All Quiet On The West Virginia Border: The National Radio Quiet Zone

Ask a hundred people why they like to escape to the forest and you’ll probably get a hundred reasons, but chances are good that more than a few will say they seek the peace and quiet of the woods. And while the woods can be a raucous place between the wildlife and the human visitors, it is indeed a world apart from a busy city street, at least in the audio frequencies. But on the EM spectrum, most forests are nearly as noisy as your average cube farm, and that turns out to be a huge problem if you happen to run exquisitely sensitive radio receivers.  That’s the reason for the National Radio Quiet Zone, a 13,000 square mile electromagnetic safe-zone in the woods west of Washington DC. Who’s listening to what and why are a fascinating part of this story, as are the steps that are taken to keep this area as electromagnetically quiet as possible.

Continue reading “All Quiet On The West Virginia Border: The National Radio Quiet Zone”

Tales Of Garage Design: Achieving Precision From Imprecise Parts

Designing parts to fit perfectly together is hard. Whether it’s the coarseness of our fabrication tools or the procedures of the vendor who makes our parts, parts are rarely the exact dimension that we wish they were. Sadly, this is the penalty that we pay by living in a real world: none of our procedures (or even our measurement tools!) are perfect. In a world of imperfect parts, imperfect procedures, and imperfect measurement techniques, how on earth are we supposed to build anything that works? Fortunately, we’re in luck! From the brooding minds of past engineers, comes a suite of design techniques that can combat the imperfections of living in an erroneous world.

Continue reading “Tales Of Garage Design: Achieving Precision From Imprecise Parts”

Flying The Infinite Improbability Drive

Not since the cold fusion confusion of 1989 has the pop science media industry had a story like the EmDrive. The EmDrive is a propellantless thruster – a device that turns RF energy into force. If it works, it will revolutionize any technology that moves. Unlike rocket motors that use chemicals, cold gas, ions, or plasma, a spacecraft equipped with an EmDrive can cruise around the solar system using only solar panels. If it works, it will violate the known laws of physics.

After being tested in several laboratories around the world, including Eagleworks, NASA’s Advanced Propulsion Physics Laboratory, the concept of a device that produces thrust from only electricity is still not disproven, ridiculed, and ignored. For a device that violates the law of conservation of momentum, this is remarkable. Peer review of several experiments are ongoing, but [Paul] has a much more sensational idea: he’s building an EmDrive that will propel a cubesat.

Make no mistake, our current understanding of the universe is completely incompatible with the EmDrive. The idea of an engine that dumps microwave energy into a metal cone and somehow produce thrust is on the fringes of science. No sane academic physicist would pursue this line of research, and the mere supposition that the EmDrive might work is irresponsible. Until further peer-reviewed experiments are published, the EmDrive is the fanciful dream of a madman. That said, if it does work, we get helicarriers. Four EmDrives mounted to a Tesla Roadster would make a hovercar. Your grandchildren would only see Earth’s sun as a tiny speck in the night sky.

This isn’t [Paul]’s first attempt to create a working propellantless thruster. For last year’s Hackaday Prize, [Paul] built a baby EmDrive. Unlike every other EmDrive experiment that used 2.4GHz microwaves, [Paul] designed his engine to operate on 22 to 26 GHz. This means [Paul]’s is significantly smaller and can easily fit into a cubesat. If it works, this cubesat will be able to maintain its orbit indefinitely, fly to the moon and back, or go anywhere in the solar system provided the solar panels get enough light.

While [Paul]’s motivations in creating a citizen science version of the EmDrive are laudable, Hackaday.io’s own baby EmDrive does not display the requisite scientific rigor for a project of this magnitude. Experimental setups are ill-defined, graph axes are unlabeled, and there is not enough information to properly critique [Paul]’s baby EmDrive experiments.

That said, we can’t blame a guy for trying, and the EmDrive is still an active area of research with several papers under peer review. [Paul]’s plan of putting an EmDrive into orbit is putting the cart several miles ahead of the horse, but it is still a very cool project for this year’s Hackaday Prize.

The HackadayPrize2016 is Sponsored by:

A $1000 Tiny Personal Satellite

If you ever read any old magazines, you might be surprised at how inexpensive things used to be. A U.S. postage stamp was six cents, a gallon of gas was $0.34, and the same amount of milk was $1.07. Everything is relative, though. The average household income back then was under $8,000 a year (compared to over $53,000 a year in 2014). So as a percentage of income, that milk actually cost about seven bucks.

The same is true of getting into orbit. Typical costs today just to get something into orbit has gone from–no pun intended–astronomical, to pretty reasonable. Lifting a pound of mass on the Space Shuttle cost about $10,000. On an Atlas V, it costs about $6,000. A Falcon Heavy (when it launches) will drop the cost to around $1,000 or so. Of course, that’s just the launch costs. You still have to pay for whatever you want to put up there. Developing a satellite can be expensive. Very expensive.

Continue reading “A $1000 Tiny Personal Satellite”

Hacklet 98 – Underwater ROVs

A few motors, propellers, a camera, maybe a wire tether, and some waterproof electronics. Throw it all together and baby you’ve got an underwater Remotely Operated Vehicle (ROV) cooking! It all sounds simple on the surface, but underwater ROVs are a tough challenge. We’ve all seen deep-sea ROVs searching the wreck of the Titanic, or working to stop the flow of oil below the Deepwater Horizon. Plenty of hackers, makers, and engineers have been inspired to build their own underwater ROVs. This week on the Hacklet, we’re spotlighting at some of the best ROV projects on Hackaday.io!

borgcubeWe start with [Tim Wilkinson] and BorgCube ROV. [Tim] has jumped into the world of underwater ROVs with both feet. BorgCube is designed to operate in the unforgiving salt waters of the Pacific Ocean. This ROV can see in stereo, as [Tim] plans to use a head mounted VR display like the Oculus Rift to control it. [Tim] wanted to use a Raspberry Pi as the brains of this robot. Since the Pi Compute module can handle two cameras, it was a natural fit. The electronic speed controls are all low-cost Hobby King R/C car units. [Tim] created a custom circuit board to hold all 12 ESCs. This modular design allows individual controllers to be swapped out if one meets an untimely doom. BorgCube is just getting wet, but with 37 project logs and counting, we’re sure [Tim] will keep us posted on all the latest action!

 

lunaNext up is [MrCullDog] with Luna I ROV. Inspired by a professional underwater ROV, [MrCullDog] decided to build a deep diving unmanned vehicle of his very own. Like BorgCube above, many of Luna I’s motors and drive components come from radio controlled hobby electronics. [MrCullDog] is bringing some 3D printed parts into the mix as well. He’s already shown off some incredibly well modeled and printed thruster mounts and ducts. The brains of this robot will be an Arduino. Control is via wired Ethernet tether. [MrCullDog] is just getting started on this project, so click the follow button to see updates in your Hackaday.io Feed.

cavepearlNext up is [Edward Mallon] with The Cave Pearl Project. Not every underwater system needs motors – or even a human watching over it. The Cave Pearl Project is a series of long duration underwater data loggers which measure sea conditions like temperature and water flow. [Edward’s] goal is to have a device which can run for a year on just three AA batteries. An Arduino Pro Mini captures data from the sensors, time stamps it, and stores it to a micro SD card. If the PVC pipe enclosure keeps everything dry, the data will be waiting for [Edward] to collect months later. [Edward] isn’t just testing in a swimming pool, he’s been refining his designs in open water for a couple of years now.

 

If you want to see more under (and above) water projects, check out our updated waterborne projects list! If I missed your project, don’t be shy! Just drop me a message on Hackaday.io. That’s it for this week’s Hacklet. As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!

Materials To Know: Acetal And Delrin

Delrin, Acetal, and its many trade names is a material properly known as Polyoxymethylene or POM. It is one of the strongest plastics and is a good go-to material when you want the best properties of plastic, and don’t need the full strength of a metal part. It was originally formulated to compete with Zinc and Aluminum castings after all.

I won’t go too deep into the numbers behind POM. If you need the Young’s Modulus, you probably don’t need this guide. This is intended to be more of a guide to its general properties. When you’re looking for something to fit an application it is usually easier to shift through the surface properties to select a few candidates, and then break the calculator out later to make sure it will work if you’re uncertain about the factor of safety.

The most popular property of POM is its ease of machining. While doing this research every single site I came across referred to it as the most machinable plastic. That’s about as objective as subjective praise can get. It doesn’t tend to grab tools like, for example, HDPE. It also chips nicely unlike UHMW and Nylon. Some plastics, like UHMW, have the unfortunate tendency to render the dials on a mill or lathe meaningless as the plastic deflects away from the tool. POM does not do this as much. Of course these other plastics have their strengths as well, but if any plastic will do, and you’re machining, POM is a very good choice.

Continue reading “Materials To Know: Acetal And Delrin”

Oak Lamp Glows Bright

Looking for a way to spruce up your place with a touch of rustic-future-deco? Why not embed LEDs somewhere they were never designed for? [Callosciurini] had a nice chunk of oak and decided to turn it into a lamp.

He was inspired by a similar lamp that retails for over $1,000, so he figured he would make his own instead (business idea people?). The oak is a solid chunk measuring 40x40x45cm and what he did was route out an angled channel across all faces of the cube. This allowed him to installed a simple LED strip inside the groove — then he filled it with an epoxy/paint mix to give it that milky glow.

To finish it off he sanded the entire thing multiple times, oiled the wood, and sanded it again with a very fine grit. The result is pretty awesome.

Now imagine what you could do design-wise if you could fold wood to make a lamp? Well with this custom wood-folding saw-blade, the sky is the limit!

[via r/DIY]