Rendering of a JetZero blended wing body aircraft with US Air Force markings. (Credit: US Air Force)

Blended Wing Body Passenger Airplanes And The End Of Winged Tubes

November 21, 2024 by Maya Posch 35 Comments

The SR-71 with its blended wing body design. (Photo by Tech. Sgt. Michael Haggerty, US Air Force, 1988)

Ask someone to picture an airplane and they’re likely to think of what is essentially a tube with wings and a stabilizing tail tacked onto one end of said tube. Yet it is also no secret that the lift produced by such a tube is rather poor, even if they’re straightforward for loading cargo (static and self-loading) into them and for deciding where to put in windows. Over the decades a number of alternative airplane designs have been developed, with some of them also ending up being produced. Here most people are probably quite familiar with the US Air Force’s B-2 Spirit bomber and its characteristic flying wing design, while blended wing body (BWB) maintains a somewhat distinctive fuselage, as with for example the B-1 Lancer.

Outside of military airplanes BWBs are a pretty rare sight. Within the world of passenger airplanes the tube-with-wings pattern that the first ever passenger airplanes adopted has persisted with the newest designs, making it often tricky to distinguish one airplane from another. This could soon change, however, with a strong interest within the industry for passenger-oriented BWBs. The reason for this are the significant boosts in efficiency, quieter performance and more internal (useful) volume, which makes airline operators very happy, but which may also benefit passengers.

With that said, how close are we truly to the first BWB passenger airplane delivery to an airline?

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FreeCAD Version 1.0 Released

November 20, 2024 by Maya Posch 23 Comments

After 22 years of development, FreeCAD has at long last reached the milestone of version 1.0. On this momentous occasion, it’s good to remember what a version 1.0 is supposed to mean, as also highlighted in the release blog post: FreeCAD is now considered stable and ready for ‘real work’. One of the most important changes here is that the topological naming problem (TNP) that has plagued FreeCAD since its inception has now finally been addressed using Realthunders’ mitigation algorithm, which puts it closer to parity here with other CAD packages. The other major change is that assemblies are now supported with the assembly workbench, which uses the Ondsel solver.

Other changes include an updated user interface and other features that should make using FreeCAD easier and closer in line with industry standards. In the run-up to the 1.0 release we already addressed the nightmare that is chamfering in FreeCAD, and the many overlapping-yet-uniquely-incomplete workbenches, much of which should be far less of a confabulated nightmare in this bright new 1.0 future.

Naturally, the big zero behind the major version number also means that there will still be plenty of issues to fix and bugs to hunt down, but it’s a promising point of progress in the development of this OSS CAD package.

Most Extreme Hypergravity Facility Starts Up In China With 1,900 Times Earth’s Gravity

November 19, 2024 by Maya Posch 30 Comments

The schematic diagram of the experimental centrifuge. (Credit: Jianyong Liu et al., 2024)

Recently China’s new CHIEF hypergravity facility came online to begin research projects after beginning construction in 2018. Standing for Centrifugal Hypergravity and Interdisciplinary Experiment Facility the name covers basically what it is about: using centrifuges immense acceleration can be generated. With gravity defined as an acceleration on Earth of 1 g, hypergravity is thus a force of gravity >1 g. This is distinct from simple pressure as in e.g. a hydraulic press, as gravitational acceleration directly affects the object and defines characteristics such as its effective mass. This is highly relevant for many disciplines, including space flight, deep ocean exploration, materials science and aeronautics.

While humans can take a g-force (g₀) of about 9 g₀ (88 m/s²) sustained in the case of trained fighter pilots, the acceleration generated by CHIEF’s two centrifuges is significantly above that, able to reach hundreds of g. For details of these centrifuges, this preprint article by [Jianyong Liu] et al. from April 2024 shows the construction of these centrifuges and the engineering that goes into their operation, especially the aerodynamic characteristics. Both air pressure (30 – 101 kPa) and arm velocity (200 – 1000 g) are considered, with the risks being overpressure and resonance, which if not designed for can obliterate such a centrifuge.

The acceleration of CHIEF is said to max out at 1,900 gravity tons (gt, weight of one ton due to gravity), which is significantly more than the 1,200 gt of the US Army Corps of Engineers’ hypergravity facility.

Dial-up Internet Using The Viking DLE-200B Telephone Line Simulator

November 19, 2024 by Maya Posch 24 Comments

Who doesn’t like dial-up internet? Even if those who survived the dial-up years are happy to be on broadband, and those who are still on dial-up wish that they weren’t, there’s definitely a nostalgic factor to the experience. Yet recreating the experience can be a hassle, with signing up for a dial-up ISP or jumping through many (POTS) hoops to get a dial-up server up and running. An easier way is demonstrated by [Minh Danh] with a Viking DLE-200B telephone line simulator in a recent blog post.

This little device does all the work of making two telephones (or modems) think that they’re communicating via a regular old POTS network. After picking up one of these puppies for a mere $5 at a flea market, [Minh Danh] tested it first with two landline phones to confirm that yes, you can call one phone from the other and hold a conversation. The next step was thus to connect two PCs via their modems, with the other side of the line receiving the ‘call’. In this case a Windows XP system was configured to be the dial-up server, passing through its internet connection via the modem.

With this done, a 33.6 kbps dial-up connection was successfully established on the client Windows XP system, with a blistering 3.8 kB/s download speed. The reason for 33.6 kbps is because the DLE-200B does not support 56K, and according to the manual doesn’t even support higher than 28.8 kbps, so even reaching these speeds was lucky.

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Gloriously Impractical: Overclocking The Raspberry Pi 5 To 3.6 GHz

November 18, 2024 by Maya Posch 9 Comments

The Raspberry Pi 5 board strapped to a liquid nitrogen cooler and with ElmorLabs AMPLE-X1 power board attached. (Credit: Pieter-Jan Plaisier, SkatterBencher.com) — The Raspberry Pi 5 board strapped to a liquid nitrogen cooler with an ElmorLabs AMPLE-X1 power board attached. (Credit: Pieter-Jan Plaisier, SkatterBencher.com)

As impractical as most overclocking of computers is these days, there is still a lot of fun to be had along the way. Case in point being [Pieter-Jan Plaisier]’s recent liquid nitrogen-aided overclocking of an unsuspecting Raspberry Pi 5 and its BCM2712 SoC. Previous OCing attempts with air cooling by [Pieter] had left things off at a paltry 3 GHz from the default 2.4 GHz, with the power management IC (PMIC) circuitry on the SBC turning out to be the main limiting factor.

The main change here was thus to go for liquid nitrogen (LN₂) cooling, with a small chipset LN₂ pot to fit on the SBC. Another improvement was the application of a NUMA (non-uniform memory addressing) patch to force the BCM2712’s memory controller to utilize better RAM chip parallelism.

With these changes, the OC could now hit 3.6 GHz, but at 3.7 GHz, the system would always crash. It was time to further investigate the PMIC issues.

The PMIC imposes voltage configuration limitations and turns the system off at high power consumption levels. A solution there was to replace said circuitry with an ElmorLabs AMPLE-X1 power supply and definitively void the SBC’s warranty. This involves removing inductors and removing solder mask to attach the external power wires. Yet even with these changes, the SoC frequency had trouble scaling, which is why an external clock board was used to replace the 54 MHz oscillator on the PCB. Unfortunately, this also failed to improve the final overclock.

We covered the ease of OCing to 3 GHz previously, and no doubt some of us are wondering whether the new SoC stepping may OC better. Regardless, if you want to get a faster small system without jumping through all those hoops, there are definitely better (and cheaper) options. But you do miss out on the fun of refilling the LN₂ pot every couple of minutes.

Thanks to [Stephen Walters] for the tip.

Completing The UE1’s Paper Tape Reader And First Squiggles

November 17, 2024 by Maya Posch 1 Comment

The UE1 tape reader in its nearly finished glory. Note the resistor to regulate the motor speed. (Credit: David Lovett, Usage Electric) — The UE1 tape reader in its nearly finished glory. Note the resistor to regulate the motor speed. (Credit: David Lovett, Usagi Electric)

On today’s installment of UE1 vacuum tube computer construction, we join [David Lovett] once more on the Usagi Electric farm, as he determines just how much work remains before the project can be called done. When we last left off, the paper tape reader had been motorized, with the paper tape being pulled through smoothly in front of the photodiodes. This left [David] with the task to create a PCB to wire up these photodiodes, put an amplification circuit together (with tubes, of course) to amplify the signal from said photodiodes, and add some lighting (two 1-watt incandescents) to shine through the paper tape holes. All of this is now in place, but does it work?

The answer here is a definite kinda, as although there are definitely lovely squiggles on the oscilloscope, bit 0 turns out to be missing in action. This shouldn’t have come as a major surprise, as one of the problems that Bendix engineers dealt with back in the 1950s was effectively the same one: they, too, use the 9th hole on the 8-bit tape as a clock signal, but with this whole being much smaller than the other holes, this means not enough light passes through to activate the photodiode.

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The GREMLIN sensor suite contains several sensing modalities to detect, track, characterize and identify UAP in areas of interest. (Credit: US AARO)

US’s UFO-Hunting Aerial Surveillance System Detailed In Report

November 17, 2024 by Maya Posch 16 Comments

Formerly known as Unidentified Flying Objects, Unidentified Anomalous Phenomena (UAP) is a category of observations that are exactly what the UAP label suggests. This topic concerns the US military very much, as a big part of national security involves knowing everything that appears in the skies. This is the reason for the development of a new sensor suite by the Pentagon called GREMLIN. Recently, a new report has provided more details about what this system actually does.

Managed by the All-domain Anomaly Resolution Office (AARO) within the DoD, GREMLIN blends many different sensors, ranging from radar to ADS-B and RF monitors, together to establish a baseline and capture any anomalies within the 90-day monitoring period to characterize them.

UAPs were a popular topic even before the 1950s when people began to see them everywhere. Usually taking the form of lights or fast-moving objects in the sky, most UAP reports can be readily classified as weather balloons, satellites like Starlink, airplanes, the Northern Lights, the ISS, or planets like Mars and Venus. There are also curious phenomena such as the Hessdalen lights, which appear to be a geological, piezoelectric phenomenon, though our understanding of such natural lighting phenomena remains limited.

But it is never aliens, that’s one thing we know for sure. Not that UFO’s don’t exist. Really.