Ambition, Thy Name Is A 3D Printed Transonic R/C Jet

Building anything that flies from scratch is an ambitious undertaking, even if it’s ‘just’ radio-controlled. 3D printing the aircraft isn’t that odd these days, but putting a hot jet engine into a plastic airframe is another ambitous reach. Getting said 3D printed airframe up to the transonic speed of Mach 0.8? Ambition, thy name is Kingchaser. Or at least, that’s the name [The Mach Initiative] give to their very ambitious aircraft, the video about which is embedded below.

The airframe is largely 3D printed from PETG– that’s all the orange bits– but there are carbon fiber rods and an aluminum frame to help take up the strain. The black section around the motor is printed from PPS-CF– that’s Polyphenylene sulfide with carbon fibre–wrapped in carbon fiber to take the heat. This all builds off a smaller PLA version that’s already flown called Kingfisher, which claimed the title of the first 3D printed jet. That flight is on their YouTube channel, if you’re interested.

Now with a bigger aircraft and a much bigger engine– 300 N or 68 lbf of thrust– they’re going for the speed record. If they get even close to the design goal of mach 0.8, they’re absolutely going to leave the world’s fastest drone– a 626 km/h quadcopter we’ve written about— in the dust.

The switch to PETG from PLA, for the record, was to deal with the expected aerodynamic heating at that speed, about 990 km/h or 615 mph. An interesting detail many don’t bother with when it comes to 3D printed airplanes is that the skin has all been polished smooth, since skin drag is dominant at that speed regime. The video is just chock full of those little details that it takes to defeat drag and get to the record speed, and there’s more to come from [The Mach Initiative].

Speaking of remote controlled speed records, we covered another batch of brits take home the land speed record a few years back. May [The Mach Initiative] see such success!

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Examining A World’s Record From The Age Of Steam

There aren’t many speed records that remain unbroken for the greater part of a century, but one of them is that of the fastest steam locomotive. As with so many such things, there’s a bit of controversy and more than one contender, but the one in the record books is the A4 Pacific, Mallard. In 1938, this locomotive thundered down an incline on the London & North Eastern Railway’s mainline in the north of England at 126 MPH. But can that number be taken as reliable? The Institute of Mechanical Engineers has a video in which they investigate.

It’s a fascinating look at the science of railway speed measurement as it existed in 1938, the record itself, and the paper dynamometer roll which recorded it. We’ve placed the video below the break, and in it, we see an in-depth analysis of the noise and inconsistencies in the recording, and see them come to the conclusion that a safer figure to quote would be 124 MPH.

Our assessment is that, of course, the LNER wanted to squeeze every morsel of publicity from it in a game of one-upmanship with their arch-rivals in the London Midland and Scottish railway, so it’s likely that their use of a momentary figure makes sense in that light. Even the best-laid 1930s jointed track would have been bumpy compared to modern continuous rail, and we are guessing that the ancient clerestory dynamometer car would hardly be as smooth-riding as a modern express coach. The achievement of measuring at all with mechanical instruments in such an environment at those speeds would have been tricky, to say the least. It leaves us wondering whether 1930s electronics could have produced some kind of trackside measurement device, but perhaps the LNER trusted their mechanical instruments more. Perhaps the Pennsylvania Railroad should have followed its example.

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Breaking Land Speed Records With An RC Car

Building and running a land speed record car is an expensive business that requires incredibly wealthy benefactors. Doing it on a smaller scale with a radio control car is still pricy, but more within the reach of the individual. [ProjectAir] has been working on just that, and recently set out to break records with a car of his own design.

The car runs a Jetcat 220 engine capable of delivering 220 newtons of thrust, built into a custom aluminium chassis with streamlined bodywork. Early runs saw it reach 112 km/h, but the goal was to push it beyond 150 km/h to break the standing Guinness World Record.

With an RC event running on a local runway, [ProjectAir] had the venue and opportunity to make an attempt. It was tough going, with the car throwing off its nosecose in one run, while rough weather brought further struggles. Strong crosswinds played a role in a violent crash on the car’s fastest pass, which ripped the car apart and destroyed the engine. However, in the end, it had done enough to secure a record at over 152 km/h, even if its later faster efforts didn’t officially count.

It’s clear that the car has come a long way since [ProjectAir’s] initial efforts in 2022, and we can’t wait to see where the project goes next. Video after the break.

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You Might Be Cool, But You’re Not Gas Turbine Motorcycle Cool

For the last four and a half years, [Anders] has been working on a motorcycle project. This isn’t just any old Harley covering a garage floor with oil – this is a gas turbine powered bike built to break the land speed record at Bonneville.

The engine inside [Anders]’s bike is a gas turbine – not a jet engine. There’s really not much difference in the design of these engines, except for the fact that a turbine dumps all the energy into a drive shaft, while a true jet dumps all the energy into the front bumper of the car behind this bike. [Anders] built this engine from scratch, documented entirely on a massive 120 page forum thread. Just about everything is machined by him, bolted to a frame designed and fabricated by him, and with any luck, will break the land speed record of 349 km/h (216mph) on the salt flats of Bonneville.

As with all jet and turbine builds, this one must be heard to be believed. There are a few videos of the turbine in action below, including one where the turbine drives the rear wheel.

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Building A Bike For 100 Miles Per Hour

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As a kid, [Tom] followed all the automotive land speed record attempts on the Bonneville Salt Flats. The cars used in these attempts were all built by guys in their garages, and as a bicycle frame builder, [Tom] is keenly aware of the land speed record for bikes. One thought leads to another, and [Tom] decided he would see how fast one of his frames could go.

Aside from a gigantic gear for his custom bike, [Tom] also needed a little help from a friend. The current land speed record on a bicycle was done by drafting behind a drag racer. [Tom] doesn’t have a drag racer, or a wide expanse of flat open ground in his native England, so he did the next best thing: drafting behind a Ford Zephyr on an abandoned WWII airstrip.

On the runway, [Tom] was able to get his bike up to 80 miles an hour. Wanting to see how fast he could go in ideal conditions, the bike was taken to the garage, put on a pair of rollers, and measured as it was brought up to speed. With a lot of effort, [Tom] was able to get up to 102 miles per hour, incredibly fast for something powered by human muscle.