Retrotechtacular: Railroads In The Jet Age

The front of the Soviet jet train on a monument in Tver, Russia. By Eskimozzz [PD], via Wikimedia Commons.
The front of the Soviet jet train on a monument in Tver, Russia. By Eskimozzz [PD], via Wikimedia Commons.
It started with one of those odd links that pop up from time to time on Hacker News: “The strange and now sadly abandoned Soviet Jet Train from the 1970s“. Pictures of a dilapidated railcar with a pair of jet engines in nacelles above its cab, forlorn in a rusty siding in the Russian winter. Reading a little further on the subject revealed a forgotten facet of the rivalry between Russians and Americans at the height of the Cold War, and became an engrossing trawl through Wikipedia entries, rail enthusiast websites, and YouTube videos.

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A 3D Printed Jet Engine Appears to Function

[amazingdiyprojects] has been working on a 3D printable jet engine. You may remember seeing a 3D printed jet engine grace our front page back in October. That one was beautiful didn’t function. This one flips those values around. [amazingdiyprojects] seems to make a living from selling plans for his projects, so naturally most of the details of the build are hidden from us. But from what we can see in the video clips there are some really interesting solutions here.

Some of the parts appear to be hand-formed sheet metal. Others are vitamins like bearings and an electric starter. We really liked the starter mechanism, pressing in the motor to engage with a spline, or perhaps by friction, to give the starting rotation.

What really caught our attention was casting the hot parts of the printer in refractory cement using a 3D printed mold. It reminds us of the concrete lathes from World War 1. We wonder what other things could be built using this method? Flame nozzles for a foundry? A concrete tea-kettle. It’s pretty cool.

We’re interested to see how the jet engine performs and how others will improve on the concept. Video of it in action after the break.

UPDATE: [amazingdiyprojects] posted a video of the engine being disassembled.

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Casting Turbines For A World Speed Record Motorcycle

[Anders] is going to beat the land speed record for a turbine-powered motorcycle. It’s a project he’s been working on for years now, and just this week, he put the finishing touches on the latest part of the build. He successfully cast the compressor for a gas turbine engine that’s twice as powerful as the one he has now.

This compressor piece was first 3D printed, and this print was used as a positive for a sand – or more specifically petrobond – mold. The material used in the casting is aluminum, fluxed and degassed, and with a relatively simple process, [Anders] came away with a very nice looking cast that only needs a little bit of milling, lathing, and welding to complete the part.

In the interests of accuracy, and just to make sure there’s no confusion, this ‘jet’ engine is actually a gas turbine, of which there are many configurations and uses. The proper nomenclature for this engine is a ‘turboshaft’ because the power is directed to a shaft which drives something else. This is not a new build; we’ve been covering [Anders]’ build for the better part of two years now, and although [Anders] intends to break the world record at the Bonneville salt flats eventually, he won’t be beating the ultimate land speed record – that title goes to a car – and he won’t be beating the speed record for all motorcycles. Instead, [Anders] plans to break the record for experimental propulsion motorcycles, or motorcycles powered by electric motors, steam, jet engines, or in this case, ‘turboshafts’.

It should also be noted that [Anders] frequently does not wear hearing or eye protection when testing his gas turbine engine. That is an exceedingly bad idea, and something that should not be attempted by anyone.

As an additional note for safety, in the video below of [Anders] pouring aluminum into his mold, the ground looks wet. This is terrifically dangerous, and steam explosions can kill and maim even innocent bystanders. This is not something that should be attempted by anyone, but we do thank [Anders] for sharing his project with us.

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Making the Case For Nuclear Aircraft

At any given moment, several of the US Navy’s Nimitz class aircraft carriers are sailing the world’s oceans. Weighing in at 90 thousand tons, these massive vessels need a lot of power to get moving. One would think this power requires a lot of fuel which would limit their range, but this is not the case. Their range is virtually unlimited, and they only need refueling every 25 years. What kind of technology allows for this? The answer is miniaturized nuclear power plants. Nimitz class carriers have two of them, and they are pretty much identical to the much larger power plants that make electricity. If we can make them small enough for ships, can we make them small enough for other things, like airplanes?

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3D Printed Turbofan Features Reverse Thrust

[Harcoreta] has created a 3D printed model of the GE GEnx-1B Turbofan. This is the engine that powers Boeing’s 787 dreamliner. What sets this model apart is that it has a complete working reverse thrust system. A real jet engine would be asking a bit much of 3D printed ABS plastic. This model is more of an Electric Ducted Fan (EDF). An NTM 1400kv 35mm brushless motor hides in the core, cooled by a small impeller.

jet-nakedWhat sets this apart from other jet models is the working reverse thrust system. [Harcoreta] painstakingly modeled the cascade reverse thrust setup on the 787/GEnx-1B combo. He then engineered a way to make it actually work using radio controlled plane components. Two servos drive threaded rods. The rods move the rear engine cowling, exposing the reverse thrust ducts. The servos also drive a complex series of linkages. These linkages actuate cascade vanes which close off the fan exhaust. The air driven by the fan has nowhere to go but out the reverse thrust ducts. [Harcoreta’s] videos do a much better job of explaining how all the parts work together.

The model was printed on an Reprap Prusa I3 at 0.1mm layer height. [Harcoreta] smoothed his prints using acrylic thinner, similar to the acetone vapor method. Unfortunately, [Harcoreta] has only released a few of the design files on rcgroups, but we’re hoping he will drop the whole model. We can’t wait to see a model dreamliner landing just like the big boys!

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Retrotechtacular: The Jet Story

A plane from Britain is met in the US by armed security. The cargo? An experimental engine created by Air Commodore [Frank Whittle], RAF engineer air officer. This engine will be further developed by General Electric under contract to the US government. This is not a Hollywood thriller; it is the story of the jet engine.

The idea of jet power started to get off the ground at the turn of the century. Cornell scholar [Sanford Moss]’ gas turbine thesis led him to work for GE and ultimately for the Army. Soon, aircraft were capable of dropping 2,000 lb. bombs from 15,000 feet to cries of ‘you sank my battleship!’, thus passing [Billy Mitchell]’s famous test.

The World War II-era US Air Force was extremely interested in turbo engines. Beginning in 1941, about 1,000 men were working on a project that only 1/10 were wise to. During this time, American contributions tweaked [Whittle]’s design, improving among other things the impellers and rotor balancing. This was the dawn of radical change in air power.

Six months after the crate arrived and the contracts were signed, GE let ‘er rip in the secret testing chamber. Elsewhere at the Bell Aircraft Corporation, top men had been working concurrently on the Airacomet, which was the first American jet-powered plane ever to take to the skies.

In the name of national defense, GE gave their plans to other manufacturers like Allison to encourage widespread growth. Lockheed’s F-80 Shooting Star, the first operational jet fighter, flew in June 1944 under the power of an Allison J-33 with a remarkable 4,000 pounds of thrust.

GE started a school for future jet engineers and technicians with the primary lesson being the principles of propulsion. The jet engine developed rapidly from this point on.

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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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