Watch This Tiny Dome Auto-open and Close into a Propeller

Careful planning and simulation is invaluable, but it can also be rewarding to dive directly into prototyping. This is the approach [Carl Bugeja] took with his Spherical Folding Propeller design which he has entered into the Open Hardware Design Challenge category of The 2018 Hackaday Prize. While at rest, the folding propeller looks like a small dome attached to the top of a motor. As the motor fires up, centrifugal forces cause the two main halves of the dome to unfold outward where they act as propeller blades. When the motor stops, the assembly snaps shut again.

[Carl] has done some initial tests with his first prototype attached to a digital scale as a way of measuring thrust. The test unit isn’t large — the dome is only 1.6 cm in diameter when folded — but he feels the results are promising considering the small size of the props and the fact that no simulation work was done during the initial design. [Carl] is looking to optimize the actual thrust that can be delivered, now that it has been shown that his idea of a folding dome works as imagined.

Going straight to physical prototyping with an idea can be a valid approach to early development, especially nowadays when high quality components and technologies are easily available even to hobbyists. Plus it can be great fun! You can see and hear [Carl]’s prototype in the short video embedded below.

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3D Printed Propellers Take to the Skies

In the world of drones, propeller choice is key to performance. Selecting the right props can have a major effect on things like flight time, vibration, and a whole host of other factors. Thinking it might be fun to experiment, [RCLifeOn] decided to 3D print some props and head out for a flight.

The props are a fairly simple 3-bladed design, which were printed in both PETG and PLA. No major difference is noted between the two materials, and the quadcopter under test is able to fly with either. It was noted that the props perform particularly poorly in a crash, with all props failing even in the softest of crashes. We would recommend some eye (and body) protection when spinning these props up for the first time.

If you’re keen to try them out yourself, the STL file can be had here. The video notes that when printing 4 props, 2 must be reversed in the Y-axis to print a counter-rotating set of 4. The instructions used for creating propellers in Fusion3D are available here.

It’s a worthy experiment, and something we’d like to see more of. With a 3D printer, it’s possible to experiment with all manner of propeller designs, and we’d love to see the best and worst designs that are still capable of flight. We’ve also seen 3D printed props before, like this effort from [Anton].

3D Printed Airplane Engine Runs on Air

One of the most important considerations when flying remote-controlled airplanes is weight. Especially if the airplane has a motor, this has a huge potential impact on weight. For this reason, [gzumwalt] embarked on his own self-imposed challenge to build an engine with the smallest weight and the lowest parts count possible, and came away with a 25-gram, 8-part engine.

The engine is based around a single piston and runs on compressed air. The reduced parts count is a result of using the propeller axle as a key component in the engine itself. There are flat surfaces on the engine end of the axle which allow it to act as a valve and control its own timing. [gzumwalt] notes that this particular engine was more of a thought experiment and might not actually produce enough thrust to run an airplane, but that it certainly will spark up some conversations among RC enthusiasts.

The build is also one of the first designs in what [gzumwalt] hopes will be a series of ever-improving engine designs. Perhaps he should join forces with this other air-powered design that we’ve just recently featured. Who else is working on air-powered planes? Who knew that this was a thing?

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Hackaday Links: July 16, 2017

[Carl Bass] has joined the board at Formlabs. This is interesting, and further proof that Print The Legend is now absurdly out of date and should not be used as evidence of anything in the world of 3D printing.

Here’s something cool: a breadboardable dev board for the Parallax Propeller.

Finally, after years of hard work, there’s a change.org petition to stop me. I must congratulate [Peter] for the wonderful graphic for this petition.

Want some flexible circuits? OSHPark is testing something out. If you have an idea for a circuit that would look good on Kapton instead of FR4, shoot OSHPark an email.

SeeMeCNC has some new digs. SeeMeCNC are the creators of the awesome Rostock Max 3D printer and hosts of the Midwest RepRap Festival every March. If you’ve attended MRRF, you’re probably aware their old shop was a bit on the small side. As far as I can figure, they’ll soon have ten times the space as the old shop. What does this mean for the future of MRRF? Probably not much; we’ll find out in February or something.

Rumors of SoundCloud’s impending demise abound. There is some speculation that SoundCloud simply won’t exist by this time next year. There’s a lot of data on the SoundCloud servers, and when it comes to preserving our digital heritage, the Internet Archive (and [Jason Scott]) are the go-to people. Unfortunately, it’s going to cost a fortune to back up SoundCloud, and it would be (one of?) the largest projects the archive team has ever undertaken. Here’s your donation link.

If you’re looking for a place to buy a Raspberry Pi Zero or a Pi Zero W, there’s the Pi Locator, a site that pings stores and tells you where these computers are in stock. Now this site has been expanded to compare the price and stock of 2200 products from ModMyPi, ThePiHut, Pi-Supply, and Kubii.

Helix Display Brings Snake Into Three Dimensions

Any time anyone finds a cool way to display in 3D — is there an uncool way? — we’re on board. Instructables user [Gelstronic]’s method involves an array of spinning props to play the game Snake in 3D.

The helix display consists of twelve props, precisely spaced and angled using 3D-printed parts, each with twelve individually addressable LEDs. Four control groups of 36 LEDs are controlled by the P8XBlade2 propeller microcontroller, and the resultant 17280 voxels per rotation are plenty to produce an identifiable image.

In order to power the LEDs, [Gelstronic] used wireless charging coils normally used for cell phones, transferring 10 W of power to the helix array.  A brushless motor keeps things spinning, while an Arduino controls speed and position via an encoder. All the links to the code used are found on the project page, but we have the video of the display in action is after the break.

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KFC Winged Aircraft Actually Flies

[PeterSripol] has made an RC model airplane but instead of using normal wings he decided to try getting it to fly  using some KFC chicken buckets instead. Two KFC buckets in the place of wings were attached to a motor which spins the buckets up to speed. With a little help from the Magnus effect this creates lift.

Many different configurations were tried to get this contraption off the ground. They eventually settled on a dual prop setup, each spinning counter to each other for forward momentum. This helped to negate the gyroscopic effect of the spinning buckets producing the lift. After many failed build-then-fly attempts they finally got it in the air. It works, albeit not to well, but it did fly and was controllable. Perhaps with a few more adjustments and a bit of trial and error someone could build a really unique RC plane using this concept.

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Propeller Backpack for Lazy Skiers

At first glance, it looks eerily similar to Inspector Gadget’s Propeller Cap, except it’s a backpack. [Samm Sheperd] built a Propeller Backpack (video, embedded after the break) which started off as a fun project but almost ended up setting him on fire.

Finding himself snowed in during a spell of cold weather, he found enough spare RC and ‘copter parts to put his crazy idea in action. He built a wooden frame, fixed the big Rimfire 50CC outrunner motor and prop to it, slapped on a battery pack and ESC, and zip-tied it all on to the carcass of an old backpack.

Remote control in hand, and donning a pair of Ski’s, he did a few successful trial runs. It looks pretty exciting watching him zip by in the snowy wilderness. Well, winter passed by, and he soon found himself in sunny California. The Ski’s gave way to a bike, and a local airfield served as a test track. He even manages to put in some exciting runs on the beach. But the 10S 4000 mAH batteries seem to be a tad underpowered to his liking, and the motor could do with a larger propeller. He managed to source a 12S 10,000 mAH battery pack, but that promptly blew out his Aerostar ESC during the very first static trial.

He then decided to rebuild it from ground up. A ten week welding course that he took to gain some college credits proved quite handy. He built a new TiG welded Aluminium frame which was stronger and more lightweight than the earlier wooden one. He even thoughtfully added a propeller safety guard after some of his followers got worried, although it doesn’t look very effective to us. A bigger propeller was added and the old burnt out ESC was replaced with a new one. It was time for another static trial before heading out in to the wide open snow again. And that’s when things immediately went south. [Samm] was completely unaware as the new ESC gloriously burst in to flames (8:00 into the third video), and it took a while for him to realize why his video recording friend was screaming at him. Check out the three part video series after the break to follow the story of this hack. For a bonus, check out the 90 year old gent who stops by for a chat on planes and flying (8:25 in the third video).

But [Samm] isn’t letting this setback pin him down. He’s promised to take this to a logical finish and build a reliable, functional Propeller Backpack some time soon. This isn’t his first rodeo building oddball hacks. Check out his experiment on Flying Planes With Squirrel Cages.

We seem to be catching a wave of wind-powered transportation hacks these days. Hackaday’s own [James Hobson] spent time in December on a similar, arguably safer, concept. He attached ducted fans to the back of a snowboard. We like this choice since flailing limbs won’t get caught in these types of fans.

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