Quadcopter Hardware Gets Classic Lake Bed Test

August 1, 2018 by Tom Nardi 6 Comments

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.

Casting Tour-De-Force Results In Swashplate For Scale Helicopter

July 5, 2018 by Dan Maloney 21 Comments

While quadcopters seem to attract all the attention of the moment, spare some love for the rotary-wing aircraft that started it all: the helicopter. Quads may abstract away most of the aerodynamic problems faced by other rotorcraft systems through using software, but the helicopter has to solve those problems mechanically. And they are non-trivial problems, since the pitch of the rotors blades has to be controlled while the whole rotor disk is tilted relative to its axis.

The device that makes this possible is the swashplate, and its engineering is not for the faint of heart. And yet [MonkeyMonkeey] chose not only to build a swashplate from scratch for a high school project, but since the parts were to be cast from aluminum, he had to teach himself the art of metal casting from the ground up. That includes building at least three separate furnaces, one of which was an electric arc furnace based on an arc welder with carbon fiber rods for electrodes (spoiler alert: bad choice). The learning curves were plentiful and steep, including getting the right sand mix for mold making and metallurgy by trial and error.

With some machining help from his school, [MonkeyMonkeey] finally came up with a good design, and we can’t wait to see what the rest of the ‘copter looks like. As he gets there, we’d say he might want to take a look at this series of videos explaining the physics of helicopter flight, but we suspect he’s well-informed on that topic already.

[via r/DIY]

Simple Quadcopter Testbed Clears The Air For Easy Algorithm Development

June 28, 2018 by Ben James 1 Comment

We don’t have to tell you that drones are all the rage. But while new commercial models are being released all the time, and new parts get released for the makers, the basic technology used in the hardware hasn’t changed in the last few years. Sure, we’ve added more sensors, increased computing power, and improved the efficiency, but the key developments come in the software: you only have to look at the latest models on the market, or the frequency of Git commits to Betaflight, Butterflight, Cleanflight, etc.

With this in mind, for a Hackaday prize entry [int-smart] is working on a quadcopter testbed for developing algorithms, specifically localization and mapping. The aim of the project is to eventually make it as easy as possible to get off the ground and start writing code, as well as to integrate mapping algorithms with Ardupilot through ROS.

The initial idea was to use a Beaglebone Blue and some cheap hobby hardware which is fairly standard for a drone of this size: 1250 kv motors and SimonK ESCs, mounted on an f450 flame wheel style frame. However, it looks like an off-the-shelf solution might be even simpler if it can be made to work with ROS. A Scanse Sweep LIDAR sensor provides point cloud data, which is then munched with some Iterative Closest Point (ICP) processing. If you like math then it’s definitely worth reading the project logs, as some of the algorithms are explained there.

It might be fun to add FPV to this system to see how the mapping algorithms are performing from the perspective of the drone. And just because it’s awesome. FPV is also a fertile area for hacking: we particularly love this FPV tracker which rotates itself to get the best signal, and this 3D FPV setup using two cameras.

Fail Of The Week: Two Rotors Are Not Better Than Four

June 12, 2018 by Dan Maloney 20 Comments

Fair warning: [Paweł Spychalski]’s video is mostly him talking about how bad his “dualcopter” ended up. There are a few sequences of the ill-fated UAV undergoing flight tests, most of which seem to end with it doing a reasonable impression of a post-hole auger. We have to admit that it’s a pretty poor drone. But one can only truly fail if one fails to have some fun doing it, [Paweł] enjoyed considerable success, at least judging by the glee with which he repeatedly cratered the craft.

The overall idea seems to make sense, with coaxial props mounted in the middle of a circular 3D-printed frame. Mounted below the props are crossed vanes controlled by two servos. The vanes sit in the rotor wash and provide pitch and roll control, while yaw and thrust are controlled by varying the speeds of the counter-rotating props. [Paweł] knew going in that this was a sketchy aerodynamic design, and was surprised it performed as well as it did. But with ground effects limiting roll and pitch control close to the ground, the less-than-adequate thrust due to turbulence between the rotors, and the tendency for the center of mass and the center of gravity to get out whack with each other, all made for a joyously unstable and difficult to control aircraft.

Despite the poor performance, [Paweł] has plans for a Mark II dualrotor, a smaller craft with some changes based on what he learned. He’s no slouch at pushing the limits with multirotors, with 3D-printed racing quad frames and using LoRa for control beyond visual range. Still, we’re sure he’d appreciate constructive criticism in the comments, and we wish him luck with the next one.

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Laser-Powered Flying Machine Weighs Milligrams

May 30, 2018 by Jenny List 21 Comments

We’ve become used to seeing some beautiful hand-made creations at the smaller end of the flying machine scale, tiny aircraft both fixed and rotary wing. An aircraft that weighs a few grams is entirely possible to build, such have been the incredible advances in component availability.

But how much smaller can a working aircraft be made? Given a suitable team and budget, how about into the milligrams? [Dr. Sawyer Fuller] and his team at the University of Washington have made an ornithopter which may be the lightest aircraft yet made, using a piezoelectric drive to flap flexible wings. That in itself isn’t entirely new, but whereas previous efforts had relied on a tether wire supplying electricity, the latest creation flies autonomously with its power supplied by laser to an on-board miniature solar cell that protrudes above the craft on its wires.

Frustratingly Dr. Fuller’s page on the machine is lighter on detail than we’d like, probably because they are saving the juicy stuff for a big reveal at a conference presentation. It is however an extremely interesting development from a technical perspective, as well as opening up an entirely new front in the applications for flying machines. Whatever happens, we’ll keep you posted.

You can see the craft in the video below the break, and if you’re interested lies with more conventional tiny machines take a look at the creator of a 2.9g Mustang model.

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Autonomous Spaceplane Travels To 10 Km, Lands Safely 200 Km Away

May 30, 2018 by Dan Maloney 39 Comments

Space balloons, where one sends instrument packages to the edge of space on a weather balloon, are a low-cost way to scratch the space itch. But once you’ve logged the pressure and temperature and tracked your balloon, what’s the next challenge? How about releasing an autonomous glider and having it return itself to Earth safely?

That’s what [IzzyBrand] and his cohorts did, and we have to say we’re mightily impressed. The glider itself looks like nothing to write home about: in true Flite Test fashion, it’s just a flying wing made with foam core and Coroplast reinforced with duct tape. A pair of servo-controlled elevons lies on the trailing edge of the wings, while inside the fuselage are a Raspberry Pi and a Pixhawk flight controller along with a GPS receiver. Cameras point fore and aft, a pair of 5200 mAh batteries provide the juice, and handwarmers stuffed into the avionics bay prevent freezing.

After a long series of test releases from a quadcopter, flight day finally came. Winds aloft prevented a full 30-kilometer release, so the glider was set free at 10 kilometers. The glider then proceeded to a pre-programmed landing zone over 80 kilometers from the release point. At one point the winds were literally pushing the glider backward, but the little plane prevailed and eventually spiraled down to a perfect landing.

We’ve been covering space balloons for a while, but take a moment to consider the accomplishment presented here. On a shoestring budget, a team of amateurs hit a target the size of two soccer fields with an autonomous aircraft from a range of almost 200 kilometers. That’s why we’re impressed, and we can’t wait to see what they can do after a release from the edge of space.

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“Watch Dogs” Inspired Hacking Drone Takes Flight

May 27, 2018 by Tom Nardi 19 Comments

They say that life imitates art, which in modern parlance basically means if you see something cool in a video game, movie or TV show, you might be inclined to try and build your own version. Naturally, such things generally come in the form of simple props, perhaps with the occasional embedded LED or noise making circuit. It’s not as if you can really build a phaser from Star Trek or a phone booth that’s bigger on the inside.

But after seeing the hacking quadcopter featured in the video game Watch Dogs 2, [Glytch] was inspired to start work on a real-world version. It doesn’t look much like the drone from the game, but that was never the point. The idea was to see how practical a small flying penetration testing platform is with current technology, and judging by the final build, we’d say he got his answer.

All the flight electronics are off the shelf quadcopter gear. It’s running on a Betaflight OMNIBUS F4 Pro V2 Flight controller with an M8N GPS mounted in the front and controlling the 2006 2400KV motors with a DYS F20A ESC. Interestingly [Glytch] is experimenting with using LG HG2 lithium-ion cells to power the quad rather than the more traditional lithium-polymer pack, though he does mention there are some issues with the voltage curve between the two battery technologies.

But the real star of the show is the payload: a Hak5 Pineapple Nano. As the Pineapple provides a turn-key penetration testing platform on its own, [Glytch] just needed a way to safely carry it and keep it powered. The custom frame keeps it snug, and the 5 Volt Battery Eliminator Circuit (BEC) on the DYS F20A ESC combined with a female USB port allows powering the Pineapple without having to make any hardware modifications.

We’ve seen quadcopters with digital weaponry before, though not nearly as many as you might think. But as even the toy grade quadcopters become increasingly capable, we imagine the airborne hacking revolution isn’t far away.

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