Micro Tesla Turbine is an Engineering Tour de Force

A corollary to Godwin’s Law ought to be that any Hackaday post that mentions Nikola Tesla will have a long and colorful comment thread. We hope this one does too, but with any luck it’ll concentrate on the engineering behind this tiny custom-built Telsa turbine.

For those not familiar with Mr. Tesla’s favorite invention, the turbine is a super-efficient design that has no blades, relying instead on smooth, closely spaced discs that get dragged along by the friction of a moving fluid. [johnnyq90]’s micro version of the turbine is a very accomplished feat of machining. Although at first the build appears a bit janky, as it progresses we see some real craftsmanship – if you ever doubt that soda can aluminum can be turned, watch the video below. The precision 25mm rotor goes into a CNC machined aluminum housing; the way the turned cover snaps onto the housing is oddly satisfying. It looks like the only off-the-shelf parts are the rotor bearings; everything else is scratch-made. The second video ends with a test spool-up that sounds pretty good. We can’t wait for part 3 to find out how fast this turbine can turn.

Size matters, and in this case, small is pretty darn impressive. For a larger treatment of a Tesla turbine, see this one made of old hard drive platters.

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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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Retrotechtacular: The J-57 Afterburner Engine

The J-57 afterburner engine appeared in many airplanes of notable make, including the F-101, -102, and -103. This USAF training film shows the parts of the J-57, explains the complex process by which the engine produces thrust, and describes some maintenance and troubleshooting procedures.

The name of this game is high performance. Precision thrust requires careful rigging of the engine’s fuel control linkage through a process called trimming. Here, the engine fuel control is adjusted with regard to several different RPM readings as prescribed in the manual.

One of the worst things that can happen to a J-57 is known as overtemping. This refers to high EGT, or exhaust gas temperature. If EGT is too high, the air-fuel ratio is not ideal. Troubleshooting a case of high EGT should begin with a check of the lines and the anti-icing valve. If the lines are good and the valve is closed, the instruments should be checked for accuracy. If they’re okay, then it’s time for a pre-trimming inspection.

In addition to EGT, engine performance is judged by RPM and PP7, the turbine discharge pressure. If RPM and PP7 are within spec and the EGT is still high, the engine must be pulled. It should be inspected for leaks and hot spots, and the seals should be examined thoroughly for cracks and burns. The cause for high EGT may be just one thing, or it could be several small problems. This film encourages the user to RTFM, which we think is great advice in general.

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Riding rockets and jets around the frozen wastes of Sweden

An attentive reader tipped us off to the guys at Mobacken Racing (translation), a group of Swedes dedicated to the art and craft of putting jet and rocket engines on go karts and snowmobiles.

One of the simpler builds is a pulse jet sled. Pulse jets are extremely simple devices – just a few stainless steel tubes welded together and started with a leaf blower. The simplicity of a pulse jet lends itself to running very hot and very loudly; the perfect engine for putting the fear of a Norse god into the hearts of racing opponents.

Pulse jets are a bit too simple for [Johansson], so he dedicates his time towards building a jet turbine engine. Right now it’s only on a test stand, but there’s still an awesome amount of thrust coming out of that thing, as shown in the video after the break.

In our humble opinion, the most interesting build is the 1000 Newton liquid fuel rocket engine. The liquid-cooled engine guzzles NOX and methanol, and bears a striking resemblance to liquid fuel engines we’ve seen before. Sadly, there are no videos of this engine being fired (only pics of it strapped to a go-kart), but sit back and watch a couple other hilariously overpowered engines disturbing a tranquil sylvan winter after the break.

Edit: [Linus Nilsson] wrote in to tell us while the guys at Mobacken Racing are good friends, [Linus], his brother, and third guy (his words) are responsible for the pulse jet sled. The pulse jet is actually ‘valved’ and not as simple as a few stainless steel tubes. The pulse jet isn’t started by a leaf blower, either, but a four kilowatt fan. [Linus]’ crew call themselves Svarthalet racing, and you can check out the Google translation here.

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Low-voltage wind turbine lighting


Instructables user [Dustyn] recently constructed a wind-based lantern to provide a bit of free, renewable light in urban settings. The project is based around a vertical-axis wind turbine, which she says are better suited to these environments since wind often comes from all different directions. Despite their lower efficiency compared their horizontal-axis brethren, this style of turbine seems to fit her needs quite well.

She provided a complete bill of materials, down to the last screw and washer you would need to replicate her work. The wind sails were constructed from thin aluminum flashing, and inserted between two acrylic sheets. These were then mounted to the central aluminum shaft of the turbine, which drives the stepper motor built into the base.

The current from the stepper motor is rectified and run through a pair of capacitors before being used to light the attached LED. This allows the bipolar motor to provide current regardless of the direction the turbine is turning, and the caps smooth things out so that the LEDs don’t flicker wildly under varying wind conditions. The turbine is not going to light up a full city block, but it is definitely a nice alternative to sun jars.

Stick around to see a video of the turbine mechanism in action.

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Build your own vertical axis wind turbine

You can build a copy of this vertical wind turbine in a weekend and it won’t cost you all that much. Applied Sciences developed the hardware and they’re sharing all for the build details. You will be taken through every part of the build starting with the fin assembly which is made from stove-pipe material. This is a perfect raw material because it is already curved and suited for aerodynamic use in much the same way that PVC pipe is for making fins and we would expect it to be a bit lighter in weight. You will also need to turn your own coils when assembling the stator. This particular build process uses nine coils embedded in fiberglass. They remain stationary while two different discs, each containing a dozen rare earth magnets, rotate in close proximity to induce a current. It outputs three-phase AC current which can be turned to DC using a bridge rectifier and then further regulated for storage in batteries.

[Thanks Miguel]

Gas turbine jetpack – test pilots wanted

Feeling brave and ready to strap on this jet pack? Well, that’s not all of it. What you see above is just the manifold with two nozzles that can be aimed for control. The gas turbine engine that is being designed for the project will attach to the large circular coupling on top. The finished suit, called a Monocopter, should weigh in at about 265 pounds. That kind of weight makes us think they should include a robotic exoskeleton to help support it during takeoff, landing, and just when standing around. This thing already looks like it belongs to a villain from the Megaman series. Here’s hoping it’s used for good and not to help produce an army of mean robots.

[Thanks Rob]