resin printed pulsejet engine in operation

A Detonation Engine Prototyped Using Resin Printing

August 29, 2022 by Dave Rowntree 5 Comments

Over the years [Integza] has blown up or melted many types of jet engine, including the humble pulsejet. Earlier improvements revolved around pumping in more fuel, or forced air intakes, but now it’s time for a bit more refinement of the idea, and he takes a sidestep towards the more controllable detonation engine. His latest experiment (video, embedded below) attempts to dial-in the concept a little more. First he built a prototype from a set of resin printed parts, with associated tubing and gas control valves, and a long acrylic tube to send the exhaust down. Control of the butane and air injection, as well as triggering of the spark-ignition, are handled by an Arduino — although he could have just used a 555 timer — driving a few solid state relays. This provided some repeatable control of the pulse rate. This is a journey towards a very interesting engine design, known as the rotating detonation engine. This will be very interesting to see, if he can get it to work.

supersonic exhaust plume from a pulsejet engine — Supersonic exhaust plume with the characteristic ‘mushroom’ shape

Detonation engines operate due to the pressure part of the general thrust equation, where the action is in the detonative combustion. Detonative combustion takes place at constant pressure, which theoretically should lead to a greater efficiency than boring old deflagration, but the risks are somewhat higher. Apparently this is tricky to achieve with a fuel/air mix, as there just isn’t enough oomph in the mixture. [Integza] did try adding a Shchelkin spiral (we call them springs around here) which acts to slow down the combustion and shorten the time taken for it to transition from deflagration to detonation.

It sort of worked, but not well enough, so running with butane and pure oxygen was the way forward. This proved the basic idea worked, and the final step was to rebuild the whole thing in metal, with CNC machined end plates and some box section clamped with a few bolts. This appeared to work reasonably well at around 10 pulses/sec with some measurable thrust, but not a lot. More work to be done we think.

We hinted at earlier work on forced-air pulsejets, so here that is. Of course, whilst we’re on the subject of pulsejets, we can’t not mention [Colinfurze] and his pulsejet go kart.

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Visual Mandela Effect: You Don’t Know Iconic Images As Well As You Think

August 29, 2022 by Kristina Panos 63 Comments

Pop quiz, hotshot: does the guy on the Monopoly box (standard edition) wear a monocle? Next question: does the Fruit of the Loom logo involve a cornucopia? And finally, does Pikachu have a black-tipped tail? If you answered yes to any of these, I am sad to say that you are wrong, wrong, wrong.

So, what’s the deal? These are all examples of the visual version of the Mandela effect (VME), which is named after the common misconception/mass false memory that anti-Apartheid activist Nelson Mandela died decades ago in prison, despite leading South Africa in the latter half of the ’90s and living until 2013. Many people even claim having seen TV coverage of his funeral, or say they learned about his death in school during Black History Month. The whole thing has VICE wondering whether CERN is causing these mass delusions somehow with the LHC.

The more attention VME gets, the more important it seems to be to study it and try to come to some conclusion. To that end, University of Chicago researchers Deepasri Prasad and Wilma A. Bainbridge submitted an interesting and quite readable study earlier this year purporting that the VME is ‘evidence for shared and specific false memories across people’. In the study, they conducted four experiments using crowd-sourced task completion services.

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Six Shooter Swaps Powder For Popped Capacitors

August 29, 2022 by Tom Nardi 43 Comments

Modern firearms might seem far removed from the revolvers of the Old West, but conceptually, they still operate on the same principle: exploding gunpowder. But as anyone who has put too much voltage through an electrolytic capacitor knows, gunpowder isn’t the only thing that explodes. (Yes, it isn’t technically an explosion.)

[Jay Bowles] wondered if it would be possible to construct an electrically-fired weapon that used used a standard capacitor in place of the primer and powder of a traditional cartridge. While it would naturally have only the fraction of the muzzle velocity or energy of even the smallest caliber firearm, it would be an interesting look at an alternate approach to what has been considered a largely solved problem since the mid-1800s.

In his latest Plasma Channel video, [Jay] walks viewers through the creation of his unconventional pistol, starting with a scientific determination of how much energy you can get out of popped capacitor. His test setup involved placing a capacitor and small projectile into an acrylic tube, and noting the relation between the speed of the projectile and the voltage passed through the cap. At 30 VDC the projectile would reliably fire from the barrel of his makeshift cannon, but by tripling the voltage to 90 VDC, he noted that the muzzle velocity saw the same 3X improvement.

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Giant 3D Printer Aims To Produce Life-Sized Boat

August 29, 2022 by Bryan Cockfield 13 Comments

As 3D printers become more ubiquitous, the number of custom designs and styles of printers has skyrocketed. From different printing materials and technologies to the movements of the printing head, we’ve seen all kinds of different takes on these tools. But one thing that has been largely limited to commercial and industrial use has been large print sizes — leaving consumer level prints to be split into several pieces to fit together later. Not so with this giant 3D printer from [Ivan], though.

The design goals for this build are to print an entire boat that [Ivan] can captain himself, and additionally an entire go kart chassis in a single piece. It’s part of a contest between him and another YouTuber and as far as we can tell he’s well on his way to completing the challenge. The printer will be able to churn through 4 kg of filament per day, and has a printable volume of 1000x1000x1420 millimeters, or just shy of 1.5 cubic meters.

While this video is just the first step of building the frame and the printer guides, we can’t wait to see the next steps in the process. It’s one of the largest 3D printers we’ve ever seen, at least outside of printers designed for building entire houses out of concrete.

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A Pi Camera To Be Proud Of

August 28, 2022 by Jenny List 16 Comments

The Raspberry Pi HQ camera has appeared in a variety of builds since its introduction back in 2020, and has brought with it many opportunities for photographic projects to compete with the professionals. The latest we’ve been sent is from [Kevin McAleer], who has taken the camera with a full-size Pi and clothed it in a case very similar to the crop of mirror-less compact cameras.

Inside the box is a Waveshare touchscreen that fits on the GPIO header, and a NanoWave 5000 mAH USB battery pack. The camera module fits on the front of the unit, with the C-mount ready to take a lens. Software is still a work in progress and is promised to be a Python script controlling the various camera programs. There are enough Pi camera projects for software to be a matter of choice and taste.

We like the form factor and we like the use of the very compact NanoWave battery, so we think this is a design with some possibilities. Perhaps a cover over the Pi ports might be of use though for general robustness in the face of everyday photography. The question remains though, whether it can come close to the performance of even a budget mirror-less compact camera, and we’re guessing that will depend as much on the operator skill, lens quality, and software capabilities as it does on the Pi HQ module. We look forward to seeing what comes of this project, but meanwhile you can see a video with all the details below the break.

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Share Screen To RGB Panel With Pi Pico W

August 28, 2022 by Danie Conradie 13 Comments

RGB LEDs are great for adding a bit of color to your life, and it’s even more satisfying to use a matrix of them as a graphic display. [bitluni] built an RGB LED display with Pi Pico to which you can share a pixelated version of your PC’s screen.

[bitluni] wanted to gain some experience with MicroPython on the Raspbery Pi Pico W, and had previously used WebSockets to transmit display data over WiFi. Unfortunately, the available MicroPython WebSockets implementation didn’t leave enough RAM for the rest of the code. Instead, he set up a simple HTTP server on the Pico that receives the pixel data as a POST request. This makes for a slow refresh rate but still looks great, especially with the 3D printed rear-projection frame.

To send display data from the computer, [bitluni] uses a simple locally hosted HTML page that takes the Pico’s IP address, and prompts you to select the display or window you want to share. It uses JavaScript to grab the display data, generate the required low-res pixel values, and send the POST request.

This looks like a fun weekend project to add to your lab or home and only costs about $20 in parts. It’s basically a scaled-down version of his giant ping pong ball wall display.

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Hackaday Links: August 28, 2022

August 28, 2022 by Dan Maloney 9 Comments

The countdown for the first step on humanity’s return to the Moon has begun. The countdown for Artemis 1 started on Saturday morning, and if all goes well, the un-crewed Orion spacecraft atop the giant Space Launch Systems (SLS) booster will liftoff from the storied Pad 39B at Cape Canaveral on Monday, August 29, at 8:33 AM EDT (1233 GMT). The mission is slated to last for about 42 days, which seems longish considering the longest manned Apollo missions only lasted around 12 days. But, without the constraint of storing enough consumables for a crew, Artemis is free to take the scenic route to the Moon, as it were. No matter what your position is on manned space exploration, it’s hard to deny that launching a rocket as big as the SLS is something to get excited about. After all, it’s been 50 years since anything remotely as powerful as the SLS has headed to space, and it’s an event that’s expected to draw 100,000 people to watch it in person. We’ll have to stick to the NASA live stream ourselves; having seen a Space Shuttle launch in person in 1990, we can’t express how much we envy anyone who gets to experience this launch up close.
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