Teardown: D50761 Aircraft Quick Access Recorder

Everyone’s heard of the “black box”. Officially known as the Flight Data Recorder (FDR), it’s a mandatory piece of equipment on commercial aircraft. The FDR is instrumental in investigating incidents or crashes, and is specifically designed to survive should the aircraft be destroyed. The search for the so-called “black box” often dominates the news cycle after the loss of a commercial aircraft; as finding it will almost certainly be necessary to determine the true cause of the accident. What you probably haven’t heard of is a Quick Access Recorder (QAR).

While it’s the best known, the FDR is not the only type of recording device used in aviation. The QAR could be thought of as the non-emergency alternative to the FDR. While retrieving data from the FDR usually means the worst has happened, the QAR is specifically designed to facilitate easy and regular access to flight data for research and maintenance purposes. Its data is stored on removable media and since the QAR is not expected to survive the loss of the aircraft it isn’t physically hardened. In fact, modern aircraft often use consumer-grade technology such as Compact Flash cards and USB flash drives as storage media in their QAR.

Through the wonders of eBay, I recently acquired a vintage Penny & Giles D50761 Quick Access Recorder. This was pulled out of an aircraft which had been in service with the now defunct airline, Air Toulouse International. Let’s crack open this relatively obscure piece of equipment and see just what goes into the hardware that airlines trust to help ensure their multi-million dollar aircraft are operating in peak condition.

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Studying Airplane Radio Reflections With SDR

A property of radio waves is that they tend to reflect off things. Metal surfaces in particular act as good reflectors, and by studying how these reflections work, it’s possible to achieve all manner of interesting feats. [destevez] decided to have some fun with reflections from local air traffic, and was kind enough to share the results.

The project centers around receiving 2.3 GHz signals from a local ham beacon that have been reflected by planes taking off from the Madrid-Barajas airport. The beacon was installed by a local ham, and transmits a CW idenfication and tone at 2 W of power.

In order to try and receive reflections from nearby aircraft, [destevez] put together a simple but ingenious setup.

ADS-B data was plotted on a map and correlated with the received reflections.

A LimeSDR radio was used, connected to a 9 dB planar 2.4 GHz WiFi antenna. This was an intentional choice, as it has a wide radiation pattern which is useful for receiving reflections from odd angles. A car was positioned between the antenna and the beacon to avoid the direct signal overpowering reflected signals from aircraft.

Data was recorded, and then compared with ADS-B data on aircraft position and velocity, allowing recorded reflections to be matched to the flight paths of individual flights after the fact. It’s a great example of smart radio sleuthing using SDR and how to process such data. If you’re thirsty for more, check out this project to receive Russian weather sat images with an SDR.

[Thanks to Adrian for the tip!]

Open Source Paramotor Using Quadcopter Tech

Have you ever dreamed of flying, but lack the funds to buy your own airplane, the time to learn, or the whole hangar and airstrip thing? The answer might be in a class of ultralight aircraft called powered paragliders, which consist of a soft inflatable wing and a motor on your back. As you may have guessed, the motor is known as a paramotor, and it’s probably one of the simplest powered aircraft in existence. Usually little more than big propeller, a handheld throttle, and a gas engine.

But not always. The OpenPPG project aims to create a low-cost paramotor with electronics and motors intended for heavyweight multicopters. It provides thrust comparable to gas paramotors for 20 to 40 minutes of flight time, all while being cheaper and easier to maintain. The whole project is open source, so if you don’t want to buy one of their kits or assembled versions, you’re free to use and remix the design into a personal aircraft of your own creation.

It’s still going to cost for a few thousand USD to get a complete paraglider going, but at least you won’t need to pay hangar fees. Thanks to the design which utilizes carbon fiber plates and some clever hinges, the whole thing folds up into a easier to transport and store shape than traditional paramotors with one large propeller. Plus it doesn’t hurt that it looks a lot cooler.

Not only are the motors and speed controls borrowed from the world of quadcopters, but so is the physical layout. A traditional paramotor suffers from a torque issue, as the big propeller wants to twist the motor (and the human daring enough to strap it to his or her back) in the opposite direction. This effect is compensated for in traditional gas-powered paramotor by doing things like mounting the motor at an angle to produce an offset thrust. But like a quadcopter the OpenPPG uses counter-rotating propellers which counteract each others thrust, removing the torque placed on the pilot and simplifying design of the paraglider as a whole.

If you still insist on the fixed-wing experience, you could always get some foam board and hope for the best.

[Thanks to Luke for the tip.]

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Building An Ultralight In A Basement is Just So Beautiful to See

[Peter] is at it again. Not content with being one of the best RC confabulators on YouTube, and certainly not content with the first airplane he built in his basement, [Peter Sripol] is building another airplane in his basement.

The first airplane he built was documented on YouTube over a month and a half. It was an all-electric biplane, built from insulation foam covered in fiberglass, and powered by a pair of ludicrously oversized motors usually meant for large-scale RC aircraft. This was built under Part 103 regulations — an ultralight — which means there were in effect no regulations. Anyone could climb inside one of these without a license and fly it. The plane flew, but there were a few problems. It was too fast, and the battery life wasn’t really what [Peter] wanted.

Now [Peter] is onto his next adventure. Compared to the previous plane, this has a more simplified, traditional construction. It’s a high wing monoplane with an aluminum frame. There are two motors again, although he’s still in the process of finding lower kV motors. This plane should also fly slower, longer, something you really want in an ultralight.

As far as tools required for this build, it’s surprising how few are needed to put the plane together. Of course, there are a few excessively large pop rivet guns and there will be some extra special aviation-grade bolts, but the majority of this plane will be made out of standard aluminum, insulation foam, a bit of wood, and some fiberglass. Watching [Peter] churn out high-end fabrication with these simple parts is so satisfying. If you have a drill press with a cross slide vise, you too can build a plane in your basement.

This is shaping up to be a truly fantastic build. [Peter] has already proven that yes, he can indeed build an airplane in his basement. This time, though, he’s going to have a plane that will stay in the air for more than just a few minutes.

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Laser-Powered Flying Machine Weighs Milligrams

We’ve become used to seeing some beautiful hand-made creations at the smaller end of the flying machine scale, tiny aircraft both fixed and rotary wing. An aircraft that weighs a few grams is entirely possible to build, such have been the incredible advances in component availability.

But how much smaller can a working aircraft be made? Given a suitable team and budget, how about into the milligrams? [Dr. Sawyer Fuller] and his team at the University of Washington have made an ornithopter which may be the lightest aircraft yet made, using a piezoelectric drive to flap flexible wings. That in itself isn’t entirely new, but whereas previous efforts had relied on a tether wire supplying electricity, the latest creation flies autonomously with its power supplied by laser to an on-board miniature solar cell that protrudes above the craft on its wires.

Frustratingly Dr. Fuller’s page on the machine is lighter on detail than we’d like, probably because they are saving the juicy stuff for a big reveal at a conference presentation. It is however an extremely interesting development from a technical perspective, as well as opening up an entirely new front in the applications for flying machines. Whatever happens, we’ll keep you posted.

You can see the craft in the video below the break, and if you’re interested lies with more conventional tiny machines take a look at the creator of a 2.9g Mustang model.

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Kapton: Miracle Material with a Tragic History

On a balmy September evening in 1998, Swissair flight 111 was in big trouble. A fire in the cockpit ceiling had at first blinded the pilots with smoke, leaving them to rely on instruments to divert the plane, en route from New York to Geneva, to an emergency landing at Halifax Airport in the Canadian province of Nova Scotia. But the fire raging above and behind the pilots, intense enough to melt the aluminum of the flight deck, consumed wiring harness after wiring harness, cutting power to vital flight control systems. With no way to control the plane, the MD-11 hit the Atlantic ocean about six miles off the coast. All 229 souls were lost.

It would take months to recover and identify the victims. The 350-g crash broke the plane into two million pieces which would not reveal their secrets until much later. But eventually, the problem was traced to a cascade of failures caused by faulty wiring in the new in-flight entertainment system that spread into the cockpit and doomed the plane. A contributor to these failures was the type of insulation used on the plane’s wiring, blamed by some as the root cause of the issue: the space-age polymer Kapton.

No matter where we are, we’re surrounded by electrical wiring. Bundles of wires course with information and power, and the thing that protects us is the thin skin of insulation over the conductor. We trust these insulators, and in general our faith is rewarded. But like any other engineered system, failure is always an option. At the time, Kapton was still a relatively new wonder polymer, with an unfortunate Achilles’ heel that can turn the insulator into a conductor, and at least in the case of flight 111, set a fire that would bring a plane down out of the sky.

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How to Test a B-52 Against EMP: Project ATLAS-I

Audacious times generate audacious efforts, especially when national pride and security are perceived to be at stake. Such was the case in the 1950s and 1960s, with the Space Race that started with a Russian sphere whizzing around the planet and ended with Neil Armstrong’s footprint on the Moon. But at the same time, other efforts were underway to answer big questions of national import, such as determining how durable the United States’ strategic assets were, and whether they could withstand the known effects of electromagnetic pulse (EMP), a high-intensity burst of electromagnetic energy that could potentially disable a plane in flight. Finding out just what an EMP could do to a plane would take big engineering and a large forest’s worth of trees.

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