Active Aero For A Radio Control Car

January 3, 2021 by Lewin Day 12 Comments

Motorsport became obsessed with aerodynamics in the middle of the 20th century. Moving on from simple streamlined shapes, designers aimed to generate downforce with wing elements in order to get more grip between the tyres and the track. This culminated in the development of active aero, where wing elements are controlled by actuators to adjust the downforce as needed for maximum grip and minimum drag. Recently, [Engineering After Hours] decided to implement the technology on his Traxxas RC car.

The system consists of a simple multi-element front wing, chosen for its good trade-off between downforce and drag. The wing is mounted to a servo, which varies the angle of attack as the car’s pitch changes, as detected by a gyroscope. As the car pitches up during acceleration, the angle of the wing is increased to generate more downforce, keeping the nose planted.

The basic concept is sound, though as always, significant issues present themselves in the implementation. Small bumps cause the system to over-react, folding the wing under the front wheels. Additionally, the greater front downforce caused over-steer, leading to the install of a rear wing as well for better aero balance.

Regardless of some hurdles along the way, it’s clear the system has potential. We look forward to the next build from [Engineering After Hours], which promises to mimic the fan cars of the 70s and 80s. If you’re looking to improve aero on your full-size car, we’ve got a guide to that too. Video after the break.

Continue reading “Active Aero For A Radio Control Car” →

RC Starship Perfects Its Skydiving Routine

December 13, 2020 by Tom Nardi 12 Comments

There’s a good chance you already saw SpaceX’s towering Starship prototype make its impressive twelve kilometer test flight. While the attempt ended with a spectacular fireball, it was still a phenomenal success as it demonstrated a number of concepts that to this point had never been attempted in the real world. Most importantly, the “Belly Flop” maneuver which sees the 50 meter (160 foot) long rocket transition from vertical flight to a horizontal semi-glide using electrically actuated flight surfaces.

Finding himself inspired by this futuristic spacecraft, [Nicholas Rehm] has designed his own radio controlled Starship that’s capable of all the same aerobatic tricks as the real-thing. It swaps the rocket engines for a pair of electric brushless motors, but otherwise, it’s a fairly accurate recreation of SpaceX’s current test program vehicle. As you can see in the video after the break, it’s even able to stick the landing. Well, sometimes anyway.

Just like the real Starship, vectored thrust is used to both stabilize the vehicle during vertical ascent and help transition it into and out of horizontal flight. Of course, there are no rocket nozzles to slew around, so [Nicholas] is using servo-controlled vanes in the bottom of the rocket to divert the airflow from the motors. Servos are also used to control the external control surfaces, which provide stability and a bit of control authority as the vehicle is falling.

As an interesting aside, Internet sleuths looking through pictures of the Starship’s wreckage have noted that SpaceX appears to be actuating the flaps with gearboxes driven by Tesla motors. The vehicle is reportedly using Tesla battery packs as well. So while moving the control surfaces on model aircraft with battery-powered servos might historically have been a compromise to minimize internal complexity, here it’s actually quite close to the real thing.

Unfortunately, the RC Starship made a hard landing of its own on a recent test flight, so [Nicholas] currently has to rebuild the craft before he can continue with further development. We’re confident he’ll get it back in the air, though it will be interesting to see whether or not he’s flying before SpaceX fires off their next prototype.

Continue reading “RC Starship Perfects Its Skydiving Routine” →

A Walking Rover Destined Explore Your Fridge Door

December 10, 2020 by Danie Conradie 7 Comments

It’s usually the simple ideas that sprout bigger ones, and this was the case when we saw [gzumwalt]’s single-motor walking robot crawling up a fridge door with magnets on its feet. (Video, embedded below.)

The walking mechanism consists of an inner foot and two outer feet, connected by three sets of rotating linkages, driven by a single geared motor. The feet move in a leapfrog motion, in small enough steps that the center of mass always stays inside the foot area, which keeps it from tipping over. Besides the previously mentioned ability to crawl around on a vertical magnetic surface, it’s also able to crawl over almost any obstacle shorter than its step length. A larger version should also be able to climb stairs.

As shown, this robot can only travel in a straight line, but this could be solved by adding a disc on the bottom of the inner foot to turn the robot when the outer feet are off the surface. Add some microswitch feelers and an Arduino, and it can autonomously explore your fridge without falling off. Maybe we’ll get around to building it ourselves, but be sure to drop us a tip if you beat us to it!

[gzumwalt] is a master of 3D printed devices like a rigid chain and a domino laying robot. The mechanism for this robot was inspired by one design from [thang010146]’s marvelous video library of mechanisms.

Continue reading “A Walking Rover Destined Explore Your Fridge Door” →

3D Printed Rigid Chain Mechanism

December 8, 2020 by Danie Conradie 34 Comments

One of the major advantages of 3D printing is the ability to quickly test and then iterate on mechanical designs. [gzumwalt] does a lot of this, and has recently been working on various versions of a rigid chain mechanism. (Video, embedded below.)

A rigid-chain mechanism is one way of fitting a long beam into a small box. It works similar to a zipper, meshing two separate “chains” with specially teeth designed to form a rigid beam. Due to clearances between the teeth, the beam tends to be a bit floppy. [gzumwalt] made various sizes of the mechanism, and also reduced the clearances on later versions to reduce the flop. He also integrated it into a cool “snake in a basket” automaton (second video below) by adding a reversible gearbox and a binary snap-action switch.

One possible use for this type of mechanism is for autonomously assembling long structures in space, as one of the 2017 Hackaday Prize finalist projects, ZBeam, proposed.

[gzumwalt] has not made the files available for download yet, but you can keep and eye on his Instructables pages for updates. He got a number of fascinating 3D printed devices already available, like a domino laying machine or a WiFi controlled rover.

Continue reading “3D Printed Rigid Chain Mechanism” →

Tiny Chain-Link Fence Made With Hand-Cranked Brilliance

December 6, 2020 by Danie Conradie 24 Comments

Chain link fences are woven with a mechanism that is almost hypnotic to watch, so [Levsha] decided to build his own tiny hand-crank tabletop version to make tiny copper wire fences.

Chain link consist of a series of wires bent and woven in a zigzag pattern. The zigzag bends are made by winding the wire around a rotating flat plate inside a stationary tube with a spiral slot in the side to keep the spacing of the bends consistent. [Levsha]’s version is roughly 1/10 scale of the real thing, and only does the bending and winding parts. Linking the bent wire together is up to the operator. All the components were machined on a lathe and CNC router, and beautifully finished and assembled on a wood base. The hardest part was the tube with the spiral slot, which took a few attempts to get right. [Levsha] initially tried to use steel wire, but it was too stiff and caused the winding mechanism to lock up. 0.4 mm copper wire turned out to be the best choice.

Although there is no practical use for this device that we can see, the craftsmanship is excellent, and it is one of those videos that reminds us how badly we want some machine tools.

Fine attention to detail is really what makes videos like this enjoyable to watch. Wee seen a few other such project, like a beautiful scratch-built lathe, or a pneumatic powered drone that can’t fly.

Continue reading “Tiny Chain-Link Fence Made With Hand-Cranked Brilliance” →

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.

Continue reading “A Rocket Powered Ejection Seat For Model Aircraft” →

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.

Continue reading “ESP8266 Does RC Without The Transmitter” →