The Coanda effect is an aerodynamic principle regarding the way fluids tend to flow along curved surfaces. This can be used to direct a flow, and [Tom Stanton] wanted to try out its application on a quadcopter. (Video embedded below.)
The project began by firing up the 3D printer, which made experimenting with a variety of different aerodynamic forms easy. Wishing to avoid simply putting a large obstruction in the way of an otherwise efficient propeller, the experiment first used impellers to direct flow sideways, over the edge of the Coanda domes. The impellers, combined with the Coanda domes, were a factor of 5 less efficient at generating thrust compared to a standard prop setup, but [Tom] persevered.
In testing, the drone was unable to fly outside of ground effect, with its weight exceeding its maximum thrust. However, [Tom] noted that the Coanda domes helped create a cushion of air when flying in this ground effect region that was far more than experienced with a typical prop drone.
Wanting some further success, [Tom] then replaced the impellers with standard drone props. This greatly improved performance, with the drone now able to fly out of ground effect and use far less power. However, its performance was still worse than a standard drone without Coanda domes fitted. [Tom] suspects that this is due to the weight penalty most of all.
While it’s unlikely you’ll see Coanda effect drones going mainstream anytime soon, [Tom]’s project goes to show that you can perform viable aerodynamic research at home with little more than a 3D printer and a fog machine. There’s plenty more fun you can have with the Coanda effect, too. Video after the break.
Continue reading “Putting The Coanda Effect To Work On A Quadcopter”
We spend a lot of time here at Hackaday talking about drone incidents and today we’re looking into the hazard of operating in areas where people are present. Accidents happen, and a whether it’s a catastrophic failure or just a dead battery pack, the chance of a multi-rotor aircraft crashing down onto people below is a real and persistent hazard. For amateur fliers, operating over crowds of people is simply banned, but there are cases where professionally-piloted dones are flying near crowds of people and other safety measures need to be considered.
We saw a skier narrowly missed by a falling camera drone in 2015, and a couple weeks back there was news of a postal drone trial in Switzerland being halted after a parachute system failed. When a multirotor somehow fails while in flight it represents a multi-kilogram
flying weapon widow-maker equipped with spinning blades, how does it make it to the ground in as safe a manner as possible? Does it fall in uncontrolled flight, or does it activate a failsafe technology and retain some form of control as it descends?
Continue reading “Safety Systems For Stopping An Uncontrolled Drone Crash”
After the alleged drone attacks on London Gatwick airport in 2018 we’ve been on the look out for effective countermeasures against these rogue drone operators. An interesting solution has been created by [Ogün Levent] in Turkey and is briefly documented on in his Dronesense page on Crowdsupply. There’s a few gaps in the write up due to non-disclosure agreements, but we might well be able to make some good guesses as to the missing content.
Not one, but two LimeSDRs are sent off into the air onboard a custom made drone to track down other drones and knock them out by jamming their signals, which is generally much safer than trying to fire air to air guided missiles at them!
The drone hardware used by [Ogün Levent] and his team is a custom-made S600 frame with T-Motor U3 motors and a 40 A speed controller, with a takeoff weight of 5 kg. An Adventech single board computer is the master controller with a Pixhawk secondary and, most importantly, a honking great big 4 W, 2.4 GHz frequency jammer with a range of 1200 meters.
The big advantage of sending out a hunter drone with countermeasures rather than trying to do it on the ground is that, being closer to the drone, the power of the jammer can be reduced, thus creating less disturbance to other RF devices in the area – the rogue drone is specifically targeted.
One of the LimeSDRs runs a GNU radio flowgraph with a specially designed block for detecting the rogue drone’s frequency modulation signature with what seems to be a machine learning classification script. The other LimeSDR runs another *secret* flowgraph and a custom script running on the SBC combines the two flowgraphs together.
So now it’s the fun part, what does the second LimeSDR do? Some of the more obvious problems with the overall concept is that the drone will jam itself and the rogue drone might already have anti-jamming capabilities installed, in which case it will just return to home. Maybe the second SDR is there to track the drone as it returns home and thereby catch the human operator? Answers/suggestions in the comments below! Video after the break. Continue reading “Drone On Drone Warfare, With Jammers”
Lithium batteries and brushless motors helped make multirotor drones possible, but batteries only last so long. Liquid fuels have far greater energy densities, but have not been widely applied in these roles. [Tech Ingredients] has been experimenting with a compact gasoline-fueled generator, with the aim to extend drone flight times well beyond what is currently possible with batteries (Youtube link, embedded below).
The build began with a single-cylinder, four stroke engine. However, torque spikes and vibration made things difficult. After some iteration, the design settled on employing two single-cylinder two stroke engines, fitted with a timing belt to keep them 180 degrees out of phase. In combination with a pair of balanced flywheels, this keeps vibration to a minimum. Brushless motors are used as generators, combined with rectifier diodes and capacitors to smooth the voltage output. The generator is intended to be used in parallel with a lithium battery pack in order to ensure the drone always has power available, even in the event of a temporary malfunction.
This is a build with plenty of promise, and we can’t wait to see what kind of flight time can be achieved once the system is finished and flight ready. We’ve seen others experimenting with hybrid drones, too.
Continue reading “Designing Compact Gasoline Generator Prototype For Drone Use”
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.
Continue reading “Hybrid Drones Could Have Massively Extended Flight Times”
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.
Continue reading “Hoverboard Circles Bastille Day”
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!