hack inspired by H.R. Giger’s artistic vision, take a look at this Xenomorph suit we covered. Or, if you can’t get enough Geiger counters, we’ve featured plenty of cool ones on this site.

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Nice Looking Countdown Timer For The Home Game Show Enthusiast

June 5, 2015 by Rich Bremer 12 Comments

Every couple of weeks, [Roo’s] place of employment, TMW Unlimited, has a contest. This contest takes place in the form of a game show and the contestants have 30 seconds to pitch their current project to the group. A panel of judges vote on the best pitches. Winners receive cupcakes and drinks. Originally, stopwatches were used to keep track of the elapsed time, however, a stopwatch is not very game showy. [Roo] set out to make a countdown timer to add some authenticity to the bi-weekly event.

The main enclosure is a plastic fence post. Fifteen holes and 15 large LEDs are covered up by large plastic translucent spheres. End caps were designed and 3D printed to not only make the rig look good but also to serve as a speaker mount. Inside resides an Arduino that does the counting and turns off the row of lights, one every 2 seconds, as the countdown continues. A speaker not only ticks and tocks its way down with the lights, it also buzzes when time is up. Starting and resetting the timer is as easy as pushing a single button mounted on the case.

If you’ve already built a game show timer, you may want to check out this DIY game buzzer system!

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Jacquard Loom Becomes A Display

June 4, 2015 by Brian Benchoff 3 Comments

The world’s leading expert on mechanical computers wasn’t [Charles Babbage]; sure, he could design stuff, but eventually you need to actually build something. We are now graced with the expertise of [Chris Fenton]. He’s built mechanical calculators, a mechanical digital computer, and now a mechanical display inspired by the Jacquard loom.

[Chris] calls his creation the PixelWeaver, and the name isn’t far from the truth; it’s a 32-hook Jacquard style punch card reader that could be mounted over a small loom. Instead of weaving rugs and fabric, the PixelWeaver controls a 6×5 black and white display.

The PixelWeaver is built out of t-slot aluminum, 3D printed parts, and a web of thread to transfer motion from rotating cams to ratchets and pixels. The display itself is heavily inspired by a Lego mechanical display, and the cards that store the data for the display are laser-cut plywood. Interestingly, there’s nothing in this machine that couldn’t have been made 150 years ago; it’s the same technology used to weave rugs, although the necessity of a bitmap display in the Victorian era is a bit questionable.

You can see a few videos of the PixelWeaver below. If you’re wondering what else has come out of [Chris]’ mechanical computing lab, check out his digital computer and Fibonacci calculating set of gears. For a real treat, here’s a machine that will calculate all primes under 1000 in 30 years.

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