Why Not Build Your Quadcopter Around An Evaluation Board?

Quadcopters are flying machines. Traditionally, that would mean you’d optimize the design for lightweight and minimum drag, and you’d do everything in a neat and tidy fashion. The thing is, brushless motors and lithium batteries are so power-dense that you really needn’t try so hard. A great example of that is this barebones quadcopter build from [hebel23] all the way back in 2015.

The build is based around the STM32F4 Discovery Board, which [hebel23] scored as a giveaway at Electronica in Munich way back when. It’s plopped on top of a bit of prototyping board so it can be hooked up to the four controllers driving the motors at each corner. The frame of the quadcopter similarly uses cheap material, in the form of alloy profiles left over from an old screen door. Other equipment onboard includes a GY-273 electronic compass module, a MPU6050 3-axis gyroscope and accelerometer to keep the thing on the straight and level, and the Fly Sky R9B RC receiver for controlling the thing.

It might look crude, but it gets off the ground just fine. We’ve seen quadcopters using the STM32 in more recent years with more refined designs, but there’s something amusingly elegant about lacing one together with an evaluation board and some protoboard in the middle. If you’re working on your own flying projects, don’t hesitate to notify the tipsline!

New Quadcopter Speed World Record Set At Nearly 500 Km/h

Making a quadcopter go fast would seem to be quite simple: just strap on powerful motors, aim the quadcopter roughly at where you want it to go fast, and let ‘er rip. Because of aerodynamics and other pesky physical laws there are a few complications to this, of course, but this didn’t deter [Luke Bell] and his father [Mike Bell] from nailing the Guinness World Record for remote-controlled quadcopters on April 21, 2024. During the official run, a top speed of 480.23 km/h was recorded, making it considerably faster than the first version they made, which hit a measly 400 km/h.

For this second iteration of the ‘got to go fast’ quadcopter, the design was scaled up, with more powerful motors and associated electronics added. Naturally, when you’re pushing brushless motors and their ESCs to their limits, stuff can get a bit hot due to the immense currents flowing through the system. This resulted in a number of battery, wire and other fires. Fortunately, the worrying aspect of in-flight stability got addressed pretty well courtesy of a professional drone trainer, and ultimately the world record attempt went off without a hitch.

An endurance test was also attempted, which reached 7.5 km at 180 km/h, and with the clear canopy in from of the camera removed, visual performance was pretty stunning, while still easily reaching 400 km/h. This might make it the perfect high-speed chase camera system.

Thanks to [Craig] for the tip.

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ESP-Drone: Building An ESP32-Based Quadcopter For Not Much Cash

What’s the cheapest quadcopter you can build? As [Circuit Digest] demonstrates with their variant of the ESP-Drone project by Espressif, you only need a minimum of parts: an ESP32 MCU, an inertial measurement unit (IMU) such as the MPU6050, and four MOSFETs to drive the brushless DC motors. As the PCB also forms the structural frame and landing struts for the quadcopter, not even a 3D printer is needed. All told, [Circuit Digest] figures the total BOM comes in at around 1,000 Indian Rupees, or about $12 USD.

The fully assembled ESP-Drone flying around. (Credit: Circuit Digest)
The fully assembled ESP-Drone flying around. (Credit: Circuit Digest)

While this [Circuit Digest] project provides basic IMU functionality, the Espressif project also has a few expansion boards detailed on its hardware page, depending on the base model of the mainboard you pick. The [Circuit Digest] project follows the ESPlane-V2-S2 version with no expansion boards, but the ESP32-S2-Drone V1.2 mainboard can be extended with position-hold, pressure and compass modules, as well as custom boards.

As a derivative of the Bitcraze Crazyflie project, the ESP-Drone firmware also supports the rather nifty cfclient software for remote monitoring, logging and control. This may also be in the [Circuit Digest] firmware, but wasn’t listed among the features.

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A Deep Dive Into Quadcopter Controls

In the old days, building a quadcopter or drone required a lot of hacking together of various components from the motors to the batteries and even the control software. Not so much anymore, with quadcopters of all sizes ready to go literally out-of-the-box. While this has resulted in a number of knock-on effects such as FAA regulations for drone pilots, it’s also let us disconnect a little bit from the more interesting control systems these unique aircraft have. A group at Cornell wanted to take a closer look into the control systems for drones and built this one-dimensional quadcopter to experiment with.

The drone is only capable of flying in one dimension to allow the project to more easily fit into the four-week schedule of the class, so it’s restricted to travel along a vertical rod (which also improves the safety of the lab).  The drone knows its current position using an on-board IMU and can be commanded to move to a different position, but it first has to calculate the movements it needs to make as well as making use of a PID control system to make its movements as smooth as possible. The movements are translated into commands to the individual propellers which get their power from a circuit designed from scratch for this build.

All of the components of the project were built specifically for this drone, including the drone platform itself which was 3D printed to hold the microcontroller, motors, and accommodate the rod that allows it to travel up and down. There were some challenges such as having to move the microcontroller off of the platform and boosting the current-handling capacity of the power supply to the motors. Controlling quadcopters, even in just one dimension, is a complex topic when building everything from the ground up, but this guide goes some more of the details of PID controllers and how they help quadcopters maintain their position.

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Exploring Ground-Effect With A Quadcopter

The ground-effect (GE) refers to the almost mystical property where the interaction of the airflow around an aircraft’s wing and the ground massively increases efficiency due to the reduction of lift-dependent drag, perhaps best demonstrated by the Soviet Lun-class “ekranoplans” of the 1980s and 90s. Interestingly, this principle also applies to rotary aircraft, which led the [rctestflight] YouTube channel to wonder what would happen if a quadcopter were to be adapted for GE.

As noted on the Wikipedia entry for Ground-effect vehicle (GEV), it’s essential to have some kind of forward motion. With a rotorcraft like a helicopter or quadcopter this motion is already provided by the spinning propeller, which makes it noticeably easier to get the aircraft into the ground-effect. operating mode. Following the notion that the GE becomes noticeable at an altitude that’s dependent on the length of the aircraft’s wings, this got translated into putting the largest propellers available on the custom inverted-prop (to put them lower to the ground) quadcopter, to see what effect this would have on the quadcopter’s performance. As demonstrated by the recorded current drawn (each time with a fully charged battery), bigger is indeed better, and the GE effect is indeed very noticeable for a quadcopter.

Getting a usable GEV out of the basic inverted-prop quadcopter required some more lateral thinking, however, as it was not very easy to control this low to the ground. Here following design cues from skirtless hovercraft designs helped a lot, essentially drawing on the Coandă effect. Although this improved performance, at this point the quadcopter had been fitted with a fifth propeller for propulsion and was skidding about more like a skirtless hovercraft and less of a quadcopter.

Although great for scaring the living daylights out of unsuspecting water-based wildlife, what this unfortunately demonstrates is that GEVs are still hard, no matter which form they take. At the very least it does make for an excellent introduction into various aspects of aerodynamics.

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Hefty 3D Printed Quadcopter Meets Nasty End

You can readily buy all kinds of quadcopters off the shelf these days, but sometimes it’s more fun to build your own. [Michael Rechtin] did just that, with a hefty design of his own creation.

The build is an exploration of all kinds of interesting techniques. The frame itself uses generative design techniques to reduce weight while maintaining strength, while the motors themselves make heavy use of 3D-printed components. The design is modular and much of it slots together, too, and it uses a homebrewed flight controller running dRehmflight. It draws 2.5 kW from its lithium polymer batteries and weighs over 5 kg.

The DIY ethos led to some hurdles, but taught [Michael] plenty along the way. Tuning the PID control loop posed some challenges, as did one of the hand-wound motors being 5% down on thrust.  Eventually, though, the quad flew well enough to crash into a rectangular gate, before hitting the ground. Any quad pilot will tell you that these things happen. Drilling into the quad with a battery still inside then led to a fire, which did plenty of further damage.

[Michael’s] quad doesn’t appear to be specifically optimized to any one task, and it’s easy to see many ways in which it could be lightened or otherwise upgraded. However, as a freeform engineering thinking exercise, it’s interesting to watch as he tackles various problems and iteratively improves the design. Video after the break.

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Hackaday Podcast 130: Upside Down 3D-Printer, Biplane Quadcopter, Gutting A Calculator Watch, And GitHub CoPilot

Hackaday editors Elliot Williams and Mike Szczys get charged up on the best hacks the week had to offer. The 3D printer design gods were good to us, delivering an upside-down FDM printer and a hack that can automatically swap out heated beds for continuous printing. We look at a drone design that builds vertical wings into the frame of a quadcopter — now when it tips on its side it’s a fixed-wing aircraft! We chew the artificially-intelligent fat about GitHub CoPilot’s ability (or inability?) to generate working code, and talk about the firm future awaiting solid state batteries.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (60 MB or so.)

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