Parallax Update Hack Chat

Join us on Wednesday, August 28th at noon Pacific for the Parallax Update Hack Chat with Chip and Ken Gracey!

For a lot of us, our first exposure to the world of microcontrollers was through the offerings of Parallax, Inc. Perhaps you were interested in doing something small and light, and hoping to leverage your programming skills from an IBM-PC or an Apple ][, you chanced upon the magic of the BASIC Stamp. Or maybe you had a teacher who built a robotics class around a Boe-Bot, or you joined a FIRST Robotics team that used some Parallax sensors.

Whatever your relationship with Parallax products is, there’s no doubting that they were at the forefront of the hobbyist microcontroller revolution. Nor can you doubt that Parallax is about a lot more than BASIC Stamps these days. Its popular multicore Propeller chip has been gaining a passionate following since its 2006 introduction and has found its way into tons of projects, many of which we’ve featured on Hackaday. And now, its long-awaited successor, the Propeller 2, is almost ready to hit the market.

The Gracey brothers have been the men behind Parallax from the beginning, with Chip designing all the products and Ken running the business. They’ll be joining us on the Hack Chat to catch us up on everything new at Parallax, and to give us the lowdown on the P2. Be sure to stop be with your Parallax questions, or just to say hi.

join-hack-chatOur Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, August 28 at 12:00 PM Pacific time. If time zones have got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

Go Up A Creek Without A Paddle

Kayaks are a some of the most versatile watercraft around. You can fish from them, go on backpacking trips, or just cruise around your local lake for a few hours. They’re inexpensive, lightweight, don’t require fuel, and typically don’t require a license or insurance to operate. They also make a great platform for a solar-powered boat like this one with only 150 watts of panels and a custom-built motor with parts from an RC airplane.

[William Frasier] built his solar-powered kayak using three solar panels, two mounted across the bow of the boat using pontoons to keep them from dipping into the water, and the other mounted aft. Separating the panels like this helps to prevent all three of them being shaded at once when passing under bridges. They’re all wired in parallel to a 12V custom-built motor which is an accomplishment in itself. It uses custom-turned parts from teak, a rot-resistant wood, is housed in an aluminum enclosure, and uses an RC airplane propeller for propulsion.

Without using the paddles and under full sun, the kayak can propel itself at about 4 knots (7 kmh) which is comparable to a kayak being propelled by a human with a paddle. With a battery, some of the shading problems could be eliminated, and adding an autopilot to it would make it almost 100% autonomous.

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Hackaday Links: October 7, 2018

Ah, crap. We lost a good one, people. [Samm Sheperd] passed away last month. We’ve seen his stuff before, from a plane with a squirrel cage fan, to completely owning a bunch of engineering students by auditing a class. The obit is available as a Google Doc, and there’s a Samm Sheperd Memorial Fund for the Big Lake Youth Camp in Gladstone, Oregon.

FranLab is closing down! Fran is one of the hardware greats, and she’s being evicted. If you’ve got 2000sqft of workshop space in Philly you’d like to spare, you know who to talk to. There will, probably, be a crowdfunding thing going up shortly, and we’ll post a link when it’s up.

The Parallax Propeller is probably one of the most architecturally interesting microcontrollers out there. It’s somewhat famous for being a multi-core chip, and is commonly used in VGA generation, reading keyboards, and other tasks where you need to do multiple real-time operations simultaneously. The Parallax Propeller 2, the next version of this chip, is in the works, and now there’s real silicon. Everything is working as expected, and we might see this out in the wild real soon.

Thought artistic PCBs were just a con thing? Not anymore, I guess. There has been a lot of activity on Tindie with the Shitty Add-Ons with [TwinkleTwinkie] and [Potato Nightmare] releasing a host of very cool badges for your badges. Most of these are Shitty Add-Ons, and there will be an update to the Shitty Add-On spec shortly. It’s going to be backwards-comparable, so don’t worry.

Unnecessary drama!?! In my 3D printing community?!? Yes, it’s true, there was a small tiff over the Midwest RepRap Festival this week. Here’s what went down. You got three guys. John, Sonny, and Steve. Steve owns SeeMeCNC, based in Goshen, Indiana. John worked for SeeMeCNC until this year, and has been the ‘community manager’ for MRRF along with Sonny. Seeing as how the RepRap Festival is the only thing that ever happens in Goshen, Steve wanted to get the ball rolling for next year’s MRRF, so he sent out an email, sending the community into chaos. No, there’s not some gigantic fracture in the 3D printing community, John and Sonny, ‘were just slacking’ (it’s five months out, dudes. plenty of time.), and Steve wanted to get everything rolling. No problem here, just a bunch of unnecessary drama in the 3D printing community. As usual.

The Carbon Fiber Construction Of Large Propellers

Props for your little RC airplane or drone are effectively consumables. They’re made of plastic, they’re cheap, and you’re going to break a lot of them. When you start swinging something larger than 12 inches or so, things start getting expensive. If you’re building gigantic octocopters or big RC planes, those props start adding up. You might not think you can build your own gigantic carbon fiber propellers, but [Tech Ingredients] is here to prove you wrong with an incredible video demonstration of the construction of large propellers

The key ideas behind the build are laid out in a video demonstration for building a single prop. The base begins with a CNC wire cut foam air foil. This foam airfoil is first modified for the attachment point by cutting a plug out of the root of the airfoil which is filled with epoxy.

With the skeleton of the airfoil complete, the build then moves on to laminating the foam core with carbon fiber. The epoxy itself is West Systems Pro-Set laminating epoxy, although we suspect the ubiquitous West Systems epoxy used for all those live-edge ‘river’ coffee tables will also work as well. This epoxy is spread out on a table, the carbon fiber laid over it, and a second layer of carbon fiber (check ‘yo biases!) laid over that. This is wrapped around the foam core, then cured with an electric heating pad.

Of course, this is only a demonstration of making a single blade for a prop. The next trick is turning that single blade into a propeller. This is done with a cleverly machined hub, attached through that epoxy plug placed in the foam core. The results are just as good as any large prop you could buy, and this has the added benefit of being something you made, not bought.

This is really a master class in composite construction, and well worth an hour’s of YouTube viewing. You can check out the intro video below.

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Quadcopter Hardware Gets Classic Lake Bed Test

You’d be hard pressed to find an aircraft that wasn’t designed and tested without extensive use of simulation. Whether it’s the classic approach of using a scale model in a wind tunnel or more modern techniques such as computational fluid dynamics, a lot of testing happens before any actual hardware gets bolted together. But at some point the real deal needs to get a shakedown flight, and historically a favorite testing ground has been the massive dry lake beds in the Western United States. The weather is always clear, the ground is smooth, and there’s nobody for miles around.

Thanks to [James] and [Tyler] at Propwashed, that same classic lake bed approach to real-world testing has now been brought to the world of high performance quadcopter gear. By mounting a computer controlled thrust stand to the back of their pickup truck and driving through the El Mirage dry lake bed in the Mojave Desert, they were able to conduct realistic tests on how different propellers operate during flight. The data collected provides an interesting illustration of the inverse relationship airspeed has with generated thrust, but also shows that not all props are created equal.

The first post in the series goes over their testing set-up and overall procedure. On a tower in the truck’s bed a EFAW 2407 2500kV motor was mounted on a Series 1520 thrust stand by RCBenchmark. This stand connects to the computer and offers a scripted environment which can be used to not only control the motor but monitor variables like power consumption, RPM, and of course thrust. While there was some thought given to powering the rig from the truck’s electrical system, in the end they used Turnigy 6000mAh 4S battery packs to keep things simple.

A script was written for the thrust stand which would ramp the throttle from 0% up to 70% over 30 seconds, and then hold it at that level for 5 seconds. This script was run when the truck was at a standstill, and then repeated with the truck travelling at increasingly faster speeds up to 90 MPH. This procedure was repeated for each of the 15 props tested, and the resulting data graphed to compare how they performed.

The end result was that lower pitch props with fewer blades seemed to be the best overall performers. This isn’t a huge surprise given what the community has found through trial and error, but it’s always good to have hard data to back up anecdotal findings. There were however a few standout props which performed better at high speeds than others, which might be worth looking into if you’re really trying to push the envelope in terms of airspeed.

As quadcopters (or “drones”, if you must) have exploded in popularity, we’re starting to see more and more research and experimentation done with RC hardware. From a detailed electrical analysis of hobby motors to quantifying the latency of different transmitters.

Firing Bullets Through Propellers

Early airborne combat was more like a drive-by shooting as pilot used handheld firearms to fire upon other aircraft. Whomever could boost firepower and accuracy would have the upper hand and so machine guns were added to planes. But it certainly wasn’t as simple as just bolting one to the chassis.

This was during World War I which spanned 1914 to 1918 and the controllable airplane had been invented a mere eleven years before. Most airplanes still used wooden frames, fabric-covered wings, and external cable bracing. The engineers became pretty inventive, even finding ways to fire bullets through the path of the wooden propeller blades while somehow not tearing them to splinters.

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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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