In Space, No One Can Hear You Explode: The Byford Dolphin Incident

February 15, 2019 by Al Williams 47 Comments

“It wouldn’t happen that way in real life.” One of the most annoying habits of people really into the “sci” of sci-fi is nitpicking scientific inaccuracies in movies. The truth is, some things just make movies better, even if they are wrong.

What would Star Wars be without the sounds of an epic battle in space where there should be no sound? But there are plenty of other examples where things are wrong and it would have been just as easy to get them right — the direction of space debris in the movie Gravity, for example. But what about the age-old trope of explosive decompression? Some movies show gross body parts flying everywhere. Others show distressed space travelers surviving in space for at least brief periods.

It turns out, dropping pressure from one atmosphere to near zero is not really good for you as you might expect. But it isn’t enough to just make you pop like some meat balloon. You are much more likely to die from a pulmonary embolism or simple suffocation. But you are a meat balloon if you experience a much greater change in pressure. How do we know? It isn’t theoretical. These things have happened in real life.

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Supercon 2018: Mike Szczys And The State Of The Hackaday

February 14, 2019 by Elliot Williams 12 Comments

Every year at Superconference, Editor-in-Chief Mike Szczys gets the chance to talk about what we think are the biggest, most important themes in the Hackaday universe. This year’s talk was about science and technology, and more importantly who gets to be involved in building the future. Spoiler: all of us! Hackaday has always stood for the ideal that you, yes you, should be taking stuff apart, improving it, and finding innovative ways to use, make, and improve. To steal one of Mike’s lines: “Hackaday is an engine of engagement in engineering fields.”

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Hack My House: Garage Door Cryptography Meets Raspberry Pi

February 13, 2019 by Jonathan Bennett 57 Comments

Today’s story is one of victory and defeat, of mystery and adventure… It’s time to automate the garage door. Connecting the garage door to the internet was a must on my list of smart home features. Our opener has internet connection capabilities built-in. As you might guess, I’m very skeptical of connecting a device to the internet when I have no control over the software running on it.

The garage door is controlled by a button hung on the garage wall. There is only a pair of wires, so a simple relay should be all that is needed to simulate the button press from a Raspberry Pi. I wired a relay module to a GPIO on the Pi mounted in the garage ceiling, and wrote a quick and dirty test program in Python. Sure enough, the little relay was clicking happily– but the garage door wasn’t budging. Time to troubleshoot. Does the push button still work? *raises the garage door* yep. How about the relay now? *click…click* nope.

You may have figured out by now, but this garage door opener isn’t just a simple momentary contact push button. Yes, that’s a microcontroller, in a garage door button. This sort of scenario calls for forensic equipment more capable than a simple multimeter, and so I turned to Amazon for a USB oscilloscope that could do some limited signal analysis. A device with Linux support was a must, and Pico Technology fit the bill nicely.

Searching for a Secret We Don’t Actually Need

My 2 channel Picotech oscilloscope, the 2204A, finally arrived, and it was time to see what sort of alien technology was in this garage door opener. There are two leads to the button, a ground and a five volt line. When the button is pressed, the microcontroller sends data back over that line by pulling the 5 V line to ground. If this isn’t an implementation of Dallas 1-wire, it’s a very similar concept.

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The “Impossible” Tech Behind SpaceX’s New Engine

February 13, 2019 by Tom Nardi 92 Comments

Followers of the Church of Elon will no doubt already be aware of SpaceX’s latest technical triumph: the test firing of the first full-scale Raptor engine. Of course, it was hardly a secret. As he often does, Elon has been “leaking” behind the scenes information, pictures, and even video of the event on his Twitter account. Combined with the relative transparency of SpaceX to begin with, this gives us an exceptionally clear look at how literal rocket science is performed at the Hawthorne, California based company.

This openness has been a key part of SpaceX’s popularity on the Internet (that, and the big rockets), but its been especially illuminating in regards to the Raptor. The technology behind this next generation engine, known as “full-flow staged combustion” has for decades been considered all but impossible by the traditional aerospace players. Despite extensive research into the technology by the Soviet Union and the United States, no engine utilizing this complex combustion system has even been flown. Yet, just six years after Elon announced SpaceX was designing the Raptor, they’ve completed their first flight-ready engine.

The full-flow staged combustion engine is often considered the “Holy Grail” of rocketry, as it promises to extract the most possible energy from its liquid propellants. In a field where every ounce is important, being able to squeeze even a few percent more thrust out of the vehicle is worth fighting for. Especially if, like SpaceX, you’re planning on putting these new full-flow engines into the world’s largest operational booster rocket and spacecraft.

But what makes full-flow staged combustion more efficient, and why has it been so difficult to build an engine that utilizes it? To understand that, we’ll need to first take a closer look at more traditional rocket engines, and the design paradigms which have defined them since the very beginning.

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Love Songs To The Microphone

February 12, 2019 by Al Williams 3 Comments

A biographer of Frank Sinatra once commented that for singers like Sinatra, their instrument is the microphone. We tend to think of microphones as ideal transducers, picking up sound faithfully. But like most electronic components, microphones are imperfect. They have a varying frequency response. They pick up popping noises when we say words like “popcorn” that are normally lost to someone listening live.

[Cheddar] has an interesting video (see below) that covers how performers like Sinatra, Bing Crosby, and Billie Holiday learned to use the microphone to their advantage. They suggest that the microphone changed the way humans sing, and they are right.

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EF50: The Tube That Changed Everything

February 12, 2019 by Al Williams 32 Comments

From today’s perspective, vacuum tubes are pretty low tech. But for a while they were the pinnacle of high tech, and heavy research followed the promise shown by early vacuum tubes in transmission and computing. Indeed, as time progressed, tubes became very sophisticated and difficult to manufacture. After all, they were as ubiquitous as ICs are today, so it is hardly surprising that they got a lot of R&D.

Prior to 1938, for example, tubes were built as if they were light bulbs. As the demands on them grew more sophisticated, the traditional light bulb design wasn’t sufficient. For one, the wire leads’ parasitic inductance and capacitance would limit the use of the tube in high-frequency applications. Even the time it took electrons to get from one part of the tube to another was a bottleneck.

There were several attempts to speed tubes up, including RCA’s acorn tubes, lighthouse tubes, and Telefunken’s Stahlröhre designs. These generally tried to keep leads short and tubes small. The Philips company started attacking the problem in 1934 because they were anticipating demand for television receivers that would operate at higher frequencies.

Dr. Hans Jonker was the primary developer of the proposed solution and published his design in an internal technical note describing an all-glass tube that was easier to manufacture than other solutions. Now all they needed was an actual application. While they initially thought the killer app would be television, the E50 would end up helping the Allies win the war.

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Security Engineering: Inside The Scooter Startups

February 12, 2019 by Brian Benchoff 62 Comments

A year ago, ridesharing scooter startups were gearing up for launch. Workers at Bird, Lime, Skip, and Spin were busy improving their app, retrofitting scooters, and most importantly, figuring out the logistics of distributing thousands of electronic scooters along the sidewalks of the Bay Area. These companies were gearing up for a launch in early summer, but one company — nobody can remember exactly who — decided to launch early. First mover advantage, and all. Overnight, these scooter companies burst into overdrive, chucking scooters out of panel vans onto the sidewalk simply to keep up with the competition.

The thing about San Francisco, and California in general, is that it’s a very direct democracy masquerading as a representative government. Yes, there are city council members and a state legislature, but the will of the people will rule. No one liked tripping over the scooters littering the sidewalks, so the scooters ended up at the bottom of a lake. Or in trees. Or in the trash. In time, city permits were issued, just like a hot dog cart or any other business operating on a public sidewalk, and the piles of electric scooters disappeared. Not before hundreds of scooters were vandalized, that is.

It’s still early in the electric scooter rental startup space, but if there’s one company leading the pack, It’s Bird. they’re getting the most press, the CEO was formerly at Lyft and Uber (which explains the press), and they’ve raised nearly a half Billion dollars in funding (which explains the press). Bird is valued at two Billion dollars, and it’s one of four major ridesharing scooter startups. Pets.com had nothing on this.

Despite how overvalued you think a scooter startup might be, they’re still a business, and they’re ruled by the bottom line. Bird has grown a lot in the past year, and with that comes engineering challenges. The Bird scooters must be more resistant to vandalism. The Bird scooters must be harder to steal. Above all else, they must remain in service longer. This is the teardown of how Bird managed to improve their bottom line and engineer a better scooter.

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