Although not the first to try and build a DIY solar-powered remote control airplane, [ProjectAir]’s recent attempt is the most significant one in recent memory. It follows [rctestflight]’s multi-year saga with its v4 revision in 2019, as well as 2022’s rather big one by [Bearospace]. With so many examples to look at, building a solar-powered RC airplane in 2024 should be a snap, surely?
The first handicap was that [ProjectAir] is based in the UK, which means dealing with the famously sunny weather in those regions. The next issue was that the expensive, 20% efficient solar panels are exceedingly fragile, so the hope was that hot-gluing them to the foam of the airplane would keep them safe, even in the case of a crash. During the first test flights they quickly found that although the airplane few fairly well, the moment the sun vanished behind another cloud, the airplane would quite literally fall out of the sky, damaging some cells in the process.
Many have sought the holy grail of making commercial media both readable and copy-proof, especially once everyone began to copy those floppies. One of these attempts to make floppies copy-proof was Softguard’s Superlok. This in-depth look at this copy protection system by [GloriousCow] comes on the heels of a part one that covers Formaster’s Copy-Lock. Interestingly, Sierra switched from Copy-Lock to Superlok for their DOS version of games like King’s Quest, following the industry’s quest in search of this holy grail.
The way that Superlok works is that it loads a (hidden) executable called CPC.COM which proceeds to read the 128 byte key that is stored on a special track 6. With this key the game’s executable is decoded and fun can commence. Without a valid ‘Play’ disk containing the special track and CPC.COM executable all one is instead left with is a request by the game to ‘insert your ORIGINAL disk 1’.
Sierra’s King Quest v1.0 for DOS.
As one can see in the Norton Commander screenshot of a Sierra game disk, the hidden file is easily uncovered in any application that supports showing hidden files. However, CPC.COM couldn’t be executed directly; it needs to be executed from a memory buffer and passed the correct stack parameters. Sierra likely put in very little effort when implementing Softguard’s solution in their products, as Superlok supports changing the encryption key offset and other ways to make life hard for crackers.
Sierra was using version 2.3 of Superlok, but Softguard would also make a version 3.0. This is quite similar to 2.x, but has a gotcha in that it reads across the track index for the outer sector. This requires track wrapping to be implemented. Far from this kind of copy protection cracking being a recent thing, there was a thriving market for products that would circumvent these protections, all the way up to Central Point’s Copy II PC Option Board that would man-in-the-middle between the floppy disk drive and the CPU, intercepting data and render those copy protections pointless.
As for the fate of Softguard, by the end of the 1980s many of its customers were tiring of the cat-and-mouse game between crackers and Softguard, along with issues reported by legitimate users. Customers like Infographics Inc. dropped the Superlok protection by 1987 and by 1992 Softguard was out of business.
While plastics are very useful on their own, they can be much stronger when reinforced and mixed with a range of fibers. Not surprisingly, this includes the thermoplastic polymers which are commonly used with FDM 3D printing, such as polylactic acid (PLA) and polyamide (PA, also known as nylon). Although the most well-known fibers used for this purpose are probably glass fiber (GF) and carbon fiber (CF), these come with a range of issues, including their high abrasiveness when printing and potential carcinogenic properties in the case of carbon fiber.
So what other reinforcing fiber options are there? As it turns out, cellulose is one of these, along with basalt. The former has received a lot of attention currently, as the addition of cellulose and similar elements to thermopolymers such as PLA can create so-called biocomposites that create plastics without the brittleness of PLA, while also being made fully out of plant-based materials.
Regardless of the chosen composite, the goal is to enhance the properties of the base polymer matrix with the reinforcement material. Is cellulose the best material here?
The European Space Agency (ESA) is showing 3D-printed metal parts made onboard the International Space Station using a printer and materials the agency sent earlier this year. While 3D printing onboard the ISS is nothing new, the printing of metal parts in space is an important advancement. The agency’s goals are to be able to produce more tools and spares in situ rather than having to rely on resupply missions. An ambitious idea being pitched is to use captured space debris as input as well, which would further decrease the ISS’s dependence on Earth and expensive cargo runs from the bottom of the gravity well.
Recently, [Richard Audette] bought an Akaso EK7000 action camera for his daughter’s no-smartphones-allowed summer camp, which meant that after his daughter returned from said camp, he was free to tinker with this new toy. Although he was not interested in peeling open the camera to ogle its innards, [Richard] was very much into using the WiFi-based remote control without being forced into using the ‘Akaso Go’ smartphone app. To do this, he had to figure out the details of what the Android app does so that it could be replicated. He provided a fake camera WiFi hotspot for the app in order to learn its secrets.
Normally, the camera creates a WiFi hotspot with a specific SSID (iCam-AKASO_C_1e96) and password (1234567890) which the Android app connects to before contacting the camera’s IP address at 192.72.1.1. The app then shows a live view and allows you to copy over snapshots and videos. Initially, [Richard] tried to decompile the Android app using JADX, but the decompiled code contained so many URLs that it was hard to make heads or tails of it. In addition, the app supports many different Akaso camera models, making it harder to focus on the part for this particular camera.
Although we generally assume that opacity is the normal look for animals like us humans, this factoid is only correct for as long as you maintain the dissimilar optical refraction indices of skin and the more aqueous underlying structures. What if you could change the refraction index of skin? If you could prevent the normal scattering at the interface, you could reveal the structures underneath, effectively rendering skin transparent. [Zihao Uo] and others demonstrate this in a paper published in Science.
The substance they used was the common food dye known as tartrazine, which also goes by the names of Yellow 5 and E102 when it is used in food (like Doritos), cosmetics, and drugs. By rubbing the tartrazine into the skin of mice, the researchers were able to observe underlying blood vessels and muscles. Simulations predicted that the dye would change the refraction index mismatch between lipids and water which normally causes the light scattering that creates the skin’s opaque appearance. With the dye rubbed into the skin, the effect worked to a depth of about 3 mm, which makes it useful for some research and possible medical applications, but not quite at the ‘jellyfish-transparency’ levels that some seem to have imagined at the news.
Polypropylene (PP) is a thermoplastic that has a number of properties that sets it apart from other thermoplastics which see common use with 3D printing, including PLA, ABS and nylon (PA). Much like ABS (and the similar ASA), it is a pretty touchy material to print, especially on FDM printers. Over at the [All3DP] site [Nick Loth] provides a quick start guide for those who are interested in using PP with 3D printing, whether FDM, SLS or others.
A nice aspect of printing with PP is that it requires similar temperatures for the extruder (205 – 275 °C) and print bed (80 – 100 °C) as other common FDM filaments. As long as airflow can be controlled in the (enclosed) printer, issues with warping and cracking as the extruded filament cools should not occur. Unlike ABS and ASA which also require an enclosed, temperature-controlled printing space, PP has an advantage that printing with it does not produce carcinogenic fumes (styrene, acrylonitrile, etc.), but it does have the issue of absolutely not wanting to adhere to anything that is not PP. This is where the article provides some tips, such as the use of PP-based adhesive tape on the print bed, or the use of PP-based print plates.
As far as PP longevity and recyclability goes, it compares favorably with ABS and PA, meaning it’s quite resilient and stable, though susceptible to degradation from UV exposure without stabilizers. Recycling PP is fairly easy, though much like with polymers like PLA, the economics and logistics of recycling remain a challenge.
