Wooden Tank’s Movement Hinges On Hinges

When we first looked at this tank, we thought it was pretty cool. The sides are unpainted 1/2″ (12mm) plywood, so it is not flashy. The dimensions came from Google-fu-ing the heck out of the WWII Hetzer and scaling them to 1:6. What knocks our socks off is how much [Bret Tallent] made use of parts you would find in a hardware store or bicycle shop. He uses twin motors from electric bikes, and the wheels look like replacement shopping cart wheels. The best part is the treads, which are dozens of hinges fastened with pairs of bolts and nylon-insert nuts. Something is reassuring about knowing that a repair to your baby is no further than a bike ride.

We don’t know what started [Bret] on his path to sidewalk superiority, but we suspect he is cooped up like the rest of us and looking to express himself. Mini-Hetzer is not licensed by Power Wheels and never will be, so it probably won’t turn into a business anytime soon. There is a complete gallery starting with an empty plywood base, and the pictures tell the story of how this yard Jäger got to this point. There are plans to add a paintball gun and streaming video, so we’d advise that you don’t mess with the jack-o-lanterns on his block this year. Give his gallery a view and see if you don’t become inspired to cobble something clever from the hardware store too. Then, tell us about it.

Another creative hacker used wood for their tank body and the treads as well. If you like your treaded vehicles functional, we have one meant to taxi small planes over the tarmac.

World’s Only Flying Twin Mustang Goes On Sale

Given the incredible success of the P-51 Mustang during the Second World War, it’s perhaps no surprise that the United States entertained the idea of combining two of the iconic fighters on the same wing to create a long-range fighter that could escort bombers into Japan. But the war ended before the F-82 “Twin Mustang” became operational, and the advent of jet fighters ultimately made the idea obsolete. Just five examples of this unique piece of history are known to exist, and the only one in airworthy condition can now be yours.

Assuming you’ve got $12 million laying around, anyway. Even for a flyable WWII fighter, that’s a record setting price tag. But on the other hand, you’d certainly be getting your money’s worth. It took over a decade for legendary restoration expert [Tom Reilly] and his team to piece the plane, which is actually a prototype XP-82 variant, together from junkyard finds. Even then, many of the parts necessary to get this one-of-a-kind aircraft back in the sky simply no longer existed. The team had to turn to modern techniques like CNC machining and additive manufacturing to produce the necessary components, in some cases literally mirroring the design in software so it could be produced in left and right hand versions.

Recovering half of the Twin Mustang in 2008.

We first covered this incredible restoration project back in 2018, before the reborn XP-82 had actually taken its first flight. Since then the plane has gone on to delight crowds with the sound of two counter-rotating Merlin V-12 engines and win several awards at the Oshkosh airshow. The listing for the aircraft indicates it only has 25 hours on the clock, but given its rarity, we can’t blame [Tom] and his crew for keeping the joyrides to a minimum.

As important as it is to make sure these incredible pieces of engineering aren’t lost to history, the recent crash of the B-17G Nine-O-Nine was a heartbreaking reminder that there’s an inherent element of risk to flying these 70+ year old aircraft. A world-class restoration and newly manufactured parts doesn’t remove the possibility of human error or freak weather. While we’d love to see and hear this beauty taxiing around our local airport, it’s a warbird that should probably stay safely in the roost. Hopefully the $12 million price tag will insure whoever takes ownership of the world’s only flying F-82 treats it with the respect it’s due.

The Mark 14 Torpedo — When Just About Everything Goes Wrong, Even The Testing

I am a fan of the saying that those who don’t know history are doomed to repeat it. After all, humans have been building things for a number of centuries and we should learn from the engineers of the past. While you can learn a lot studying successes, sometimes — maybe even most of the time — we learn more from studying failure. The US Navy’s Mark 14 torpedo certainly has a lot to teach us.

The start of the story was the WWI-era Mark 10 torpedo which was fine for its day, but with faster destroyers and some additional data about how to best sink enemy ships it seemed necessary to build a new torpedo that would be faster, carry more explosive charge, and use a new method of detonation. Work started in 1931 with a $143,000 budget which may sound laughable today, but that was a lot of coin in the 1930s. Adjusted for inflation, that’s about $2.5 million.

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Poor Maintenance Could Have Led To Fatal B-17 Crash

In October the Nine-O-Nine, a fully restored Boeing B-17G bomber owned and operated by the Collings Foundation, crashed with thirteen people on board. After landing hard and skidding into the de-icing tanks at the Bradley International Airport, all but the tail and port wing of the 74 year old WWII aircraft was destroyed. Seven lives were lost in the accident, including that of Pilot Ernest “Mac” McCauley, who was regarded as one of the most experienced B-17 pilots in the world.

While the National Transportation Safety Board (NTSB) investigation is still ongoing and hasn’t made a final determination as to what ultimately brought down the Nine-O-Nine, enough serious maintenance issues were uncovered while examining the wreckage that the Federal Aviation Administration (FAA) has decided to rescind the Collings Foundation’s license to conduct any more paid flights on their remaining WWII aircraft. While many have spoken out in support of these “living history” flights, the FAA says they must be conducted in such a way that they don’t hinder the safety of other air traffic.

With the vast majority of the B-17’s airframe gone, the NTSB investigation has focused on the four 1,200 horsepower Wright R-1820 “Cyclone” engines recovered from the crash site. Investigators found that hastily attempted repairs to engine number 4, which is believed to have failed in-flight, were actually hindering normal operation:

Regarding engine 4, to prevent the magneto “P” leads from separating from the
magnetos, someone had attempted to rig the magneto leads in place with safety wire.

Inspection and testing of engine 4 left magneto revealed the movement of the safety-wired lead caused grounding to the case, which rendered the magneto lead inoperative.

Further, all of the spark plugs in the number 3 and 4 engines were found to be fouled and had electrode gaps that were out of tolerance. From an examination of the aircraft’s maintenance records, it was also learned that an arcing and burned wire had been replaced without any investigative steps taken to find what caused the failure to begin with.

With basic maintenance tasks either not being performed or at least done incorrectly, the FAA has called into question the culture of safety at the Collings Foundation. The paper is careful not to directly accuse the Foundation or any of its staff with outright negligence, but the implication seems clear.

The loss of Nine-O-Nine hit especially close to home for Hackaday. Just a month prior to the crash we had the opportunity to tour the aircraft, and came away with a newfound respect for not only those who designed and built the iconic bomber but the brave young men who flew it. Losing such a rare and historically significant aircraft and its crew was already a tragedy, but to find that negligence may be to blame is truly inexcusable.

A Virtual Tour Of The B-17

The Boeing B-17 “Flying Fortress” is arguably the most recognizable aircraft of the Second World War. Made infamous by the daring daylight strategic bombing runs they carried out over Germany, more than 12,000 of these four-engined bombers were produced between 1939 and 1945. Thanks to the plane’s renowned survivability in battle, approximately 60% of them made it through the war and returned home to the United States, only to be rounded up in so-called “boneyards” where they were ultimately cut up and sold as scrap. Today there are fewer than 50 intact Boeing B-17s left in the world, and of those, only 11 remain airworthy.

One of them is Nine-O-Nine, a B-17G built in April 7, 1945. This particular aircraft was built too late to see any combat, although in the 1950s she was fitted with various instruments and exposed to three separate nuclear blasts for research purposes. It’s actually not the real Nine-O-Nine either, the original was scrapped after it completed eighteen bombing runs over Berlin. Without a combat record of its own, this bomber was painted to look like the real Nine-O-Nine in honor of its incredible service record of never losing a crewman.

Since 1986, Nine-O-Nine has been owned by the Collings Foundation, who operate her as a living history exhibit. The bomber flies around the United States with an entourage of similarly iconic WWII aircraft as part of the Wings of Freedom Tour, stopping by various airports and giving the public a chance to climb aboard and see the pinnacle of mid-1940s strategic bombing technology. History buffs with suitably deep pockets can even book a seat on one of the scheduled 30-minute flights that take place at every stop on the Tour.

I was lucky enough to have the The Wings of Freedom Tour pass through my area recently, and couldn’t pass up the opportunity to experience this incredible aircraft first hand. The fact that I’m equal parts a coward and miser kept me from taking a ride aboard the 74 year old Nine-O-Nine, at least for now, but I made sure to take plenty of pictures from inside this lovingly restored B-17G while it was safely on the ground.

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Hacking Shelters And Swimming Pools

How would you survive in a war-torn country, where bombs could potentially fall from the sky with only very short notice? And what if the bomb in question were The Bomb — a nuclear weapon? This concern is thankfully distant for most of us, but it wasn’t always so. Only 75 years ago, bombs were raining down on England, and until much more recently the threat of global thermonuclear war was encouraging school kids to “duck and cover”. How do you protect people in these situations?

The answers, naturally, depend on the conditions at hand. In Britain before the war, money was scarce and many houses didn’t have basements or yards that were large enough to build a family-sized bomb shelter in, and they had to improvise. In Cold War America, building bomb shelters ended up as a boon for the swimming pool construction industry. In both cases, bomb shelters proved to be a test of engineering ingenuity and DIY gumption, attempting to save lives in the face of difficult-to-quantify danger from above.

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Retrotechtacular: Balloons Go To War

To the average person, the application of balloon technology pretty much begins and ends with birthday parties. The Hackaday reader might be able to expand on that a bit, as we’ve covered several projects that have lofted various bits of equipment into the stratosphere courtesy of a high-altitude balloons. But even that is a relatively minor distinction. They might be bigger than their multicolored brethren, but it’s still easy for a modern observer to write them off as trivial.

But during the 1940’s, they were important pieces of wartime technology. While powered aircraft such as fighters and bombers were obviously more vital to the larger war effort, balloons still had numerous defensive and reconnaissance applications. They were useful enough that the United States Navy produced a training film entitled History of Balloons which takes viewers through the early days of manned ballooning. Examples of how the core technology developed and matured over time is intermixed with footage of balloons being used in both the First and Second World Wars, and parallels are drawn to show how those early pioneers influenced contemporary designs.

Even when the film was produced in 1944, balloons were an old technology. The timeline in the video starts all the way back in 1783 with the first piloted hot air balloon created by the Montgolfier brothers in Paris, and then quickly covers iterative advancements to ballooning made into the 1800’s. As was common in training films from this era, the various “reenactments” are cartoons complete with comic narration in the style of W.C. Fields which were designed to be entertaining and memorable to the target audience of young men.

While the style might seem a little strange to modern audiences, there’s plenty of fascinating information packed within the film’s half-hour run time. The rapid advancements to ballooning between 1800 and the First World War are detailed, including the various instruments developed for determining important information such as altitude and rate of climb. The film also explains how some of the core aspects of manned ballooning, like the gradual release of ballast or the fact that a deflated balloon doubles as a rudimentary parachute in an emergency, were discovered quite by accident.

When the film works its way to the contemporary era, we are shown the process of filling Naval balloons with hydrogen and preparing them for flight. The film also talks at length about the so-called “barrage balloons” which were used in both World Wars. Including a rather dastardly advancement which added mines to the balloon’s tethers to destroy aircraft unlucky enough to get in their way.

This period in human history saw incredible technological advancements, and films such as these which were created during and immediately after the Second World War provide an invaluable look at cutting edge technology from a bygone era. One wonders what the alternative might be for future generations looking back on the technology of today.

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