That NASA EM Drive Paper: An Expert Opinion

A week or two ago we featured a research paper from NASA scientists that reported a tiny but measurable thrust from an electromagnetic drive mounted on a torsion balance in a vacuum chamber. This was interesting news because electromagnetic drives do not eject mass in the way that a traditional rocket engine does, so any thrust they may produce would violate Newton’s Third Law. Either the Laws Of Physics are not as inviolate as we have been led to believe, or some other factor has evaded the attempts of the team to exclude or explain everything that might otherwise produce a force.

As you might imagine, opinion has entrenched itself on both sides of this issue. Those who believe that EM drives have allowed us to stumble upon some hitherto undiscovered branch of physics seized upon the fact that the NASA paper was peer-reviewed to support their case, while those who believe the mechanism through which the force is generated will eventually be explained by conventional means stuck to their guns. The rest of us who sit on the fence await further developments from either side with interest.

Over at Phys.org they have an interview from the University of Connecticut with [Brice Cassenti], a propulsion expert, which brings his specialist knowledge to the issue. He believes that eventually the results will be explained by conventional means, but explains why the paper made it through peer review and addresses some of the speculation about the device being tested in space. If you are firmly in one of the opposing camps the interview may not persuade you to change your mind, but it nevertheless makes for an interesting read.

If EM drives are of interest, you might find our overview from last year to be an illuminating read. Meanwhile our coverage of the NASA paper should give you some background to this story, and we’ve even had one entered in the Hackaday Prize.

Arm Thrusters, For Underwater Super Powers!

Most of us will have spent the idle hours of our youth while sitting in a room where a teacher was standing at the blackboard explaining iambic pentameter or the Diet of Wurms, daydreaming about the amazing exploits we could have created if only we had an Evil Lair stuffed with all the tools our fertile imaginations demanded. [James Bond] would have had nothing on us, our personal [Q] branch would have ensured we would have had the coolest gadgets on the planet.

As grown-ups we have some of the resources to make this a reality, yet somehow we’ve never made good on the dream. We spend our time creating IoT clocks or novelty electronic Christmas ornaments, and Mr. [Bond] still has a monopoly on the really cool stuff. Fortunately [PeterSripol] has struck a blow on our behalf, because he’s created a pair of arm-mounted underwater thrusters (YouTube, embedded below) that should leave [007] feeling definitely a bit [006.5].

The thrusters themselves came from a Kickstarter purchase that he left on the shelf for a while without an application. Then with only a short time before a trip to Hawaii, he set to work to do something with them, and the arm thrusters were the result.

He makes extensive use of components from the world of radio controlled models, with battery packs and speed controllers mounted in a waterproof food container at his belt, and a pair of handheld microswitch controllers. There is an Arduino which presumably produces the PWM signal, and we are treated to an in-depth look at his waterproofing efforts for the various connectors and switches. After a false start with battery polarity and a cracked impeller housing the device works, and we see it in use on a suitably tropical though not quite sun-kissed beach.

The thrusters appear to work very well, and we’d say they look a lot of fun to use. Sadly the exercise is brought to a halt when a control wire is sucked into a propeller, but we’re sure that’s only a minor setback. We’ve posted the video below the break, take a look.

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Fail of the Week: Pinewood Derby Cheat Fails Two Ways

Would you use your tech prowess to cheat at the Pinewood Derby? When your kid brings home that minimalist kit and expects you to help engineer a car that can beat all the others in the gravity-powered race, the temptation is there. But luckily, there are some events that don’t include the kiddies and the need for parents to assume the proper moral posture. When the whole point of the Pinewood Derby is to cheat, then you pull out all the stops, and you might try building an electrodynamic suspension hoverboard car.

Fortunately for [ch00ftech], the team-building Derby sponsored by his employer is a little looser with the rules than the usual event. Loose enough perhaps to try a magnetically levitating car. The aluminum track provided a perfect surface to leverage Lenz’s Law. [ch00ftech] tried different arrangements of coils and drivers in an attempt to at least reduce the friction between car and track, if not outright levitate it. Sadly, time ran out and physics had others ideas, so [ch00ftech], intent on cheating by any means, tried spoofing the track timing system with a ridiculous front bumper of IR LEDs. But even that didn’t work in the end, and poor [ch00f]’s car wound up in sixth place.

So what could [ch00ftech] had done better? Was he on the right course with levitation? Or was spoofing the sensors likely to have worked with better optics? Or should he have resorted to jet propulsion or a propeller drive? How would you cheat at the Pinewood Derby?


2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which celebrates failure as a learning tool. Help keep the fun rolling by writing about your own failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

Quick Arduino Hack Lets Tach-less Car Display Shift Points

A tachometer used to be an accessory added to the dash of only the sportiest of cars, but now they’re pretty much standard equipment on everything from sleek coupes to the family truckster. If your daily driver was born without a tach, fear not – a simple Arduino tachometer is well within your reach.

The tach-less vehicle in question is [deepsyx]’s Opel Astra, which from the video below seems to have the pep and manual transmission that would make a tach especially useful. Eschewing the traditional analog meter display or even a digital readout, [deepsyx] opted to indicate shift points with four LEDs mounted to a scrap of old credit card. The first LED lights at 4000 RPM, with subsequent LEDs coming on at each 500 RPM increase beyond that. At 5800 RPM, all the LEDs blink as a redline warning.  [Deepsyx] even provides a serial output of the smoothed RPM value, so logging of RPM data is a possible future enhancement.

The project is sensing engine speed using the coil trigger signal – a signal sent from the Engine Control Unit (ECU) which tells one of the ignition coilpacks to fire. The high voltage signal from the coilpack passes on to the spark plug, which ignites the air-fuel mixture in that cylinder. This is a good way to determine engine RPM without mechanical modifications to the car. Just make sure you modify the code for the correct number of cylinders in your vehicle.

Simple, cheap, effective – even if it is more of a shift point indicator than true tachometer, it gets the job done. But if you’re looking for a more traditional display and have a more recent vintage car, this sweeping LED tachometer might suit you more.

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3D Printed R/C Lifeboat

Radio control boats usually bring up thoughts of racing catamarans, or scale sailing yachts. This build takes things in a slightly different direction. A radio controlled lifeboat with a built-in First Person View (FPV) transmitter. [Peter Sripol] used to be one of the awesome folks over at Flite Test. Now he’s gone solo, and has been cranking out some great builds on his YouTube channel. His latest build is a lifeboat loosely based on the totally enclosed lifeboats used on oil tankers and other seafaring vessels.

[Peter] designed the boat in 3D modeling software and printed it on his Lulzbot Taz 6. The files are available on Thingiverse if you want to print your own. The lower hull was printed in two pieces then epoxied together. Peter’s musical build montage goes by fast, proving that he’s just as good editing video as he is scratch-building R/C craft. Along the way he shows us everything from wiring up speed controls to cutting and soldering up a rudder. The final touch on this boat is a micro FPV camera and radio transmitter. As long as the boat is in range, it can be piloted through video goggles.

[Peter’s] boat is destined to be tested on an upcoming trip to Hawaii, so keep an eye on his channel to see how it fares in the monster waves!

A Next-Level Home-Built Flight Simulator

Every hobby needs to have a few people who take it just a little too far. In particular, the aviation hobbies – Radio control flying, FPV multicopter racing, and the like – seem to inspire more than their fair share of hard-core builds. In witness whereof we present this over-the-top home-brew flight simulator.

His wife and friends think he’s crazy, and we agree. But [XPilotSimPro] is that special kind of crazy that it takes to advance the state of the art, and we applaud him for that. A long-time fan of flight simulator games, he was lucky enough to log some time in a real 737 simulator. That seems to be where he caught the DIY bug. The video after the break is a whirlwind tour of the main part of his build, which does not seek to faithfully reproduce any particular cockpit as much as create a plausibly awesome one. Built on a PVC pipe frame with plywood panels, the cockpit is bristling with LCD panels, flight instruments, and bays of avionics that look like they came out of a cockpit. The simulator sits facing a wall with an overhead LCD projector providing views of the outside world. An overhead panel sporting yet more LCD panels and instruments was a recent addition. The whole thing is powered by a hefty looking gaming rig running X-Plane, allowing [XPilotSimPro] to take on any aviation challenge, including landing an Embraer 109 on the deck of the USS Nimitz Aircraft Carrier.

What could be next for [XPilotSimPro]’s simulator? How about adding a little motion control with pneumatics? Or better still, how about using a real 737 cockpit as a simulator?

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Automate the Freight: Robotic Deliveries Are on the Way

Seems like all the buzz about autonomous vehicles these days centers around self-driving cars. Hands-free transportation certainly has its appeal – being able to whistle up a ride with a smartphone app and converting commute time to Netflix binge time is an alluring idea. But is autonomous personal transportation really the killer app that everyone seems to think it is? Wouldn’t we get more bang for the buck by automating something a little more mundane and a lot more important? What about automating the shipping of freight?

Look around the next time you’re not being driven to work by a robot and you’re sure to notice a heck of a lot of trucks on the road. From small panel trucks making local deliveries to long-haul tractor trailers working cross-country routes, the roads are lousy with trucks. And behind the wheel of each truck is a human driver (or two, in the case of team-driven long-haul rigs). The drivers are the weak point in this system, and the big reason I think self-driving trucks will be commonplace long before we see massive market penetration of self-driving cars.

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