Thrust Vectoring With Compliant Mechanisms Is Hard

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

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

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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The UK Drone Community Fights Back, Gains FOI Admission Of No Tangible Drone Evidence

Regular Hackaday readers will have noted a succession of stories following the reports of drones in the air over British airports and in proximity to aircraft. We’ve consistently asked for a better quality of investigation and reporting into these cases, because so far the absence of reported tangible evidence of a drone being present casts doubt on the validity of the official reaction. For too long the official records of air proximity incidents have relied upon a shockingly low standard of proof when apportioning blame to drone operators, and this situation has contributed to something of a panic over the issue.

It seems that some members of the British drone flying community are on the case though. Airprox Reality Check are a group analysing air proximity reports and linking them to contemporary ADS-B and weather records to identify possible explanations. They have devised a rating system based upon a number of different metrics in an attempt to quantify the reliability of a particular report, and they are tabulating their analysis of air proximity reports on a month by month basis. This includes among many analyses such gems as Airprox Report #2019046, in which an Embraer 170 flying at 9000 feet and 20 km offshore reported a drone in close proximity. The Airprox Reality Check analysis points out that no known drone could manage that feat, and refers to a passing Boeing 737 revealed through ADS-B data as a more likely culprit.

Their latest news is that they have made a Freedom of Information request to the Air Proximity Board, asking for what evidence the Board has of a drone having been involved in any of the over 350 incidents in UK airspace having been reported as involving drones. The official response contains the following quote:

in all cases UKAB has no confirmation that a drone has flown close to an aircraft other than the report made by the pilot(s). Similarly, other than from the report of the pilot(s), UKAB has no confirmation that a drone was involved.

This confirms the view of the multirotor and drone community that has been reported by Hackaday in the past, that the whole British drone panic has been based upon unreliable and uncorroborated reports from eyewitnesses with little direct experience of multirotors. If any irresponsible drone operator is flying into close proximity with aircraft or otherwise into protected airspace then it goes without saying that they should be prosecuted, yet it seems that the community is being punished as though this had happened when the reality is that no such acts are proven to have occurred.

A Hydrogen Fuel Cell Drone

When we think about hydrogen and flying machines, it’s quite common to imagine Zeppelins, weather balloons and similar uses of hydrogen in lighter-than-air craft to lift stuff of the ground. But with smaller and more efficient fuel cells, hydrogen is gaining its place in the drone field. Project RACHEL is a hydrogen powered drone project that involves multiple companies and has now surpassed the 60 minutes of flight milestone.

The initial target of the project was to achieve 60 minutes of continuous flight while carrying a 5 kg payload. The Lithium Polymer battery-powered UAVs flown by BATCAM allow around 12 minutes of useable flight. The recent test of the purpose-built fuel cell powered UAV saw it fly for an uninterrupted 70 minutes carrying a 5 kg payload.  This was achieved on a UAV with below 20 kg maximum take-off mass, using a 6-litre cylinder containing hydrogen gas compressed to 300 bar.

While this is not world record for drones and it’s not exactly clear if there will be a commercial product nor the price tag, it is still an impressive feat for a fuel cell powered flying device. You can watch the footage of one of their tests bellow:

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Drone Registration Tax Sought By UK’s CAA

As the UK’s aviation regulator, the Civil Aviation Authority is tasked with “making aviation better for those who choose to fly and those who do not”. Their latest plan to further this mission comes in the form of a drone registration tax. The proposal, which is open to online responses until 7 June, seeks to pass on the cost of a drone registration system to those who register themselves.

Proposals for a drone registration scheme have been in the works for a while now, and if enacted it would go into effect on 1 November. Owners of craft weighing more than 250 g (0.55 lbs) would have to fork out £16.50 ($21.50) per year, ostensibly to pay for the administration of the scheme. The CAA are basing this rate on as many as 170,000 people registering. In the US, the FAA has a drone registration program in place that requires registration based on the same 250 g weight guideline, but only charges $5 (£3.82) for a 3-year license, about thirteen times less than the CAA proposal.

Long-time readers will be familiar with our ongoing coverage of the sometimes-farcical saga of drone sightings in British skies. Airports have been closed (and implausible excuses have been concocted), but one thing remains constant: no tangible proof of any drone has yet been produced. Faced with a problem it doesn’t fully understand, the British Government is looking to this registration program.

It goes without saying that people misusing drones and endangering public safety should be brought to justice as swiftly as possible. But our concern is that the scale of the problem has been vastly over-represented, and that this scheme will do little to address either the problem of bogus drone sightings or the very real problem of criminal misuse of drones for example to smuggle contraband into prisons. It’s difficult to think this measure will have an effect on the number of incidents blamed on drones, and the high cost included in the proposal is a troubling burden for enthusiasts who operate responsibly.

Battlebots To The Skies!

If you’re too young to remember Battlebots on the television, there are two things that you should know. First is that there are plenty of highlights of this epic robot battle royale on YouTube, and the second is that now there’s an even better version with drones instead of robots merely confined to land. It’s called DroneClash 2019, and it looks like it was amazing.

Not only were the robots set up in a box and asked to battle each other, they first had to navigate down a corridor with anti-drone measures. The drones have to make it through and into a battle royale in the final room. If this wasn’t good enough, the event was opened by a prince of the Netherlands and is put on by a university.

This is an annual event to push the state of the art in drone and anti-drone tech, but we’d be happy to see it optioned for a TV show. If it doesn’t, you might be satisfied with a giant human-driven robot competition from a while back, or maybe just head down the rabbit hole of old Battlebots clips.

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