If you’ve ever thought about launching a high-altitude balloon, there’s much to consider. One of the things is how do you stream video down so that you — and others — can enjoy the fruits of your labor? You’ll find advice on that and more in a recent post from [scd31]. You’ll at least enjoy the real-time video recorded from the launch that you can see below.
The video is encoded with a Raspberry Pi 4 using H264. The MPEG-TS stream feeds down using 70 cm ham radio gear. If you are interested in this sort of thing, software, including flight and ground code, is on the Internet. There is software for the Pi, an STM32, plus the packages you’ll need for the ground side.
We love high-altitude balloons here at Hackaday. San Francisco High Altitude Ballooning (SF-HAB) launched a pair during last year’s Supercon, which attendees were able to track online. We don’t suggest you try to put a crew onboard, but there’s a long and dangerous history of people who did.
[The Slo Mo Guys] caught something fascinating while filming some firearms at 82,000 frames per second: a visible emission of light immediately preceding a bullet impact. The moment it occurs is pictured above, but if you’d like to jump directly to the point in the video where this occurs, it all starts at [8:18].
The ability to capture ultra-slow motion allows us to see things that would otherwise happen far too quickly to perceive, and there are quite a few visual spectacles in the whole video. We’ll talk a bit about what is involved, and what could be happening.
Spotting something unusual on video replay is what exteme slo-mo filming is all about.
First of all, the clear blocks being shot are ballistic gel. These dense blocks are tough, elastic, and a common sight in firearms testing because they reliably and consistently measure things like bullet deformation, fragmentation, and impact. It’s possible to make homemade ballistic gel with sufficient quantities of gelatin and water, but the clear ones like you see here are oil-based, visually clear, and more stable (they do not shrink due to evaporation).
We’ve seen the diesel effect occur in ballistic gelatin, which is most likely the result of the bullet impact vaporizing small amounts of the (oil-based) gel when the channel forms, and that vaporized material ignites due to a sudden increase in pressure as it contracts.
In the video linked above (and embedded below), there is probably a bit more in the mix. The rifles being tested are large-bore rifles, firing big cartridges with a large amount of gunpowder igniting behind each bullet. The burning powder causes a rapid expansion of hot, pressurized gasses that push the bullet down the barrel at tremendous speed. As the bullet exits, so does a jet of hot gasses. Sometimes, the last bits of burning powder are visible as a brief muzzle flash that accompanies the bullet leaving the barrel.
A large projectile traveling at supersonic velocities results in a large channel and expansion when it hits ballistic gel, but when fired at close range there are hot gasses from the muzzle and any remaining burning gunpowder in the mix, as well. All of which help generate the kind of visual spectacles we see here.
We suspect that the single frame of a flashlight-like emission of light as the flat-nosed bullet strikes the face of the gel is also the result of the diesel effect, but it’s an absolutely remarkable visual and a fascinating thing to capture on film. You can watch the whole thing just below the page break.
The escapement mechanism has been widely used for centuries in mechanical clocks. It is the mechanism by which a clock controls the release of stored energy, allowing it to advance in small, precise intervals. Not all mechanical clocks contain escapements, but it is the most common method for performing this function, usually hidden away in the clock’s internals. To some clockmakers, this is a shame, as the escapement can be an elegant and mesmerizing piece of machinery, so [Brett] brought his rolling ball escapement to the exterior of this custom clock.
The clock functions as a kitchen timer, adjustable in 10-second increments and with several preset times available. The rolling ball takes about five seconds to traverse a slightly inclined, windy path near the base of the clock, and when it reaches one side, the clock inverts the path, and the ball rolls back to its starting place in another five seconds. The original designs for this type of escapement use a weight and string similar to a traditional escapement in a normal clock. However, [Brett] has replaced that with an Arduino-controlled stepper motor. A numerical display at the bottom of the clock and a sound module that plays an alert after the timer expires rounds out the build.
Starlink has been making tremendous progress towards providing world-wide access to broadband Internet access, but there are a number of downsides to satellite-based internet such as the cluttering of low-Earth orbit, high expense, and moodiness of CEO. There are some alternatives if standard Internet access isn’t available, and one of the more ambitious is providing Internet access by balloon. Project Loon is perhaps the most famous of these (although now defunct), but it’s also possible to skip the middleman and build your own high-altitude balloon capable of connection speeds of 500 Kbps.
[Stephen] has been working on this project for a few months and while it doesn’t support a full Internet connection, the downlink on the high altitude balloon is fast enough to send high-resolution images in near-real-time. This is thanks to a Raspberry Pi Zero on board the balloon that is paired with an STM32 board which handles the radio communication on a RF4463 transceiver module. The STM32 acts as an intermediary or buffer to ensure reliable information is sent out on the radio, rather than using the Pi directly. [Stephen] also wrote a large chunk of the software responsible for handling all of these interactions, optimized for balloon flight specifically.
The blog post for this project was written a few weeks ago with a reported first launch date for the system already passed, so we will eagerly anticipate the results and the images he was able to gather using this system. Eventually [Stephen] hopes the downlink will be fast enough for video as well.Balloons are an underappreciated tool as well, and this isn’t the only way that they can be used to help send radio signals from place to place.
Working towards automating a few things in a home often seems simple on the surface, but it’s easy for these projects to snowball into dozens of sensors and various servos, switches, and cameras strewn about one’s living space. The same sort of feature creep sneaks into some of the more popular self-hosted home server platforms as well, with things like openHAB requiring so much computing power that they barely function on something like a Raspberry Pi. [Paulo] thought there should be a more lightweight way of tackling a project like this, and set about building his own smart home server with help from some interesting software.
The project is based around the Dirigera hub from Ikea, partially because [Paulo] is planning to use other smart home devices from Ikea as he can easily find them where he is, and also because these devices tend to use Zigbee, a non-proprietary communications standard. This means that if he ever wants to swap out the hub for another one in the future, it won’t be difficult to do. From here the major hurdle is that using the default software from these devices is fairly limiting, so [Paulo] reached for a Raspbee 2 Zigbee gateway for use with a Raspberry Pi and an extremely lightweight and customizable web server called Mako to make this happen. Using Lua as the high-level language to tie everything together he was able to easily deploy the server to control the Ikea hub and devices and automate them in any way he sees fit.
While it is true that software like openHAB and others already exists to do virtually any home automation task that could be imagined, if you’re looking to do something with a bare minimum of computing power something like [Paulo]’s solution is likely going to be the fastest and most reliable method of getting a few things automated around the home. If you’re looking for something completely open source and built from the ground up, though, we have seen a few alternative smart home solutions like this one which don’t rely on any proprietary hardware or software, but do take a little bit more effort on the user’s part.
Piccard inspects an instrument on his balloon (Image: Bundesarchiv, Bild 102-10382 / CC-BY-SA 3.0)
We think of human flight as a relatively modern affair, with a few claims to the first airplane all around the turn of the last century. But people flew much earlier than that by using hot air balloons as well as gas-filled ones. While the Montgolfier brothers get most of the credit for hot air ballooning in 1783, there are some reports that a Brazilian priest may have lifted himself with a balloon as early as 1709.
Regardless, we’ve had balloons a good century earlier than winged flight, if not longer. While the device is deceptively simple, it is possible to get a balloon to very high altitudes without a lot of specialized technology. Airplanes at high altitudes need a way to get enough oxygen to fuel their engines, or they have to rely on rockets. Either way, there are plenty of design and operational challenges.
Balloons, of course, can simply rise to the occasion. Auguste Piccard and an assistant took a gas-filled balloon to 15,781 meters in 1931. Their gondola was pressurized, and they were the first humans to see the curvature of the Earth and the dark sky above. That record wouldn’t stand for long, though.
CCCP-1
The Soviet Union was keenly interested in Piccard’s flight, and the Soviet Air Force set about to build a research vessel, CCCP-1 (in English, USSR-1), that flew in 1933. The envelope was a large amount of thin fabric impregnated with latex and filled with hydrogen. The air-tight gondola presented several challenges in design. Most of the science experiments were outside, of course, and in 1933, you didn’t have an Arduino and RC servos to control things.
In our previous article on Ball Grid Arrays (BGAs), we explored how to design circuit boards and how to route the signals coming out of a BGA package. But designing a board is one thing – soldering those chips onto the board is quite another. If you’ve got some experience with SMD soldering, you’ll find that any SOIC, TQFP or even QFN package can be soldered with a fine-tipped iron and a bit of practice. Not so for BGAs: we’ll need to bring out some specialized tools to solder them correctly. Today, we’ll explore how to get those chips on our board, and how to take them off again, without spending a fortune on equipment.
Tools of the Trade
For large-scale production, whether for BGA-based designs or any other kind of SMD work, reflow ovens are the tool of choice. While you can buy reflow ovens small enough to place in your workshop (or even build them yourself), they will always take up quite a bit of space. Reflow ovens are great for small-scale series production, but not so much for repairs or rework. Continue reading “Working With BGAs: Soldering, Reballing, And Rework”→
