RC Lawn Mower Cuts With Impunity

December 16, 2020 by Lewin Day 19 Comments

Grass is a lovely thing to have, but unfortunately it tends to grow excessively long if left unattended. Obviously, one can use a regular lawn mower, but [Daniel] of [rctestflight] decided to build something remote-control instead. (Video, embedded below.)

To get started, [Daniel] fitted X-acto blades to a brushless outrunner motor, and tested their ability to cut grass. Satisfied with the performance, he built a trailer to tow behind an RC tank mounted to such a setup, with some success. With the concept beginning to bear fruit, he went with a clean sheet design for maximum performance.

The final build relies on an RC rock-crawler chassis, fitted with a brushless motor using field oriented control for maximum torque at low speeds. This allows the RC mower to slowly push through the grass without overwhelming the cutter heads. As for the cutter heads, the final rig has eight motors, each sporting two blades to chop down long field grasses with impunity.

[Daniel] notes that it’s remarkably fun to cut the grass in this way, and is surprised not to have seen more builds in this area. (Editor’s note: he needs to read more Hackaday.) Of course, we’ve seen plenty of autonomous builds, too.

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A Rocket Powered Ejection Seat For Model Aircraft

November 21, 2020 by Lewin Day 4 Comments

As radio control planes don’t typically have human pilots onboard, the idea of installing an ejection seat in one is somewhat frivolous. But that doesn’t mean it wouldn’t be a lot of fun, and [James Whomsley] has set his mind to achieving the task.

The build process is an iterative one, with [James] solving problems step-by-step and testing along the way. The first task was to successfully launch a small action figure and his flight seat vertically in a controlled fashion. After a few attempts, a combination of rocket motors and guide rails were settled upon that could achieve the goal. Next up, a drogue parachute system was designed and tested to stabilize the seat at the height of its trajectory. Further work to come involves handling seat separation and getting the action figure safely back to the ground.

While action figures aren’t alive and the ejection seat serves no real emergency purpose, we can imagine it would be a hit at the local flying field – assuming the parachutes don’t get tangled in someone else’s model. For those interested in the real technology, our own [Dan Maloney] did a great piece on the topic. Video after the break.

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Robust Water-Rocket Launcher Gets The Engineering Just Right

November 5, 2020 by Dan Maloney 7 Comments

Normally when we run across a project that claims to be overengineered, we admit that we get a little excited. Such projects always hold the potential for entertainingly over-the-top designs, materials, and methods. In this case, though, we’ll respectfully disagree with [Zach Hipps] assessment of his remote-controlled soda bottle rocket launcher as “overengineered”. To us, it seems just right.

That’s not to take away from anything accomplished with this build. Indeed, we’re mighty impressed by the completeness of the build, which was intended to create a station for charging and launching air-powered water rockets. The process started with a prototype, built mainly from 3D-printed parts but with a fair selection of workshop scraps to hold it together. This allowed [Zach] to test the geometry of the parts, operation of the mechanism, and how it interfaced with the flange on the necks of 2-liter soda bottles.

Honestly, the prototype was pretty good by itself and is probably where many of us would have stopped, but [Zach] kept going. He turned most of the printed parts into machined aluminum and Delrin, making for a very robust pneumatically operated stand. We’ve got to say the force with which the jaws close around the bottle flange is a bit scary — looks like it could easily clip off a wayward finger. But if he manages to avoid that fate, such a hearty rig should keep [Zach] flying for a long time. Perhaps it could even launch a two-stage water rocket?

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Scratching That Itch

October 31, 2020 by Elliot Williams 11 Comments

I did something silly. I bought a lot of ten “broken” cheesy indoor quadcopters on eBay — to hopefully cobble one working one together and to amuse my son. At this point, I’ve got eight working. The bad news is that they all come with dirt-cheap transmitters that aren’t really conducive to flying at all. They’d be a lot more fun if they could be controlled with a real remote. Enter the hackers.

Most all of the cheap quads are based on one of a handful of radio chipsets, although they use different protocols. An enterprising hacker could conceivably just bundle together this handful of radio modules, and the rest would be a simple matter of software. That’s exactly what Pascal Langer’s DIY Multiprotocol TX and supporting firmware does. This hobby project was so successful that compatible hardware is manufactured by more than a few Chinese companies, and non-geeks have them installed in their radios. The module lets you control virtually anything that uses 2.4 GHz. Of course, I’ve got one of them.

I opened up the cheesy drone’s transmitter, found that it used a popular chipset, and worked through all the different supported protocols that used it. No dice. But the radio module did have nicely labeled SPI lines, so I reached out to Pascal. A couple of Sigrok sessions later, he’d figured out that it was trying to bind on a different channel, I’d recompiled the firmware, and was playing with the drone’s other functions.

I just love a good SPI-sniffing session. sigrok-cli -d fx2lafw -c samplerate=4000000 -P spi:clk=D0:mosi=D1:cs=D2 -A spi="mosi transfer" --continuous | grep A0 | uniq reads the SPI lines, decodes the packets, filters out the commands, and removes duplicates, in real-time. All that’s left to do is wiggle the sticks, mash buttons, and take good notes.

None of this was hard, and certainly none of it was expensive. I got my drones under the control of my fancy-schmancy remote, and have a good foothold into controlling them algorithmically later on thanks to everyone’s previous work on reverse engineering these protocols. Support for DF Drone’s SkyTumbler will be included in the next DIY Multiprotocol TX release, and I spent about four or five pleasant hours on this project. Maybe only a handful of people will stumble on this particular protocol — or maybe it will just be me. I did it mostly just to scratch my own particular itch.

But that’s one way open source works, thrives, and grows. Here’s to you all out there, from the Deviation team, who did a lot of the early drone protocol reverse engineering, to Pascal for the DIY Module, to the Sigrok folks who made the tools accessible for me to piggyback on everyone’s previous work. Keep on hacking!

ESP8266 Does RC Without The Transmitter

October 30, 2020 by Tom Nardi 27 Comments

While the cost of a hobby-grade remote control transmitter has dropped significantly over the last decade or so, even the basic models are still relatively expensive. It’s not such a big deal if you only need to get one for personal use, but for a school to outfit a classroom’s worth of students their own radios, they’d need to have a serious STEM budget.

Which is why [Miharix], himself an educator with a decade of experience, developed a project that leverages the ESP8266 to create affordable RC vehicles that can be controlled with a smartphone’s web browser. There’s a bit of irony at play since the smartphones are more expensive than the RC transmitters would have been; but with more and more school-age kids having their own mobile devices, it takes the cost burden off of the educators. Depending on the age of the students, the teacher would only need to keep a couple of burner phones on hand for student that doesn’t have a device of their own.

A custom PCB makes connections easier for students.

In its fully realized form, the project uses an open hardware board that allows standard RC hobby servos to be connected to the GPIO pins of a ESP-12E module. But if you don’t want to go through the trouble of building the custom hardware, you could put something similar together with an ESP development board. From there it’s just a matter of installing the firmware, which starts up a server providing a touch-based controller interface that’s perfect for a smartphone’s screen.

Since the ESP8266 pops up as an Access Point that client devices can connect to, you don’t even need to have an existing network in place. Or Internet access, for that matter. [Miharix] says that in tests, the range between a common smartphone and the ESP8266 is approximately 85 meters (260 feet), which should be more than enough to get the job done.

In the videos after the break you can see this system being used with an RC car and boat, though the only limit to what you could control with this project is your own imagination.

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Wooden Tank’s Movement Hinges On Hinges

September 9, 2020 by Brian McEvoy 28 Comments

When we first looked at this tank, we thought it was pretty cool. The sides are unpainted 1/2″ (12mm) plywood, so it is not flashy. The dimensions came from Google-fu-ing the heck out of the WWII Hetzer and scaling them to 1:6. What knocks our socks off is how much [Bret Tallent] made use of parts you would find in a hardware store or bicycle shop. He uses twin motors from electric bikes, and the wheels look like replacement shopping cart wheels. The best part is the treads, which are dozens of hinges fastened with pairs of bolts and nylon-insert nuts. Something is reassuring about knowing that a repair to your baby is no further than a bike ride.

We don’t know what started [Bret] on his path to sidewalk superiority, but we suspect he is cooped up like the rest of us and looking to express himself. Mini-Hetzer is not licensed by Power Wheels and never will be, so it probably won’t turn into a business anytime soon. There is a complete gallery starting with an empty plywood base, and the pictures tell the story of how this yard Jäger got to this point. There are plans to add a paintball gun and streaming video, so we’d advise that you don’t mess with the jack-o-lanterns on his block this year. Give his gallery a view and see if you don’t become inspired to cobble something clever from the hardware store too. Then, tell us about it.

Another creative hacker used wood for their tank body and the treads as well. If you like your treaded vehicles functional, we have one meant to taxi small planes over the tarmac.

Building A YouTube Remote Control Worthy Of 2020

August 11, 2020 by Tom Nardi 14 Comments

Back in 2018, [Gryo] built a remote control specifically for watching YouTube videos on his computer. It worked perfectly, but it didn’t quite fit the expectation one has for a modern media remote — it was a bit chunky, the buttons weren’t very responsive, and it didn’t feel as nice as the remotes that ship with consumer streaming devices. Looking to improve on things, he’s recently unveiled a far more svelte version of his scratch built media streaming remote includes a scrollwheel, color feedback, and a UI for customizing how it works.

wireless-YouTube-keyboard-remote-exploded-view

It might not look the part, but technically [Gyro] categorizes his creation as a wireless keyboard since that’s what the operating system sees it as. This makes it easy to use with whatever media playback software or service might be running on the computer, as button presses on the remote are picked up as standard keyboard events. And the software easily sets which key each button on the remote will be associated with.

Inside the 3D printed case there’s a custom PCB that pulls together the ATmega328P, NRF24L01 radio, and TP4056 charger that tops off the 500 mAh Li-Po battery via USB-C. The receiver is also a custom creation, using a second NRF24L01 chip but swapping out the microcontroller for the ATmega32U4.

[Gyro] has done a fantastic job documenting this build in the write-up, and provides everything you need should you want to spin up your own copy. As much as we liked the unique approach used in the first version of the remote, we’ve got to admit this iteration is much more likely to end up sitting on our living room table.

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