Retrotechtacular: The TV Bombs Of WWII

November 14, 2024 by Dan Maloney 39 Comments

Anyone who was around for the various wars and conflicts of the early 2000s probably recalls the video clips showing guided bombs finding their targets. The black-and-white clips came from TV cameras mounted in the nose of the bomb, and were used by bombardiers to visually guide the warhead to the target — often providing for a level of precision amounting to a choice of “this window or that window?” It was scary stuff, especially when you thought about what was on the other side of the window.

Surprisingly, television-guide munitions aren’t exactly new, as this video on TV-guided glide bombs in WWII indicates. According to [WWII US Bombers], research on TV guidance by the US Army Air Force started in 1943, and consisted of a plywood airframe built around a standard 2000-pound class gravity bomb. The airframe had stubby wings for lift and steerable rudders and elevators for pitch and yaw control. Underneath the warhead was a boxy fairing containing a television camera based on an iconoscope or image orthicon, while all the radio gear rode behind the warhead in the empennage. A B-17 bomber could carry two GB-4s on external hardpoints, with a bulky TV receiver provided for the bombardier to watch the bomb’s terminal glide and make fine adjustments with a joystick.

In testing, the GB-4 performed remarkably well. In an era when a good bombardier was expected to drop a bomb in a circle with a radius of about 1,200′ (365 meters) from the aim point, GB-4 operators were hitting within 200′ (60 meters). With results like that, the USAAF had high hopes for the GB-4, and ordered it into production. Sadly, though, the testing results were not replicated in combat. The USAAF’s 388th Bomber Group dropped a total of six GB-4s against four targets in the European Theater in 1944 with terrible results. The main problem reported was not being able to see the target due to reception problems, leaving the bombardiers to fly blind. In other cases, the bomb’s camera returned a picture but the contrast in the picture was so poor that steering the weapon to the target was impossible. On one unfortunate attack on a steel factory in Duren, Germany, the only building with enough contrast to serve as an aiming point was a church six miles from the target.

The GB-4’s battlefield service was short and inglorious, with most of the 1,200 packages delivered never being used. TV-guided bombs would have to wait for another war, and ironically it would be the postwar boom in consumer electronics and the explosion of TV into popular culture would move the technology along enough to make it possible.

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Retrotechtacular: Color TV

November 12, 2024 by Al Williams 20 Comments

We have often wondered if people dreamed in black and white before the advent of photography. While color pictures eventually became the norm, black and white TV was common for many years. After all, a TV set was a big investment, so people didn’t run out and buy the latest TV every year. Even if you did buy a new or used TV, a black and white model was much less expensive and, for many years, some shows were in black and white anyway. RCA, of course, wanted you to buy a color set. [PeriscopeFilm] has a 1963 promotional film from RCA extolling the virtues of a color set. The video also shows something about how the sets were made, as you can see below.

We aren’t sure we’d have led with the idea that color could save your life in this context, but we have to salute the melodrama. There is a good bit of footage of picture tube manufacturing, although the technical detail is — understandably — aimed at the general public.

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Retrotechtacular: Making Enough Merlins To Win A War

October 25, 2024 by Dan Maloney 16 Comments

From the earliest days of warfare, it’s never been enough to be able to build a deadlier weapon than your enemy can. Making a sharper spear, an arrow that flies farther and straighter, or a more accurate rifle are all important, but if you can’t make a lot of those spears, arrows, or guns, their quality doesn’t matter. As the saying goes, quantity has a quality of its own.

That was the problem faced by Britain in the run-up to World War II. In the 1930s, Rolls-Royce had developed one of the finest pieces of engineering ever conceived: the Merlin engine. Planners knew they had something special in the supercharged V-12 engine, which would go on to power fighters such as the Supermarine Spitfire, and bombers like the Avro Lancaster and Hawker Hurricane. But, the engine would be needed in such numbers that an entire system would need to be built to produce enough of them to make a difference.

“Contribution to Victory,” a film that appears to date from the early 1950s, documents the expansive efforts of the Rolls-Royce corporation to ramp up Merlin engine production for World War II. Compiled from footage shot during the mid to late 1930s, the film details not just the exquisite mechanical engineering of the Merlin but how a web of enterprises was brought together under one vast, vertically integrated umbrella. Designing the engine and the infrastructure to produce it in massive numbers took place in parallel, which must have represented a huge gamble for Rolls-Royce and the Air Ministry. To manage that risk, Rolls-Royce designers made wooden scale models on the Merlin, to test fitment and look for potential interference problems before any castings were made or metal was cut. They also set up an experimental shop dedicated to looking at the processes of making each part, and how human factors could be streamlined to make it easier to manufacture the engines.

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Retrotechtacular: Another Thing Your TV No Longer Needs

October 2, 2024 by Jenny List 23 Comments

As Hackaday writers we don’t always know what our colleagues are working on until publication time, so we all look forward to seeing what other writers come up with. This week it was [Al Williams] with “Things Your TV No Longer Needs“, a range of gadgets from the analogue TV era, now consigned to the history books. On the bench here is a device that might have joined them, so in taking a look at it now it’s by way of an addendum to Al’s piece.

When VHF Was Not Enough

In a Dutch second-had store while on my hacker camp travels this summer, I noticed a small grey box. It was mine for the princely sum of five euros, because while I’d never seen one before I was able to guess exactly what it was. The “Super 2” weighing down my backpack was a UHF converter, a set-top box from before set-top boxes, and dating from the moment around five or six decades ago when that country expanded its TV broadcast network to include the UHF bands. If your TV was VHF it couldn’t receive the new channels, and this box was the answer to connecting your UHF antenna to that old TV.

It’s a relatively small plastic case about the size of a chunky paperback book, on the front of which is a tuning knob and scale in channels and MHz, on the top of which are a couple of buttons for VHF and UHF, and on the back are a set of balanced connectors for antennas and TV set. It’s mains powered, so there’s a mains lead with an older version of the ubiquitous European mains plug. Surprisingly it comes open with a couple of large coin screws on the underside, so it’s time to take a look inside. Continue reading “Retrotechtacular: Another Thing Your TV No Longer Needs” →

Retrotechtacular: Powerline Sagging And Stringing In The 1950s

August 17, 2024 by Dan Maloney 13 Comments

While high-voltage transmission lines are probably the most visible components of the electrical grid, they’re certainly among the least appreciated. They go largely unnoticed by the general public — quick, name the power line closest to you right now — at least until a new one is proposed, causing the NIMBYs and BANANAs to come out in force. To add insult to injury, those who do notice the megastructures that make modern life possible rarely take a moment to appreciate the engineering that goes into stringing up hundreds of miles of cable and making sure it stays up.

Not so the Bonneville Power Administration, the New Deal-era federal agency formed to exploit the hydroelectric abundance of the Pacific Northwest of the United States, which produced this 1950 gem detailing the stringing and sagging of power lines. Unsurprisingly, the many projects needed to wire together the often remote dams to the widely distributed population centers in an area that was only just starting to see growth began in the BPA’s offices, where teams of engineers hunched over desks worked out the best routes. Paper, pencil, and slide rules were the tools of the trade, along with an interesting gadget called a conductor sag template, a hardware implementation of the catenary equation that allowed the “sagger” to determine the height of each tower. The conductors, either steel-cored aluminum or pure copper, were also meticulously selected based on tensile strength, expected wind and ice loading, and the electrical load the line was expected to carry.

Once the engineers had their say, the hard work of physically stringing the wires began out in the field. One suspects that the work today is much the same as it was almost eighty years ago, save for much more stringent health and safety regulations. The prowess needed to transfer the wires from lifting sheaves to the insulators is something to behold, and the courage required to work from ladders hanging from wires at certain death heights is something to behold. But to our mind, the real heroes were the logistics fellows, who determined how much wire was needed for each span and exactly where to stage the reels. It’s worth sparing a moment’s thought for the daring photographer who captured all this action, likely with little more than a leather belt and hemp rope for safety.

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Retrotechtacular: Ford Model T Wheels, Start To Finish

July 18, 2024 by Dan Maloney 20 Comments

There’s no doubt that you’ll instantly recognize clips from the video below, as they’ve been used over and over for more than 100 years to illustrate the development of the assembly line. But those brief clips never told the whole story about just how much effort Ford was forced to put into manufacturing just one component of their iconic Model T: the wheels.

An in-house production of Ford Motors, this film isn’t dated, at least not obviously. And with the production of Model T cars using wooden spoked artillery-style wheels stretching from 1908 to 1925, it’s not easy to guess when the film was made. But judging by the clothing styles of the many hundreds of men and boys working in the River Rouge wheel shop, we’d venture a guess at 1920 or so.

Production of the wooden wheels began with turning club-shaped spokes from wooden blanks — ash, at a guess — and drying them in a kiln for more than three weeks. While they’re cooking, a different line steam-bends hickory into two semicircular felloes that will form the wheel’s rim. The number of different steps needed to shape the fourteen pieces of wood needed for each wheel is astonishing. Aside from the initial shaping, the spokes need to be mitered on the hub end to fit snugly together and have a tenon machined on the rim end. The felloes undergo multiple steps of drilling, trimming, and chamfering before they’re ready to receive the spokes.

The first steel component is a tire, which rolls down out of a furnace that heats and expands it before the wooden wheel is pressed into it. More holes are drilled and more steel is added; plates to reinforce the hub, nuts and bolts to hold everything together, and brake drums for the rear wheels. The hubs also had bearing races built right into them, which were filled with steel balls right on the line. How these unsealed bearings were protected during later sanding and grinding operations, not to mention the final painting step, which required a bath in asphalt paint and spinning the wheel to fling off the excess, is a mystery.

Welded steel spoked wheels replaced their wooden counterparts in the last two model years for the T, even though other car manufacturers had already started using more easily mass-produced stamped steel disc wheels in the mid-1920s. Given the massive infrastructure that the world’s largest car manufacturer at the time devoted to spoked wheel production, it’s easy to see why. But Ford eventually saw the light and moved away from spoked wheels for most cars. We can’t help but wonder what became of the army of workers, but it probably wasn’t good. So turn the wheels of progress.

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Retrotechtacular: The Tools And Dies That Made Mass Production Possible

July 3, 2024 by Jenny List 15 Comments

Here at Hackaday we’re suckers for vintage promotional movies, and we’ve brought you quite a few over the years. Their boundless optimism and confidence in whatever product they are advancing is infectious, even though from time to time with hindsight we know that to have been misplaced.

For once though the subject of today’s film isn’t something problematic, instead it’s a thing we still rely on today. Precision manufacturing of almost anything still relies on precision tooling, and the National Tool and Die Manufacturers Association is on hand in the video from 1953 below the break to remind us of the importance of their work.

The products on show all belie the era in which the film was made: a metal desk fan, CRT parts for TVs, car body parts, a flight of what we tentatively identify as Lockheed P-80 Shooting Stars, and a Patton tank. Perhaps for the Hackaday reader the interest increases though when we see the training of an apprentice toolmaker, a young man who is being trained to the highest standards in the use of machine tools. It’s a complaint we’ve heard from some of our industry contacts that it’s rare now to find skills at this level, but we’d be interested to hear views in the comments on the veracity of that claim, or whether in a world of CAD and CNC such a level of skill is still necessary. Either way we’re sure that the insistence on metrology would be just as familiar in a modern machine shop.

A quick web search finds that the National Tool and Die Manufacturers Association no longer exists, instead the search engine recommends the National Tooling And Machining Association. We’re not sure whether this is a successor organisation or a different one, but it definitely represents the same constituency. When the film was made, America was at the peak of its post-war boom, and the apprentice would no doubt have gone on to a successful and pretty lucrative career. We hope his present-day equivalent is as valued.

If you’re of a mind for more industrial process, can we direct you at die casting?

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