What On Earth Is A Pickle Fork And Why Is It Adding To Boeing’s 737 Woes?

September 30, 2019 by Jenny List 88 Comments

It’s fair to say that 2019 has not been a good year for the aircraft manufacturer Boeing, as its new 737 MAX aircraft has been revealed to contain a software fault that could cause the aircraft to enter a dive and crash. Now stories are circulating of another issue with the 737, some of the so-called “Pickle forks” in the earlier 737NG aircraft have been found to develop cracks.

It’s a concerning story and there are myriad theories surrounding its origin but it should also have a reassuring angle: the painstaking system of maintenance checks that underpins the aviation industry has worked as intended. This problem has been identified before any catastrophic failures have occurred. It’s not the story Boeing needs at the moment, but they and the regulators will no doubt be working hard to produce a new design and ensure that it is fitted to aircraft.

The Role of the Pickle Fork

For those of us who do not work in aviation though it presents a question: what on earth is a pickle fork? The coverage of the story tells us it’s something to do with attaching the wing to the fuselage, but without a handy 737 to open up and take a look at we’re none the wiser.

Fortunately there’s a comprehensive description of one along with a review of wing attachment technologies from Boeing themselves, and it can be found in one of their patents. US9399508B2 is concerned with an active suspension system for wing-fuselage mounts and is a fascinating read in itself, but the part we are concerned with is a description of existing wing fixtures on page 12 of the patent PDF.

A cross-section of the aircraft wing fixing, in which we've highlighted the role of the pickle forks. (Boeing) — A cross-section of the aircraft wing fixing, in which we’ve highlighted the role of the pickle forks. (Boeing)

The pickle fork is an assembly so named because of its resemblance to the kitchen utensil, which attaches firmly to each side of the fuselage and has two prongs that extend below it where they are attached to the wing spar.

For the curious engineer with no aviation experience the question is further answered by the patent’s figure 2, which provides a handy cross-section. The other wing attachment they discuss involves the use of pins, leading to the point of the patented invention. Conventional wing fixings transmit the forces from the wing to the fuselage as a rigid unit, requiring the fuselage to be substantial enough to handle those forces and presenting a problem for designers of larger aircraft. The active suspension system is designed to mitigate this, and we’d be fascinated to hear from any readers in the comments who might be able to tell us more.

We think it’s empowering that a science-minded general public can look more deeply at a component singled out in a news report by digging into the explanation in the Boeing patent. We don’t envy the Boeing engineers in their task as they work to produce a replacement, and we hope to hear of their solution as it appears.

[via Hacker News]

[Header image: AMX Boeing 737 XA-PAM by Jean-Philippe Boulet CC-BY 3.0]

Steam Bike Rocks It Old-School

September 20, 2019 by Lewin Day 22 Comments

Petrol engines dominate the world of the automobile, while electric propulsion races to take an ever larger market share. Despite this, some still hold a flame for steam power. Such aficionados would hold this build in high regard, from the recent past of 2014.

The bike is of a recumbent design, featuring a relaxed riding position well suited to the sophisticated nature of a steam-powered vehicle. Sporting a wooden frame, the build carries a strong steampunk aesthetic. The flash boiler packs 100 feet of copper pipe, and there’s an electric pump and controller to handle water delivery from the stylish brass tank. The setup is capable of producing steam within 30 seconds of startup. Motive power is courtesy of a 1.5 inch bore single-cylinder steam engine, connected to the rear wheel via a belt drive.

There’s something intoxicating about the sounds and smells of a working steam engine, though the threat of catastrophic burns does temper the excitement just a touch. Steam power isn’t going away any time soon – and it’s not just limited to transport applications, either. Video after the break.

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Monster Bush Plane Is A One-Off Engineering Masterpiece

September 15, 2019 by Danie Conradie 36 Comments

All of us dream of reaching a point in life where we have the knowledge, skills, energy and resources to pull off builds that match our wildest dreams. [Mike Patey] is living that dream and with a passion for engineering and aviation that is absolutely infectious, he built Draco, the world’s most badass bush plane.

Draco started life as a PZL-104MA Wilga 2000, which already had impressive short take off and landing (STOL) capabilities for a 4 seater. Its original 300 hp Lycoming piston engine failed catastrophically in 2017, very nearly dumping [Mike] in Lake Utah. He decided it was a good excuse to start building his dream plane, and replaced the motor with a Pratt & Whitney PT6 turboprop engine, putting out a massive 680 hp.

Almost the entire plane was upgraded, and the engineering that went into it is awe-inspiring, especially considering that [Mike] did most of it himself. This includes a redesigned fuel system, enlarged wing and control surfaces, new avionics, oxygen system, upgraded landing gear and an array of lights. The wing tip landing lights are actually from a Boeing 737. [Mike] estimates that the upgrades cost somewhere in the region of a million US dollars. All the highlights of the build is documented in series of videos on [Mike]’s YouTube channel. What we would give for a personal workshop like that…

Try not to let your jaw hit the floor when watching the video after the break.

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Is It A Boat? Is It A Hammock? No, It’s Both!

September 13, 2019 by Jenny List 15 Comments

If you’re enjoying a Western Canadian summer, two of the best ways to do so involve a hammock, or a boat. Seeking to improve on this mighty duo with a hammock-boat combo, [Jarrett] describes his progress at Vancouver Hack Space.

The boat he chose was a one-person catamaran with an aluminium frame and what appear to be inflatable pontoons, while the hammock is one designed for a garden or patio with a steel tubular frame. A design goal was to not modify or destroy the structure of either item, so the challenge was to securely mount the two frames together. A variety of false starts involving bent steel or aluminium were tried, followed by a final success with the aluminium tubes reinforced with more tube inside them, and the hammock attached with U-bolts.

The testing took place on what appears to be a public lake, and the contraption floated well. When it had been pushed out to a landing stage our intrepid adventurer boarded the hammock — and promptly the whole edifice tipped itself over, depositing him in the drink. Further experimentation revealed that balance was critical, and a revised position could achieve a stable boarding. He paddles off into the sunset as you can see in the video below the break, though as his friends remind him, without his beer.

Commercial hammocks are surprisingly expensive for what they are. Don’t worry though, if you find them to be beyond your budget you can always make a frame for one yourself.

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Rideable Tank Tread: It’s A Monotrack Motorcycle That Begs You To Stop Very Slowly

September 11, 2019 by Danie Conradie 47 Comments

There will always be those of us who yearn for an iron steed and the wind through your hair. (Or over your helmet, if you value the contents of your skull.) If having fun and turning heads is more important to you than speed or practicality, [Make it Extreme] has just the bike for you. Using mostly scrapyard parts, they built a monotrack motorcycle — no wheels, just a single rubber track.

[Make it Extreme] are definitely not newcomers to building crazy contraptions, and as usual the entire design and build is a series of ingenious hacks complimented by some impressive fabrication skills. The track is simply a car tyre with the sidewalls cut away. It fits over a steel frame that can be adjusted to tension the track over a drive wheel and a series of rollers which are all part of the suspension system.

Power is provided by a 2-stroke 100cc scooter engine, and transmitted to the track through a drive wheel made from an old scuba tank. What puts this build over the top is that all of this is neatly located inside the circumference of the track. Only the seat, handlebars and fuel tank are on the outside of the track. The foot pegs are as far forward as possible, which helps keep your center of gravity when stopping. It’s not nearly as bad as those self-balancing electric monocycles, but planning stops well in advance is advisable.

While it’s by no means the fastest bike out there it definitely looks like a ton of fun. Build plans are available to patrons of [Make it Extreme], but good luck licensing one as your daily driver. If that’s your goal, you might want to consider adding a cover over the track between the seat and handlebars to prevent your khakis from getting caught on your way to the cubicle farm.

Continue reading “Rideable Tank Tread: It’s A Monotrack Motorcycle That Begs You To Stop Very Slowly” →

Fail Of The Week: Taking Apart A Tesla Battery

September 7, 2019 by Bryan Cockfield 86 Comments

It takes a lot of energy to push a car-sized object a few hundred miles. Either a few gallons of gasoline or several thousand lithium batteries will get the job done. That’s certainly a lot of batteries, and a lot more potential to be unlocked for their use than hurling chunks of metal around on wheels. If you have an idea for how to better use those batteries for something else, that’s certainly an option, although it’s not always quite as easy as it seems.

In this video, [Kerry] at [EVEngineering] has acquired a Tesla Model 3 battery pack and begins to take it apart. Unlike other Tesla batteries, and even more unlike Leaf or Prius packs, the Model 3 battery is extremely difficult to work with. As a manufacturing cost savings measure, it seems that Tesla found out that gluing the individual cells together would be less expensive compared to other methods where the cells are more modular and serviceable. That means that to remove the individual cells without damaging them, several layers of glue and plastic have to be removed before you can start hammering the cells out with a PEX wedge and a hammer. This method tends to be extremely time consuming.

If you just happen to have a Model 3 battery lying around, [Kerry] notes that it is possible to reuse the cells if you have the time, but doesn’t recommend it unless you really need the energy density found in these 21700 cells. Apparently they are not easy to find outside of Model 3 packs, and either way, it seems as though using a battery from a Nissan Leaf might be a whole lot easier anyway.

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Who Needs Four Wheels When You’ve Got A Gyro?

September 6, 2019 by Lewin Day 15 Comments

Your garden variety car generally comes with four wheels, plus a spare in the boot. It’s a number landed upon after much consideration, with few vehicles deviating from the norm. That doesn’t mean there aren’t other possibilities however, and [RCLifeOn] decided to experiment in just such a manner.

The result is a gyro-stabilized two-wheeled RC car, or as we might have put it, a motorcycle of sorts. A brushless motor drives the rear wheel, while steering up front is handled by a servo controlling the front wheel. A large spinning disc acts as a gyro in the center of the vehicle, and it’s all packaged in a simple 3D printed frame.

Results are impressive, with the gyro making a demonstrable difference to the vehicle’s performance. While it can be driven without the gyro enabled, it requires continual steering corrections to stay upright. With the gyro spun up, it rides much more like a bicycle, with few stability issues.

It’s a fun project, and a great way to learn about gyroscopic stability. Of course, there are great primers on the topic, too. Video after the break. Continue reading “Who Needs Four Wheels When You’ve Got A Gyro?” →