A Peek Inside A 747 Fuel Gauge

June 11, 2023 by Matthew Carlson 28 Comments

It isn’t that often that we civilians get the chance to closely examine the fantastic internals that make up the modern marvels of avionic engineering. Luckily for us, [Glen] got his hands on a 747 fuel gauge and tore it down for our benefit. Not only does he tear it down, but he also builds a controller to display values.

Unlike your typical automotive fuel gauge that reports the distance from the top of the tank to the fuel level, this gauge reports the number of pounds of fuel. The fact that the indicator pictured above can go all the way to 95,000 pounds of fuel hits home the sheer scale of the fuel tanks on a 747 compared to your Volvo. Of course, where this gets interesting is the teardown with the metal sleeve removed. A 400 HZ AC servo motor moves the pointer and counter through the gearing with the help of a feedback potentiometer. The resistance tolerance is only 3%, as there are adjustment knobs on the back. But the linearity spec is only 0.06%, putting this part in a different grade from most pots.

One of the indicators was in worse shape than the others, so [Glen] got to work tapping into the internals of the gauge to drive the motor directly. A custom AC power supply repurposed from another project provided power, and a Raspberry Pi Pico was the PID controller. For [Glen], it isn’t all roses. Unfortunately, a noisy spot around 22,500 prevents accurate placement around there.

The code is up on GitHub, and we love having a gauge on the desk to show whatever value we like. If you are curious about more 747 instruments, this retro control unit might interest you.

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Floppy Disks Still Used To Update 747 Flight Software

August 12, 2020 by Lewin Day 96 Comments

For garden variety daily computing tasks, the floppy disk has thankfully been a thing of the past for quite some time. Slow, limited in storage and easily corrupted, few yearn for the format to return, even if there is some lingering nostalgia for the disks. As it turns out, though, there is still hardware that relies on floppies – namely, the Boeing 747-400, as The Register reports.

The news comes from the work of Pen Test Partners, who recently inspected a 747 being retired as a result of the coronavirus pandemic. The floppy disks are used to load navigational databases which need to be updated regularly, every 28 days. Engineers responsible for loading updates must perform the process manually on the ground.

Efforts have been made in some areas to replace the disks with more modern technology. As Aviation Today covered in 2014, legacy aircraft often require updates involving up to eight floppy disks, leading to slow updates that can cause flight delays. As anyone familiar with the reliability of floppy media knows, it only takes one bad disk to ruin everything. While retrofits are possible, it’s more likely that airlines will simply stick with the technology until the legacy airplanes are retired. Certifying new hardware for flight is a major cost that is difficult to justify when the current system still works.

Floppies continue to cling to relevance, even if for most of us it’s simply as the save icon. We’ve also seen floppies used as an even more inefficient method of data entry. It turns out you can even fit an entire podcast on one, too!

Hackaday Links: September 2, 2018

September 2, 2018 by Brian Benchoff 17 Comments

It’s (was, is?) the end of August, and that means the entire dreadlocked population of San Francisco is out in the middle of the Nevada Desert for a week. Yes, it’s Burning Man, and as always we have a host of builds that make you ask, ‘how did they do that, and how did they get that here’.

For the last few years, the greatest logistical feat of art cars is the 747. Yes, it’s the fuselage of a 747, turned into an art car. The top deck is a convertible. The biggest question surrounding this 747 is how do you transport this thing? You can’t fly it in (well, you could, once), it’s not going to fit on a train, and it’s extraordinarily long. Now we have an answer: they did it on a truck. The 747 was stationed in the Mojave, and from there it’s a relatively quick shot up Nevada to Black Rock City. Several power lines had to be raised, and you’re still looking at an enormous logistical endeavour.

I’m saying it now. Sphere, the 1998 movie with Dustin Hoffman. There’s a 25 meter diameter mirror ball that looks like the sphere in Sphere. It’s inflatable, so that takes care of the obvious questions, but we’re still asking how this thing looks in person, how massive wind storms are going to affect what is basically a gigantic ~~sale~~ sail, and what the reflections of the sun will actually do. I suppose being convex, you’re not going to get the accidental architectural parabolic mirror effect that melts cars, but one can always hope.

Want a neat story on the features of Burning Man that doesn’t get a lot of press? IEEE Spectrum did a feature on Black Rock City airport. For one week a year, it is the third busiest airport in Nevada, behind McCarren and Reno. It’s also a towered, yet uncontrolled airport. This makes no logical sense, but it’s something that can happen with FAA regs.

[alicestewwwart] has left us with a quandary. She’s creating highly artistic circuits out of ICs, discrete parts, and wire. These circuits are functional, but we don’t know what to call them. They’re not quite deadbug, because SMD parts don’t have legs, and ‘deadbug’ gets its name from upside down DIPs that looks like dead centipedes. It’s not Manhattan style, although this might be closer to Manhattan than deadbug. So what is it? Leave your answer in the comments.

The Largest Aircraft Ever Built Will Soon Launch Rockets To Space

August 29, 2018 by Brian Benchoff 57 Comments

Deep in the mojave, the largest aircraft ever made will soon be making test flights. This is the Stratolaunch, and it’s measured the largest to ever fly based on wingspan. The Stratolaunch was constructed out of two 747s, and is designed for a single purpose: as a mobile launch platform for orbital rockets.

There are a couple of ways to measure the size of an aircraft. The AN-225 Mriya has the highest payload capacity, but only one of those was ever built (though that might change soon). The Spruce Goose was formerly the largest aircraft by wingspan, but it only flew once, and only in ground effect. The Stratolaunch is in another category entirely. This is an aircraft that contains some of the largest composite structures on the planet. Not only can you park a school bus between the fuselages of the Stratolaunch, you can strap that school bus to the plane and carry it up to 30,000 feet.

But why build this astonishing aircraft? The reasons go back more than a decade, and the end result is a spaceplane.

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Hackaday Links: September 10, 2017

September 10, 2017 by Brian Benchoff 4 Comments

Hackaday is 13! We’re going through a bit of a rebellious phase. There’s hair where there wasn’t hair before. Thirteen years ago (Sept. 5, 2004), [Phil Torrone] published the first Hackaday Post. [Phil] posted a great writeup of the history of Hackaday over on the Adafruit blog — we were saved from the AOL borg because of the word ‘hack’ — and interviewed the former and current editors of your favorite DIY website. Here’s to 13 more years and to [Phil] finding a copy of the first version of the Jolly Wrencher designed in Macromedia Flash.

Hackaday is having an unconference in the UK! Tickets for next weekend’s event went fast, but don’t worry — we’re hosting a Bring A Hack the day before.

Hurricanes are an awesome force of nature. As we learned from Harvey a week ago, livestreamed footage from the eyewall of a hurricane is fascinating. [Jeff Piotrowski] seems to be the streamer of choice. If you’re looking for something to gawk at, here you go.

Another burn is over, and I still have no idea how they moved the fuselage of a 747 from Palmdale to the playa.

You know we’re doing this whole Hackaday Prize thing where we’re giving a ton of money to people for creating cool hardware, right? We’re almost done with that. The last round of The Hackaday Prize is going on right now. The theme is anything goes, or rather there is no theme. The goal of this round is to build cool stuff. This round ends on October 16th, and yes, we’ll have the results for the Assistive Technologies round out shortly.

[Prusa] makes a lot of printers, and that means he needs to make a lot of parts to make a lot of printers. Obviously, a PTFE-cutting robot is the solution to this problem

October 5th is the Open Source Hardware Summit in Denver. Hackaday and Tindie are going, and it’s going to be a blast. The location has moved in the last week — now it’s about half a mile away from the old venue. The speaker schedule is up, board nominations are open, and somewhere, someone is organizing a Lulzbot/Sparkfun booze cruise the day after the summit. I should be getting a van to add capacity to this trip, so if you’re interested leave a note in the comments.

Restoring A Retro 747 Control Display Unit

June 20, 2017 by John Baichtal 17 Comments

Anyone who’s into retro aviation gear falls in love with those mysterious displays, dials, keypads, banks of knife switches. There’s a lot of sexy in those devices, built with high standards in a time when a lot of it was assembled by hand.

[Jeremy Gilbert] bought a 747-200’s Control Display Unit (CDU)– the interface with the late ’70s in-flight computer–and is bringing it back to life in a Hackaday.io project. His goal is to get it to light up and operate just as if it were installed in a 747.

Of particular interest is the display, which turned out to consist of a series of 5×7 matrices (seen on the right) controlled by chips no one uses any more. However, [Jeremy] found a blog post where someone had hacked out Arduino code for a cousin of the chip, saving him a lot of time. However, he’s got a lot more sleuthing yet to do.

If you’re into retro displays, we’ve mentioned a number of good ones, including the legendary Apollo DSKY and an awesome retrocomputer.