Hybrid Drones Could Have Massively Extended Flight Times

July 19, 2019 by Lewin Day 130 Comments

Multirotor drones truly took off with the availability of lithium polymer batteries, brushless motors, and cheap IMUs. Their performance continues to improve, but their flight time remains relatively short due to the limits of battery technology. [Nicolai Valenti] aims to solve the problem by developing a hybrid generator for drones.

The basic concept consists of a small gasoline engine, connected to a brushless motor employed as a generator. The electricity generated is used to run the main flight motors of the multirotor drone. The high energy density of gasoline helps to offset the added weight of the generator set, and [Nicolai] is aiming to reach a goal of two hours of flight time.

There are many engineering problems to overcome. Engine starting, vibration and rectification are all significant challenges, but [Nicolai] is tackling them and has already commenced flight testing. Experiments are ongoing with 500 W, 1,000 W, and 2,000 W designs, and work is ongoing to optimise the engine and electronics package.

It’s a project that holds the potential to massively expand the range of operation for medium to large multirotors, and should unlock certain capabilities that have thus far been limited by short battery runtimes. Gasoline powered drones aren’t a new idea, but we’ve seen precious little in the hybrid space. We look forward to seeiing how this technology develops. Video after the break.

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Hoverboard Circles Bastille Day

July 15, 2019 by Al Williams 36 Comments

According to reports, a turbine-powered flying board buzzed around Bastille Day celebrations carrying its inventor [Franky Zapata] toting a rifle to promote the military applications of the Flyboard Air. You can see the video record, below.

We’ve heard the board costs a cool $250,000 so you may want to start saving now. There are several versions including one that qualifies in the United States as an ultralight. The board Zapata used can reach speeds of 190 km/h and can run for up to 10 minutes, although the website claims 200 km/h is possible and the company also claims to routinely reach 140 km/h. and 6 minute flight times.

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DJI Fights Back Over Sensationalist Drone Reporting

July 7, 2019 by Jenny List 69 Comments

Over the past few years the number of reported near misses between multirotors, or drones as they are popularly referred to, and aircraft has been on the rise. While evidence to back up these reports has been absent time and again.

We’ve looked at incident reports, airport closures, and media reporting. The latest chapter comes in the form of a BBC documentary, “Britain’s Next Air Disaster? Drones” whose angle proved too sensational and one-sided for the drone manufacturing giant DJI. They have penned an acerbic open letter to the broadcaster (PDF link to the letter itself) that says that they will be launching an official complaint over the programme’s content. The letter begins with the following stinging critique:

As the world’s leader in civilian drones and aerial imaging technology, we feel it is our duty on behalf of the millions of responsible drone users around the globe, to express our deep disappointment at the BBC’s negative portrayal of drone technology and one-sided reporting based on hearsay.

It then goes on to attack the tone adopted by the presenter in more detail : “overwhelmingly negative, with the presenter frequently using the words ‘catastrophic’ and ‘terrifying’.“, before attacking the validity of a series of featured impact tests and highlighting the questionable basis for air proximity incident reports. They round the document off with a run through the safety features that they and other manufacturers are incorporating into their products.

DJI have pulled no punches in their condemnation of the standard of reporting on drone incidents in this document, and it is a welcome and rare sight in an arena in which the voices of people who know something of multirotors have been rather lonely and ignored. The BBC in turn have responded by saying “its investigation had shown positive uses of drones and that its programmes were fair“.

Over the past few years we have reported on this issue we have continually made the plea for a higher quality of reporting on drone stories. While Britain has been the center of reporting that skews negatively on the hobby, the topic is relevant wherever in the world there are nervous airspace regulators with an eye to any perceived menace. These incidents have pushed the industry to develop additional safety standards, as DJI mentions in their letter: “the drone industry itself has implemented various features to mitigate the risks described”. Let’s hope this first glimmer of a fight-back from an industry heavyweight (with more clout than the multirotor community) will bear the fruit of increased awareness from media, officials, and the general public.

If you’d like to see the BBC documentary in question it will be available for the next few weeks to people who see the Internet through a British IP address.

Thanks [Stuart] for the tip!

Build Your Own Selfie Drone With Computer Vision

June 30, 2019 by Brian Benchoff 10 Comments

In late 2013 and early 2014, in the heady days of the drone revolution, there was one killer app — the selfie drone. Selfie sticks themselves had already become a joke, but a selfie drone injected a breath of fresh air into the world of tech. Fidget spinners had yet to be invented, so this is really all we had. It wasn’t quite time for the age of the selfie drone, though, and the Lily camera drone — in spite of $40 Million in preorders — became the subject of lawsuits, and not fines from the FAA.

Technology marches ever forward, and now you can build your own selfie drone. That’s exactly what [geaxgx] did, although this build uses a an off-the-shelf drone with custom software instead of building everything from scratch.

For hardware, this is a Ryze Tello, a small, $100 quadcopter with a front-facing camera. With the right libraries, you can stream images to a computer and send flight commands back to the drone. Yes, all the processing for the selfie drone happens on a non-flying computer, because computer vision takes processing power and battery life.

The software comes from CMU’s OpenPose library, a real-time solution for detecting a body, face, or hands. With this, [geaxgx] was able to hover the drone and keep his face in the middle of the camera’s frame. While there’s no movement of the drone involved — the drone is just hovering and rotating to the left and right — it is a flying selfie stick without the stick. You can check out the video below and check out all the code on [geaxgx]’s GitHub here.

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Thrust Vectoring With Compliant Mechanisms Is Hard

June 16, 2019 by Lewin Day 19 Comments

Thrust vectoring is one way to control aerial vehicles. It’s become more popular as technology advances, finding applications on fifth-generation fighter aircraft, as well as long being used in space programmes the world over.[RCLifeOn] decided to try and bring the technology to a prop-powered RC aircraft, in an unconventional way.

After attending a lecture on compliant mechanisms and their potential use in space vehicles for thrust vectoring control, [RCLifeOn] decided to try applying the concept himself. His test mechanism is a fixed-wing with a single-piece motor mount that has enough flex in the right places to allow the motor (and propeller) to be moved in two axes, achieving thrust vectoring control.

After printing a compliant motor mount in a variety of materials, one was selected for having the right balance of strength and flexibility. The vectoring mechanism was fitted to a basic flying wing RC aircraft, and taken to the field for testing. Unfortunately, success was not the order of the day. While the mechanism was able to flex successfully and vector the motor in bench testing, it was unable to hold up to the stresses of powered flight. The compliant mechanism failed and the plane nosedived to the ground.

[RCLifeOn] suspects that the basic concept is a difficult proposition to engineer properly, as adding strength would tend to add weight which would make flight more difficult. Regardless, we’d love to see further development of the idea. It’s not the first time we’ve seen his 3D-printed flight experiments, either. Video after the break.

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Unconventional Drone Uses Gas Thrusters For Control

June 8, 2019 by Dan Maloney 28 Comments

You’ve got to hand it to [Tom Stanton] – he really thinks outside the box. And potentially outside the atmosphere, to wit: we present his reaction control gas thruster-controlled drone.

Before anyone gets too excited, [Tom] isn’t building drones for use in a vacuum, although we can certainly see a use case for such devices. This is more of a hybrid affair, with counter-rotating props mounted in a centrally located duct providing the lift and the yaw control. Flanking that is a triangular frame supporting three two-liter soda bottle air reservoirs, each of which supplies a down-firing nozzle at each apex of the triangle. Solenoid valves control the flow of compressed air from the bottles to the nozzles, providing thrust to stabilize the roll and pitch axes. As there aren’t many off-the-shelf flight control systems set up for reaction control, [Tom] had to improvise thruster control; an Arduino watches the throttle signals normally sent to a drone’s motors and fires the solenoids when they get to a preset threshold. It took some tuning, but [Tom] was eventually able to get a stable, untethered hover. And he’s right – the RCS jets do sound amazing when they’re firing, as long as the main motors are off.

This looks as though it has a lot of potential, and we’d love to see it developed more. It reminds us a bit of this ducted-prop drone, another great example of stretching conventional drone control concepts to the limit.

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Designing A Drone To Fire From A Grenade Launcher

June 6, 2019 by Tom Nardi 56 Comments

You might think that tiny autonomous drones that can be fired out of a standard 40 mm grenade launcher for rapid deployment would be the kind of thing the military would love to get their hands on. Which is true, of course, and a number of companies are working on the idea for police and military applications. But [Glytch] thinks the technology could also be used for search and rescue operations, so he’s working on creating a version for us civilians.

During his presentation “3D Printing Canister-Launchable Drones for City-Scale Wardriving” at the 2019 CircleCityCon, [Glytch] gave an overview of his progress towards creating a small fixed-wing Unmanned Aerial Vehicle (UAV) that can be built even by those of us who don’t have the budgets of a three letter government agency. He’s not at the point where he can do a test launch just yet, but the design is coming along nicely, and we’re extremely interested in seeing where it goes from here.

The only way you’re fitting a winged aircraft into the bore of a 40 mm launcher is by folding it up, and so far, that’s where [Glytch] has directed most of his efforts. The wings of his UAV will use a rigid leading edge that folds flat until deployment. When in flight mode, ripstop nylon attached between the body of the drone and the leading edge will be pulled taught to form the actual wing surface; think of it sort of like a bat’s wing. A similar trick will be used for the two control surfaces at the rear of the craft.

Internally, the UAV is using all off-the-shelf components which [Glytch] hopes will keep it cheap enough that they could eventually be mass produced. As he explained in a recent YouTube video, the motor, speed controller, receiver, and flight controller, are all the sort of thing you’d expect to find in a small RC quadcopter. To make it easier to manage the UAV in the field, the batteries and payload will be housed in a detachable nose cone; allowing the user to rapidly configure the hardware for different missions.

Right now, [Glytch] says the biggest obstacle keeping his drone out of the air is finding a foldable propeller with the specific characteristics he requires. Unable to find anything commercially available, he’s currently looking into designing it himself and having it 3D printed on an SLA machine. He also needs to design a sabot to hold the drone as it travels through the barrel of the launcher. Incidentally, he’s currently testing his design with an Airsoft grenade launcher, as he doesn’t want to wade through the paperwork involved in getting the real deal.

[Glytch] is no stranger to the world of high-tech UAVs. The “Watch Dog” inspired hacking drone he created last year was a huge hit, and he’s recently been working on a HD video and telemetry link over WiFi with the Raspberry Pi Zero for his flying creations.

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