Building A Truss-Braced Model Airplane: Sense Or Nonsense?

Following NASA’s recent results with truss-braced wing airplanes and the benefits this could bring to full-sized airplanes, [Think Flight] figured that if it helps with those airplanes, perhaps it may also be a boon for model airplanes. With the recent construction of a carrier airplane for smaller drones, he decided to give the concept a whirl to see whether it would make a difference compared to a regular wing design. This carrier airplane features a payload bay that can be opened in flight to release the drones stored inside it, making any potential increased payload capacity and improvements to the flight characteristics very welcome.

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Building A Giant Remote Controlled Model Airbus A380 In A Year

A year ago [Ramy RC] set out on a momentous challenge: to build a 1:21 scale Airbus A380-800 RC model with functional engines, landing gear and all other details. Recently he finished the project and published a video with a summary of the whole build process (also linked below). The full video series can be found on the Ramy RC channel. The final RC airplane came out at a massive wingspan of 3.9 meters (12.7′), a length of 3.6 meters (11.8′) and a weight of 25 kg. This weight is carried by the full landing gear of multiple bogeys that can retract much like on the real airplane.

A range of materials were used for the body, including carbon fiber and wood, with each part carefully modeled with CAD software and 3D-printed or cut on a CNC cutter. Four ducted fans provide the propulsive power that lift this enormous model airplane into the skies, which is the only part where the noise profile doesn’t quite match that of the real A380. Even so, seeing the airplane taxing, taking off and flying through the skies makes you look twice to realize that it is in fact a scale model and not a real Emirates A380-800, also courtesy of the excruciating amount of detail to the model’s final look, down from the logos to the silver-grey lines.

We’re also quite convinced that the maiden flight of such an exquisite model has to be one of the most terrifying experiences imaginable.

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Flight Of The Pterothopter: A Jurassic-Inspired Ornithopter

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.

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Diaphragm Air Engine

One of the tricky parts of engineering in the physical world is making machines work with the available resources and manufacturing technologies. [Tom Stanton] has designed and made a couple of air-powered 3D printed engines but always struggled with the problem of air leaking past the 3D-printed pistons. Instead of trying to make an air-tight piston, he added a rubber membrane and a clever valve system to create a diaphragm air engine.

This GIF is worth 115 words

A round rubber diaphragm with a hole in the center creates a seal with the piston at the top of its stroke. A brass sleeve and pin protrude through the diaphragm, and the sleeve seals create a plug with an o-ring, while the pin pushes open a ball which acts as the inlet valve to pressurize an intermediate chamber. As the piston retracts, the ball closes the inlet valve, the outlet valve of the intermediate chamber is opened, forcing the diaphragm to push against the piston. The seal between the piston and diaphragm holds until the piston reaches its bottom position, where the pressurized air is vented past the piston and out through the gearbox. For full details see the video after the break.

It took a few iterations to get the engine to run. The volume of the intermediate chamber had to increase and [Tom] had to try a few different combinations of the sleeve and pin lengths to get the inlet timing right. Since he wanted to use the motor on a plane, he compared the thrust of the latest design with that of the previous version. The latest design improved efficiency by 366%. We look forward to seeing it fly! Continue reading “Diaphragm Air Engine”

This Hurricane Uses A Novel Technique

You’ve probably heard of the brave pilots, the so-called ‘few’, that took to the air in their Supermarine Spitfires and saved the day during the Battle of Britain. It’s a story that contains a lot of truth, but as is so often the case, it masks a story with a bit more complexity. Those pilots did scramble across the airfields of Southern England back in the summer of 1940, but more of them went into battle behind the controls of a Hawker Hurricane than its more glamorous stablemate.

The Hurricane might have been eclipsed by the Spitfire in the public’s eye, but not for [Marius Taciuc], who’s made a fully-functional RC model of one. Normally that wouldn’t be worthy of our attention, but in this case he’s employed a rather fascinating construction technique. He’s recreated the doped-fabric skin of the original by 3D-printing the frame of the aircraft and covering it in heat-shrink film, making this a very rare bird indeed.

The video below takes us through the steps including the development of the frame in a CAD package based on a tracing of a 2D aircraft picture, fitting the film, and finally attempts at flight that are unfortunately foiled by inappropriate wheel choice. But the short flight and crash does demonstrate that this construction method is durable, which leads on to our interest in it. While it evidently makes a functional aircraft, there are other applications that could benefit from such a lightweight and strong combination of materials.

[Marius] actually created a model of the somewhat more photogenic Spitfire using a similar technique, though as far as we can tell, that one has remained grounded. Incidentally, these pages have been previously graced by Hurricanes of the non-PLA variety. Continue reading “This Hurricane Uses A Novel Technique”

Your Drone Is Cool, But It’s No Jet Fighter

There are some communities with whom our happy band of hardware hackers share a lot in common, but with whom we don’t often associate. The more workshop-orientated end of the car modification or railway modeler scenes, for instance, or the model aircraft fraternity. Many of these communities exist more for the activity than for the making, some of them dabble with building kits, but among them are a hard core of people who create amazing projects from scratch.

Take [Igor Negoda], for example. Not content with building just any model aircraft, he’s built his own from scratch, to his own design. And if designing for yourself what amounts to a scaled-down jet fighter wasn’t enough, he’s also built his own jet engine to power it. His videos are all in Russian so use YouTube’s subtitle feature if you’re not a Russian speaker, but they’re so good that if you couldn’t access the English translation you’d want to learn the language just to hear his commentary.

The video below the break shows us first a fast-taxi test using a ducted fan, then a full test flight with the jet engine. There is an explanation of the fuel system and the flight control systems, before an impressive flight from what appears to be a former Cold War-era runway. There are a few funny moments such as transporting a large model jet aircraft in a small hatchback car, but the quality of the work in a garage workshop shines through. Suddenly a multirotor doesn’t cut it any more, we want a jet aircraft like [Igor]’s!

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Here’s The Reason The FAA’s Drone Registration System Doesn’t Make Sense

Last week, the US Department of Transportation and FAA released their rules governing drones, model aircraft, unmanned aerial systems, and quadcopters – a rose by any other name will be regulated as such. Now that the online registration system is up and running.

The requirements for registering yourself under the FAA’s UAS registration system are simple: if you fly a model aircraft, drone, control line model, or unmanned aerial system weighing more than 250g (0.55 lb), you are compelled under threat of civil and criminal penalties to register.

This is, by far, one of the simplest rules ever promulgated by the FAA, and looking at the full text shows how complicated this rule could have been. Representatives from the Academy of Model Aircraft, the Air Line Pilots Association, the Consumer Electronics Association weighed in on what types of aircraft should be registered, how they should be registered, and even how registration should be displayed.

Considerable attention was given to the weight limit; bird strikes are an issue in aviation, and unlike drones, bird strikes have actually brought down airliners. The FAA’s own wildlife strike report says, “species with body masses < 1 kilogram (2.2 lbs) are excluded from database,”. The Academy of Model Aircraft pushed to have the minimum weight requiring registration at two pounds, citing their Park Flyer program to define what a ‘toy’ is.

Rules considering the payload carrying ability of an unmanned aerial system were considered, the inherent difference between fixed wing and rotors or quadcopters was considered, and even the ability to drop toy bombs was used in the decision-making process that would eventually put all remotely piloted craft weighing over 250g under the FAA’s jurisdiction. We must at least give the FAA credit for doing what they said they would do: regulate drones in a way that anyone standing in line at a toy store could understand. While the FAA may have crafted one of the simplest rules in the history of the administration, this rule might not actually be legal.

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