Electric RC Plane Flies For Almost 11 Hours

June 27, 2021 by Danie Conradie 45 Comments

Electric RC aircraft are not known for long flight times, with multirotors usually doing 20-45 minutes, while most fixed wings will struggle to get past two hours. [Matthew Heiskell] blew these numbers out of the water with a 10 hour 45 minute flight with an RC plane on battery power. Condensed video after the break.

Flight stats right before touchdown. Flight time in minutes on the left, and miles travelled second from the top on the right.

The secret? An efficient aircraft, a well tuned autopilot and a massive battery. [Matthew] built a custom 4S 50 Ah li-ion battery pack from LG 21700 cells, with a weight of 2.85 kg (6.3 lbs). The airframe is a Phoenix 2400 motor glider, with a 2.4 m wingspan, powered by a 600 Kv brushless motor turning a 12 x 12 propeller. The 30 A ESC’s low voltage cutoff was disabled to ensure every bit of juice from the battery was available.

To improve efficiency and eliminate the need to maintain manual control for the marathon flight, a GPS and Matek 405 Wing flight controller running ArduPilot was added. ArduPilot is far from plug and play, so [Matthew] would have had to spend a lot of timing tuning and testing parameters for maximum flight efficiency. We are really curious to see if it’s possible to push the flight time even further by improving aerodynamics around the protruding battery, adding a pitot tube sensor to hold the perfect airspeed speed on the lift-drag curve, and possibly making use of thermals with ArduPilot’s new soaring feature.

A few of you are probably thinking, “Solar panels!”, and so did Matthew. He has another set of wings covered in them that he used to do a seven-hour flight. While it should theoretically increase flight time, he found that there were a number of significant disadvantages. Besides the added weight, electrical complexity and weather dependence, the solar cells are difficult to integrate into the wings without reducing aerodynamic efficiency. Taking into account what we’ve already seen of [rcflightest]’s various experiments/struggles with solar planes, we are starting to wonder if it’s really worth the trouble. Continue reading “Electric RC Plane Flies For Almost 11 Hours” →

Helicopter Is Full Of Compressed Air

April 27, 2021 by Al Williams 14 Comments

[Tom] likes to build little helicopters and decided to build one that runs on compressed air. (Video, embedded below.) Turns out it was a little harder than he thought. Originally, he was trying for a compressed air quadcopter. He’d already worked with an air turbine, but putting on a vehicle that can lift itself into the air turns out to have a lot of hidden gotchas.

[Tom] went through a lot of design considerations to arrive at the helicopter design. He considered counter-rotating props, but there were a host of problems involved. He finally settled on a single prob with a tail rotor that resides on the far end of a long boom to allow the resulting lever arm to reduce the work required of the tail rotor.

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Taking Reverse Engineering To The Skies: Cheap Drone Gets PX4 Autopilot

April 24, 2021 by Stephen Ogier 3 Comments

Sometimes bad software is all that is holding good hardware back. [Michael Melchior] wanted to scavenge some motors and propellers for another project, so he bought an inexpensive quadcopter intending to use it for parts. [Michael] was so surprised at the quality of the hardware contained in his $100 drone that he decided to reverse engineer his quadcopter and give the autopilot firmware a serious upgrade.

Upon stripping the drone down, [Michael] found that it came with a flight management unit based on the STM32F405RG, an Inertial Measurement Unit, magnetic compass, barometric pressure sensor, GPS, WiFi radio, camera with tilt, optical flow sensor, and ultrasonic distance sensor, plus batteries and charger! The flight management unit also had unpopulated headers for SWD, and—although the manufacturer’s firmware was protected from reading—write protection hadn’t been enabled, so [Michael] was free to flash his own firmware.

We highly recommend you take a look at [Michael]’s 10 part tour de force of reverse engineering which includes a man-in-the-middle attack with a Raspberry Pi to work out its WiFi communication, porting the open-source autopilot PX4 to the new airframe, and deciphering unknown serial protocols. There are even amusing shenanigans like putting batteries in the oven and freezer to help figure out which registers are used as temperature sensors. He achieves liftoff at the end, and we can’t wait to see what else he’s able to make it do in the future.

Of course, [Michael] is no stranger to hacking imported quadcopters, and if you’re interested in PX4 but want something quieter than a quadcopter, take a look at this autopilot-equipped glider.

LED Hack Teaches DJI Mini 2 Drone New Tricks

April 20, 2021 by Tom Nardi 18 Comments

Despite its diminutive proportions, the thrust to weight ratio of the DJI Mini 2 is high enough that it can carry a considerable amount of baggage. So it’s no surprise that there’s a cottage industry of remotely controlled payload releases that can be bolted onto the bottom of this popular quadcopter. But [tterev3] wanted something that would integrate better with DJI’s software instead of relying on a separate transmitter.

As explained in the video below, his solution was to tap into the signals that control the RGB LED on the front of the drone. Since the user can change the color of the LED at any time with the official DJI smartphone application, decoding this signal to determine which color had been selected is like adding several new channels to the transmitter. In this case [tterev3] just needed to decode a single color to use as a “drop” signal, but it’s not hard to imagine how this concept could be expanded to trigger several different actions with a few more lines of code.

[tterev3] wrote some software to decode the 48 bits of data being sent to the LED with a PIC18F26K40 microcontroller, which in turn uses an L9110H H-Bridge to control a tiny gear motor. To get feedback, he’s using a small magnet glued to the release arm and a Hall-effect sensor.

Concerned about how much power he could realistically pull from a connection that was intended for an LED, he gave the release its own battery that is slowly charged while the drone is running. You could argue that since the motor only needs to fire up once to drop the payload, [tterev3] probably could have gotten away with not recharging it at all during the flight. But as with the ability to decode additional color signals, the techniques being demonstrated here hold a lot of promise for future development.

Folks have been strapping additional hardware to commercial quadcopters for years, but modifications like this one that actually let the craft release its payload and fly away hold particular promise for environmental monitoring and building mesh communication networks.

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The Wright Stuff: First Powered Flight On Mars Is A Success

April 19, 2021 by Dan Maloney 59 Comments

When you stop to think about the history of flight, it really is amazing that the first successful flight the Wright brothers made on a North Carolina beach to Neil Armstrong’s first steps on the Moon spanned a mere 66 years. That we were able to understand and apply the principles of aerodynamics well enough to advance from delicate wood and canvas structures to rockets powerful enough to escape from the gravity well that had trapped us for eons is a powerful testament to human ingenuity and the drive to explore.

Ingenuity has again won the day in the history of flight, this time literally as the namesake helicopter that tagged along on the Mars 2020 mission has successfully flown over the Red Planet. The flight lasted a mere 40 seconds, but proved that controlled, powered flight is possible on Mars, a planet with an atmosphere that’s as thin as the air is at 100,000 feet (30 km) above sea level on Earth. It’s an historic accomplishment, and the engineering behind it is worth a deeper look.

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Learn Multirotors From First Principles

April 11, 2021 by Jenny List 5 Comments

Multirotors, or drones as they’re popularly called, are so ubiquitous as to have become a $10 toy. They’re no less fun to fly for it though, and learning how they work is no less fascinating. It’s something [Science Buddies] has addressed in a series of videos examining them from first principles. They may be aimed at youngsters, but they’re still an entertaining enough watch for those of advancing years.

Instead of starting with a multirotor control board, the video takes four little DC motors and two popsicle sticks to make a rudimentary drone frame. Then with the help of dowels and springs it tethers the craft as the control mechanisms are explained bit by bit, from simple on-off motor control through proportional control to adding an Arduino and following through to how a multirotor stays in flight. It’s instructional and fun to watch, and maybe even for some of us, a chance to learn something.

We’ve had multirotor projects aplenty here over the years, but how about something completely different made from popsicle sticks?

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Flight Of The Pterothopter: A Jurassic-Inspired Ornithopter

April 6, 2021 by Zach Zeman 14 Comments

Ornithopters look silly. They look like something that shouldn’t work. An airplane with no propeller and wings that go flappy-flappy? No way that thing is going to fly. There are, however, a multitude of hobbyists, researchers, and birds who would heartily disagree with that sentiment, because ornithopters do fly. And they are almost mesmerizing to watch when they do it, which is just one reason we love [Hobi Cerdas]’s build of the Pterothopter, a rubber band-powered ornithopter modeled after a pterodactyl.

All joking aside, the science and research behind ornithopters and, relatedly, how living organisms fly is fascinating in itself — which is why [Lewin Day] wrote that article about how bees manage to become airborne. We can lose hours reading about this stuff and watching videos of prototypes. While most models we can currently build are not as efficient as their propeller-powered counterparts, the potential of evolutionarily-perfected flying mechanisms is endlessly intriguing. That alone is enough to fuel builds like this for years to come.

As you can see in the video below, [Hobi Cerdas] went through his own research and development process as he got his Pterothopter to soar. The model proved too nose-heavy in its maiden flight, but that’s nothing a little raising of the tail section and a quick field decapitation couldn’t resolve. After a more successful second flight, he swapped in a thinner rubber band and modified the wing’s leading edge for more thrust. This allowed the tiny balsa dinosaur to really take off, flying long enough to have some very close encounters with buildings and trees.

For those of you already itching to build your own Pterothopter, the plans come from the Summer 2017 issue of Flapping Wings, the official newsletter of the Ornithopter Society (an organization we’re so happy to learn about today). You can also find more in-depth ornithopter build logs to help you get started. And, honestly, there’s no reason to limit yourself to uncontrolled flight; we’ve come across some very impressive RC ornithopters in the past.

Continue reading “Flight Of The Pterothopter: A Jurassic-Inspired Ornithopter” →