There was a time when the very idea of building a complex circuit with the intention of destroying it would have been anathema to any electrical engineer. The work put into designing a circuit, procuring the components, and assembling it, generally with point-to-point wiring and an extravagant amount of manual labor, only to blow it up? Heresy!
But, such are the demands of national defense, and as weapons morphed into “weapon systems” after World War II, the need arose for electronics that were not only cheap enough to blow up but also tough enough to survive the often rough ride before the final bang. The short film below, simply titled “Potted and Printed Circuits“, details the state of the art in miniaturization and modularization of electronics, circa 1952. It was produced by the Telecommunications Research Establishment (TRE), the main electronics R&D entity in the UK during the war which was responsible for inventions such as radar, radio navigation, and jamming technology.
It doesn’t take long after getting a cat in your life to learn who’s really in charge. Cats do pretty much what they want to do, when they want to do it, and for exactly as long as it suits them. Any correlation with your wants and needs is strictly coincidental, and subject to change without notice, because cats.
[Alvaro Ferrán Cifuentes] almost learned this the hard way, when his cat developed a habit of exploring the countertops in his kitchen and nearly turned on the cooktop while he was away. To modulate this behavior, [Alvaro] built this AI Nerf turret gun. The business end of the system is just a gun mounted on a pan-tilt base made from 3D-printed parts and a pair of hobby servos. A webcam rides atop the gun and feeds into a PC running software that implements the YOLO3 localization algorithm. The program finds the cat, tracks its centroid, and swivels the gun to match it. If the cat stays in the no-go zone above the countertop for three seconds, he gets a dart in his general direction. [Alvaro] found that the noise of the gun tracking him was enough to send the cat scampering, proving that cats are capable of learning as long as it suits them.
With a highly publicized test firing and pledge by President Vladimir Putin that it will soon be deployed to frontline units, Russia’s Avangard hypersonic weapon has officially gone from a secretive development program to an inevitability. The first weapon of its type to enter into active service, it’s capable of delivering a payload to any spot on the planet at speeds up to Mach 27 while remaining effectively unstoppable by conventional missile defense systems because of its incredible speed and enhanced maneuverability compared to traditional intercontinental ballistic missiles (ICBMs).
In a statement made after the successful test of Avangard, which saw it hit a target approximately 6,000 kilometers (3,700 miles) from the launch site, President Putin made it clear that the evasive nature of the weapon was not to be underestimated: “The Avangard is invulnerable to intercept by any existing and prospective missile defense means of the potential adversary.” The former Soviet KGB agent turned head of state has never been one to shy away from boastful claims, but in this case it’s not just an exaggeration. While the United States and China have been working on their own hypersonic weapons which should be able to meet the capabilities of Avangard when they eventually come online, there’s still no clear deterrent for this type of weapon.
Earlier in the year, commander of U.S. Strategic Command General John Hyten testified to the Senate Armed Services Committee that the threat of retaliation was the best and perhaps only method of keeping the risk of hypersonic weapons in check: “We don’t have any defense that could deny the employment of such a weapon against us, so our response would be our deterrent force.” Essentially, the threat of hypersonic weapons may usher in a new era of “mutually assured destruction” (MAD), the Cold War era doctrine that kept either side from firing the first shot knowing they would sustain the same or greater damage from their adversary.
With President Putin claiming Avangard has already entered into serial production and will be deployed as soon as early 2019, the race is on for the United States and China to close the hypersonic gap. But exactly how far away is the rest of the world from developing an operational hypersonic weapon? Perhaps more to the point, what does “hypersonic weapon” really mean?
Imagine you’re in charge of a major heist. Right as your crew is about to rob the main vault, you need all of the electronics in the building to fail at exactly the right moment with no other collateral damage (except, maybe, to your raggedy panel van). Obviously you will turn to one of the entertainment industry’s tired tropes, the electromagnetic pulse! The only problem is that if you were to use a real one rather than a Hollywood prop either there would be practically no effect, a large crater where the vault used to be, or most of humanity would be in deep trouble. After all, the real world isn’t quite as convenient as the movies make it seem.
Our curiosity into this phenomenon was piqued when we featured an “EMP generator” from [FPS Weapons]. The device doesn’t create an enrapturing movie-esque EMP pulse suitable for taking down a casino or two, but it does spew a healthy amount of broadband electromagnetic interference (EMI) in every direction. It probably also doesn’t send the EMI very far; as we’ve seen in many other projects, it’s hard to transfer energy through the air. It got us wondering, though: what is the difference between being annoying and creating a weapon? And, is there any practical use for a device like this?
As it turns out, it’s not feasible to print an entire crossbow yet. But [Dan]’s crossbow build does a good job of leveraging what a 3D printer is good at. Most of the printed parts reside in the crossbow’s trigger group, and the diagrams in the write-up clearly show how the trigger, sear and safety all interact. Particularly nice is the automatic nature of the safety, which is engaged by drawing back the string. We also like the printed spring that keeps the quarrel in place on the bridle, and the Picatinny rail for mounting a scope. Non-printed parts include the aluminum tubes used in the stocks, and the bow itself, a composite design with fiberglass rods inside PVC pipe. The video below shows the crossbow in action, and it looks pretty powerful.
Actually, we’ll partially retract our earlier dismissal of entirely 3D-printed crossbows, but [Dan]’s version is a lot more practical and useful than this model. And for a more traditional crossbow design, check out this entirely hand-made crossbow.
While it may only be able to shoot a few cans right now, we certainly wouldn’t want to be in front of [Jason]’s fully automatic Gauss gun capable of firing 15 steel bolts from its magazine in less than two seconds.
The bolts are fired from the gun with a linear motor. [Jason] is using eight coils along the length of his barrel, each one controlled by an IGBT. These are powered by two 22 Volt 3600mAh LiPo battery packs.
As for the mechanical portion of the build, the bolts fired from this gun are actually 6.5mm nails, cut off and sharpened. These are chambered from a spring-loaded magazine, with each new bolt put into the breech with a small solenoid retracting for an instant. The frame is constructed from a square aluminum tube with additional pieces cut with a hacksaw and bent with an impromptu bench vise brake. If ever there was a person deserving of a bench top shear/brake, [Jason] is the man.
The muzzle velocity of these bolts is about 40 m/s, with a muzzle energy that’s about 3% of a .22 LR round. Not deadly, but more than enough for picking off a few cans and bottles in a garage. You can see the video of this futuristic Gauss machine gun below.
Centuries ago, craftsmen and smiths of all sort spent hundreds of hours crafting a crossbow. From the fine craftsmanship that went into making the bow to the impeccable smithing a windlass requires, a lot of effort went into building a machine of war. Since [Chris] has a 3D printer, he figured he could do just as well as these long-dead craftsmen and fabricate a crossbow in under a day.
What’s really interesting about [Chris]’ crossbow is that it is only a single piece of plastic. The bow is integrated into the stock, and the trigger works by some creative CAD design that takes advantage of the bendability of plastic. The only thing required to shoot a bolt from this crossbow is a piece of string. That, and a few chopsticks.
He won’t be taking part in any sieges, but [Chris]’ weapon is more than capable of shooting a bolt across a room or launching a balsa wood airplane. You can see an example of this after the break.