Acoustic Drone Detection On The Cheap With ESP32

March 23, 2026 by Tyler August 16 Comments

We don’t usually speculate on the true identity of the hackers behind these projects, but when [TN666]’s accoustic drone-detector crossed our desk with the name “Batear”, we couldn’t help but wonder– is that you, Bruce? On the other hand, with a BOM consisting entirely of one ESP32-S3 and an ICS-43434 I2S microphone, this isn’t exactly going to require the Wayne fortune to pull off. Indeed, [TN666] estimates a project cost of only 15 USD, which really democratizes drone detection.

It’s not a tuba– Imperial Japanese aircraft detector being demonstrated in 1932. Image Public Domain via rarehistoricalphotos.com

The key is what you might call ‘retrovation’– innovation by looking backwards. Most drone detection schema are looking to the ways we search for larger aircraft, and use RADAR. Before RADAR there were acoustic detectors, like the famous Japanese “war tubas” that went viral many years ago. RADAR modules aren’t cheap, but MEMS microphones are– and drones, especially quad-copters, aren’t exactly quiet. [TN666] thus made the choice to use acoustic detection in order to democratize drone detection.

Of course that’s not much good if the ESP32 is phoning home to some Azure or AWS server to get the acoustic data processed by some giant machine learning model. That would be the easy thing to do with an ESP32, but if you’re under drone attack or surveillance it’s not likely you want to rely on the cloud. There are always privacy concerns with using other people’s hardware, too. [TN666] again reached backwards to a more traditional algorithmic approach– specifically Goertzel filters to detect the acoustic frequencies used by drones. For analyzing specific frequency buckets, the Goertzel algorithm is as light as they come– which means everything can run local on the ESP32. They call that “edge computing” these days, but we just call it common sense.

The downside is that, since we’re just listening at specific frequencies, environmental noise can be an issue. Calibration for a given environment is suggested, as is a foam sock on the microphone to avoid false positives due to wind noise. It occurs to us the sort physical amplifier used in those ‘war tubas’ would both shelter the microphone from wind, as well as increase range and directionality.

[TN] does intend to explore machine learning models for this hardware as well; he seems to think that an ESP32-NN or small TensorFlow Lite model might outdo the Goertzel algorithm. He might be onto something, but we’re cheering for Goertzel on that one, simply on the basis that it’s a more elegant solution, one we’ve dived into before. It even works on the ATtiny85, which isn’t something you can say about even the lightest TensorFlow model.

Thanks to [TN] for the tip. Playboy billionaire or not, you can send your projects into the tips line to see them some bat-time on this bat-channel.

How Long Can A Quadcopter Drone Fly On Just Solar?

March 20, 2026 by Maya Posch 34 Comments

The final second prototype flying. (Credit: Luke Maximo Bell, YouTube)

The dream of fully powering everything from aircraft to cars on just the power generated from solar panels attached to the machine remains a tempting one, but always seems to require some serious engineering including putting the machine on a crash diet. The quadcopter that [Luke Maximo Bell] tried to fly off just solar power is a good case in point, as the first attempt crashed after three minutes and wrecked its solar panels. Now he’s back with a second attempt that ought to stay airborne for as long as the sun is shining.

Among the flaws with the first prototype were poor support for the very thin and fragile PV panels, requiring much better support on the carbon fiber frame of the drone. To support the very large solar array, the first drone’s arms were made to be very long, but this interfered with maneuvering, so the second version got trimmed down and the array raised above the frame. This saved 70 grams of weight from the shortened tubs, which could then be added to the new panel supports.

After an initial test flight resulted in a crash when the PV output dropped, the need for a small battery buffer was clear, so this was added, along with a reduction of the array to 4×7 panels to get the same 20V as the battery. The array also had to be reinforced, as the thin array was very wobbly in addition to making it impossible to fly with any significant wind.

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Creating The World’s Most Efficient Quadcopter Drone

February 18, 2026 by Maya Posch 12 Comments

Keeping an eye on remaining battery charge. (credit: Luke Maximo Bell, YouTube)

Although not a typical focus of people who fly quadcopter drones for a hobby or living, endurance flying has a certain appeal to it for the challenge it offers. Thus, as part of his efforts to collect all the world records pertaining to quadcopter drones, [Luke Maximo Bell] has been working on a design that would allow him to beat the record set by SiFly Aviation at 3 hours and 11 minutes.

By using knowledge gained from his PV solar-powered quadcopter, [Luke] set about to take it all a few steps further. The goal was to get as much performance out of a single Watt, which requires careful balancing of weight, power output and many other parameters.

Crucial is that power usage goes up drastically when you increase the RPM of the propellers, ergo massive 40″ propellers were picked to minimize the required RPM to achieve sufficient lift, necessitating a very large, but lightweight frame.

The battery packs are another major factor since they make up so much of the weight. By picking high-density Tattu batteries and stripping these down even more this was optimized for as well, before even the wire gauge of the power wires running to the motors were investigated to not waste a single Watt or gram.

All of this seems to have paid off, as a first serious test flight resulted in a 3 hour, 31 minutes result, making it quite feasible that [Luke] will succeed with his upcoming attempt at the world’s longest flying electric multirotor record. Another ace up his sleeve here is that of forward movement as well as wind provides effectively free lift, massively reducing power usage and possibly putting the 4 hour endurance score within easy reach.

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Building A Flying Blended Wing Body Aircraft Prototype

December 17, 2025 by Maya Posch 16 Comments

Anyone with an inkling of interest in super-sized remote control aircraft probably has at least seen some of the mind-blowing projects that [Ramy RC] has worked on over the years, with examples like the ongoing Airbus A380-800 build approaching the size of a full-sized business jet. That said, they recently got the offer to build a flying prototype of the Natilus Horizon, a blended wing body (BWB) aircraft that’s currently being developed into a full-sized production aircraft.

Suffice it to say that BWB RC aircraft isn’t something that they have built before, but as co-founder of Natilus, [Aleksey Matyushev], explains, they want to prove in this manner that building scale prototypes of future production aircraft is not nearly as complex as it’s often made out to be. Meaning that even two blokes in a shed as is the case here should be able to pull it off.

Natilus was founded in 2016 amidst strongly rising interest in these BWB aircraft designs that may one day threaten today’s tubes-with-wings. Their Kona design would be the cargo version and this Horizon prototype that [Ramy RC] is building the passenger version.

In this first video of two total, we can see the CAD project of the prototype and how the basic aircraft structure is being constructed out of carbon fiber composite, wood and foam. To this the engine nacelles, landing gear and wings are mounted, readying it for its maiden flight. The Natilus engineers have previously done all the simulations that should mean that it’ll fly like a glider, but we will have to wait until the next video to see whether that is the case.

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Magnus Effect Drone Flies, Looks Impossible

November 30, 2025 by Bryan Cockfield 21 Comments

By now we’re all familiar with the quad-rotor design most popular among modern drones, and of course there are many variants using more or less propellers and even fixed-wing drones that can fly autonomously. We’ve even seen drones that convert from rotorcraft to fixed-wing mid flight. But there are even more esoteric drones out there that are far more experimental and use even more bizarre wing designs that look like they shouldn’t be able to fly at all. Take [Starsistor]’s latest design, which uses a single motor and an unconventional single off-center wing to generate lift.

This wing, though, is not a traditional foil shape typically found on aircraft. It uses the Magnus effect to generate lift. Briefly, the Magnus effect is when lift is generated from a spinning object in a fluid. Unlike other Magnus effect designs which use a motor to spin a cylinder, this one uses a design inspired by Savonius wind turbines where a wing is free to rotate around a shaft. A single propeller provides a rotational force to the craft, allowing this off-center wing to begin spinning and generating lift. The small craft was able to sustain several flights but was limited due to its lack of active control.

[Starsistor] went through a number of iterations before finally getting this unusual craft to fly. His first designs did not have enough rotational inertia and would flip over at speed, which was fixed by moving the propeller further away from the center of the craft. Eventually he was able to get a working design to prove his conceptual aircraft, and we hope to see others from him in the future.

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Using Multiple Quadcopters To Efficiently Lift Loads Together

November 16, 2025 by Maya Posch 7 Comments

Much like calling over a buddy or two to help with moving a large piece of furniture and pivot it up a narrow flight of stairs, so too can quadcopters increase their carrying capacity through the power of friendship and cooperation. However, unless you want to do a lot of yelling at your mates about when to pivot and lift, you’d better make sure that your coordination is up to snuff. The same is true with quadcopters, where creating an efficient coordination algorithm for sharing a load is far from easy and usually leads to fairly slow and clumsy maneuvering.

Simplified overview of the motion planner by Sihao Sun et al.

Recently. researchers at the Technical University of Delft came up with what appears to be a quite efficient algorithm for this purpose. In the demonstration video below, it’s easy to see how the quadcopters make short work of even convoluted obstacles while keeping themselves and their mates from getting tangled.

The research by [Sihao Sun] et al. appears in Science Robotics (preprint), in which they detail their trajectory-based framework and its kinodynamic motion planner. In short, this planner considers the whole-body dynamics of the load, the cables, and the quadcopters. An onboard controller for each quadcopter is responsible for translating the higher-level commands into specific changes to its rotor speeds and orientation.

Along with tests of its robustness to various environmental factors, such as wind, the researchers experimented with how many simultaneous quadcopters could work together with their available computing capacity. The answer, so far, is nine units, though they think that the implementation can be further optimized.

Of course, sometimes you just want to watch synchronized drones.

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EVTOL For Everyone

November 15, 2025 by Tyler August 14 Comments

While most of the world’s venture capital is off chasing anything with “AI” in the name in what many think looks increasingly like an inflated spherical film of soap molecules, in aviation all the hot money is betting on eVTOL: electric vertical take off and landing.

What if you want to get in on the eVTOL game but don’t have (or want) billionaire backing? Long-time contributor [spiritplumber] demonstrates how to do it on the cheap, with a low-cost quadcopter and a foam wing called Lift5.

Most eVTOL isn’t just quadcopters, after all — multirotors are great for playing with in the back yard, but their thrust-based lift makes for short range, and the engine-out options are all bad. Add a wing, and you can get that sweet, sweet dynamic lift. Add an extra, forward facing motor, and you can get thrust in the direction you need it most. That’s what [spiritplumber] is doing here: strapping a foam wing to a cheap quadcopter. Specifically, his custom frame for an Eiele F120 drone kit.You can see it in action in the demo video embedded below.

The wing and its forward thrust motor are equipped with its own speed controller, so the concept should be adaptable to just about any little drone. Quadcopter flight computers are mostly going to be able to compensate for the added lift and thrust automatically, which is neat, considering that these forces would require some bizarre headwind/updraft very unlikely to be found in nature.

Now the wing does add a lot of drag during the lift phase, to be sure, so [spiritplumber] is working on folding or tilting it out of the way, but that version is apparently inordinately fond of trees. Once the control issues are worked out you’ll likely see it on his site and YouTube channel Robots Everywhere.

[spiritplumber] has been contributing hacks here at least since 2009, when he showed us how to make a Macbook right click.

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