Why The Saturn V Used Kerosene For Its Hydraulics Fluid

November 11, 2024 by 38 Comments

We usually think of a hydraulic system as fully self-contained, with a hydraulic pump, tubing, and actuators filled with a working fluid. This of course adds a lot of weight and complexity that can be undesirable in certain projects, with the Saturn V Moon rocket demonstrating a solution to this which is still being used to this day. In a blast-from-the-past, a December 1963 article originally published in Hydraulics & Pneumatics details the kerosene-based hydraulics (fueldraulics) system for the S-1C stage’s gimbal system that controlled the four outer engines.

Rather than a high-pressure, MIL-H-5606 hydraulic oil-based closed loop as in the Saturn I, this takes kerosene from the high-pressure side of the F1 rocket engine’s turbopump and uses it in a single-pass system. This cuts out a separate hydraulic pump, a hydraulic reservoir, which was mostly beneficial in terms of reducing points of failure (and leaks), ergo increasing reliability. Such was the theory at the time at least, and due to issues with RP-1 kerosene’s relatively low flash point and differences in lubricity properties, ultimately RJ-1, RP-1 and MIL-H-5606 were used during checkout leading up to the launch.

In hindsight we know that this fueldraulic system worked as intended with all Saturn V launches, and today it’s still used across a range of aircraft in mostly jet engines and actuators elsewhere of the Boeing 777 as well as the F-35. In the case of the latter it only made the news when there was an issue that grounded these jets due to badly crimped lines. Since fueldraulics tends to be lower pressure, this might be considered a benefit in such cases too, as anyone who has ever experienced a hydraulic line failure can attest to.

Featured image: Gimbal systems proposed for the F-1, oxygen-kerosene engine with a fueldraulic system. (Source: Hydraulics & Pneumatics, 1963)

Cheap Sensor Changes Personality

November 10, 2024 by 24 Comments

If you want to add humidity and temperature sensors to your home automation sensor, you can — like [Maker’s Fun Duck] did — buy some generic ones for about a buck. For a dollar, you get a little square LCD with sensors and a button. You even get the battery. Can you reprogram the firmware to bend it to your will? As [Duck] shows in the video below, you can.

The device advertises some custom BLE services, but [Duck] didn’t want to use the vendor’s phone app, so he cracked the case open. Inside was a microcontroller with Bluetooth, an LCD driver, a sensor IC, and very little else.

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Welcome To SubTropolis: The Limestone Mine Turned Climate-Controlled Business Complex

November 10, 2024 by 32 Comments

After extracting all the useful stuff from a mine, you are often left with a lot of empty subterranean space without a clear purpose. This was the case with the Bethany Falls limestone mine, near Kansas City, Missouri, which left a sprawling series of caverns supported by 16′ (4.9 meter) diameter pillars courtesy of the used mining method. As detailed by [Benjamin Hunting] in a recent article on the Hagerty site, this made it a fascinating place for a  business complex development now called SubTropolis that among other things is used for car storage by Ford and long-term stamp storage by the US Post Office. (Check out their cool period photos!)

The reason for this is the extremely stable climate within these man-made caverns, with relative humidity hovering around a comfortable 40% and temperatures stable year-round at about 21 °C (70 °F), making it ideal for storing anything that doesn’t like being placed outdoors, while saving a lot on airconditioning costs. With Ford one of the biggest companies in SubTropolis, this means that many companies providing customization services for vehicles have also moved operations inside the complex.

With the only negative being a lack of daylight, it seems like the perfect place for many businesses and (evil) lairs, assuming electrical power and constant air circulation are provided.

Featured image: “Subtropolis” by [ErgoSum88]

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Hackaday Links: November 10, 2024

November 10, 2024 by 21 Comments

Fair warning, while the first item this week has no obvious connection to hacking, when 43 Rhesus monkeys escape from a lab, it’s just something that needs to be discussed. The tiny primates broke free from Alpha Genesis, a primate research facility in South Carolina. The monkey jailbreak seems to have occurred sometime on Wednesday, shortly after which the sheriff of Beaufort County was notified to be on the lookout for the tribe. Luckily, none of the animals has been used in any kind of infectious disease research, so this likely won’t be the origin story for anything apocalyptic. At least some of the animals were quickly located, doing their monkey thing in the woods and getting to swing from real trees for probably the first time in their lives. Alpha Genesis employees are trying to lure the monkeys back to captivity with food, but we suspect they’re too smart for that. They’ll probably come back on their own recognizance or when they get bored and realize that the real world isn’t all they thought it would be. When it’s all done we’d love to hear details about the breakout; was it something the monkeys got together and planned, or did one of the humans mess up?

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Building A Motor Feed For The UE1 Vacuum Tube Computer’s Paper Tape Reader

November 10, 2024 by 9 Comments

Building a paper tape reader by itself isn’t super complicated: you need a source of light, some photoreceptors behind the tape to register the presence of holes and some way to pull the tape through the reader at a reasonable rate. This latter part can get somewhat tricky, as Usagi Electric‘s [David Lovett] discovered while adding this feature to his vacuum tube-era DIY reader. This follows on what now seems like a fairly simple aspect of the photosensors and building a way to position said photosensors near the paper tape.

As the feed rate of the paper tape is tied to the reading speed, and in the case of [David]’s also contains the clock for the custom tube-based UE1 computer, it determines many of the requirements. With 8 bits per line, the tape forms the ROM for the system, all of which has to be executed and used immediately when read, as there is no RAM to load instructions into. This also necessitates the need to run the tape as an endless loop, to enable ‘jumping’ between parts of this paper-based ROM by simple masking off parts of the code until the desired address is reached.

For the motor a slot car motor plus speed-reduction gear was chosen, with a design to hold these then designed in FreeCAD. Courtesy of his brother’s hobby machine shop and a CAD professional’s help, producing these parts was very easy, followed by final assembly. Guides were added for the tape, not unlike with a cassette player, which allowed the tape to be pulled through smoothly. Next up is wiring up the photodiodes, after which theoretically the UE1 can roar into action directly running programs off paper tape.

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Component Tester Teardown

November 10, 2024 by 9 Comments

In the modern age, when you hear “component tester” you probably think of one of those cheap microcontroller-based devices that can identify components and provide basic measurements on an LCD screen. However, in the past, these were usually simple circuits that generated an XY scope plot. The trace would allow an experienced operator to identify components and read a few key parameters. [Thomas] tears down an old Hameg device that uses this principle in the video below.

The unit is in a nice enclosure and has a feature that controls the amount of current the unit uses in the excitation signal. It plugs into the wall, and you can connect the component under test with either test leads or a socket. The output, of course, is a pair of BNCs for the scope’s X and Y inputs.

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Building A DIY Nipkow Disk Display

November 10, 2024 by 27 Comments

Before flat screen technologies took over, we associate TV with the CRT. But there were other display technologies that worked, they just weren’t as practical. One scheme was the Nipkow disk, and [Bitluni] decided to build a working demonstration of how such a system works.

Essentially, there’s a spinning disk with a spiral pattern of holes in it. As the disk spins, a light behind it turns on or off. If you time everything right, you get an image that can move. This particular model uses stepper motors, which is a bit of a modern concession.

The result was actually much better than you might guess, but a far cry from a modern display device, of course. The screen material needed a little tweaking, but even the initial results were very impressive. If this were trying to be practical, it would probably require a bit more work on the light source and screen.

Interestingly, the Nipkow disk arrangement was just as suitable for scanning as displaying. Instead of a light behind the wheel, you simply used a light sensor. Of course, in practice, getting everything synchronized and mass-producing high-resolution sets would have been a tremendous challenge a century ago.

Not that people didn’t try. There were even color systems using mechanical wheels. In the 1930s, people were sure your TV would contain spinning disks.

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