text
stringlengths 301
426
| source
stringclasses 3
values | __index_level_0__
int64 0
404k
|
|---|---|---|
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
interfaces, allowing the next layer down in the data center network — the top-of-rack network that connects the server cards to each other and to the leaf network — to use optical fiber. This will put the top-of-rack network on track to keep up with the exponentially growing demand for bandwidth | medium | 2,590 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
between server cards. That is only the start. As the progress of silicon photonics continues, the evolution will lead to even more innovation, as optical interconnect becomes the medium for connections between packages on the server cards themselves. Fabricating Optics on Silicon Wafers These | medium | 2,591 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
changes are all predicated upon implementing critical optical components on silicon wafers, in processes that can be mass produced in 300mm wafer fabs. This has been a core research, development and productization objective for Intel. A central component, and the one that is critical to | medium | 2,592 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
manufacturing in high volume, is the light source. Intel recently published work on an eight-wavelength distributed feedback (DFB) laser array that is fully integrated on a silicon wafer and delivers excellent output power uniformity and wavelength spacing uniformity. The eight-wavelength DFB array | medium | 2,593 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
was designed and fabricated using Intel’s commercial 300 mm hybrid silicon photonics platform, which is used today to manufacture production optical transceivers in volume. The same hybrid platform is used to build on-die semiconductor optical amplifiers that boost the amplitude of light on a | medium | 2,594 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
photonic IC (PIC). Intel fabricates other critical components using more common 300mm wafer-processing techniques and materials. Optical silicon waveguides allow us to move light precisely around on the surface of a PIC, much as copper interconnect moves electrical signals. Microring resonators | medium | 2,595 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
allow a particular wavelength of light to be selected out from the mixture of wavelengths in a waveguide and modulated in a transmitter or sent to a detector in a receiver. Optical Compute Interconnect The next step in integration, however, will prove a deeper level of innovation for data centers. | medium | 2,596 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
It will be possible to integrate the two dies of the optical interface with compute dies on a single package. This means the compute fabric within servers can be interconnected via optical links. This is called Optical Compute Interconnect, and it will have immediate impacts. First, it will break | medium | 2,597 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
open the approaching pin count and power barrier that will limit the bandwidth in and out of a package. These physical limitations are beginning to constrain how much aggregate interconnect bandwidth we can sustain using electrical interfaces. But coming out of the package directly with optical | medium | 2,598 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
fibers opens the possibility of far greater aggregate bandwidth across the package boundary. We can keep ahead of the exponentially growing bandwidth appetite of processing packages with their growing numbers of compute cores. Second, we can benefit from the remarkable ability of optical | medium | 2,599 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
interconnect to conserve energy. By transitioning to optical fiber, the frequency-dependent channel loss of electrical channels is eliminated. Intel Labs research roadmap targets energy efficiency improvements while increasing bandwidth per fiber — targeting 1 pJ/bit energy efficiency with a | medium | 2,600 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
per-fiber bandwidth of 1 Tbit/s. As we look further down the research path, Intel Labs has a university research center with even more aggressive targets of 0.25 pJ/bit energy efficiency and bandwidth per fiber of 4 Tbits/s. So while we are solving an increasingly critical bandwidth problem, we are | medium | 2,601 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
also significantly reducing the energy-per-bit cost of moving data between packages. Innovation But there is one more remarkable characteristic of optical interconnect that now comes into the spotlight. Once you launch a light wave into an optical fiber, it keeps going, with only slightly | medium | 2,602 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
attenuated over distance. This means that the optical interconnect between packages on a server board needn’t stop after tens of centimeters. It can keep going for over 100 meters. This physical characteristic raises very interesting possibilities for the way data in the compute fabric may | medium | 2,603 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
communicate across board boundaries. From the top-of-rack network to, ultimately, server computing fabric, the silicon photonic components that Intel is researching and developing today open the opportunity for profound improvements in data center bandwidth, energy, and organization. We stand at a | medium | 2,604 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
fascinating threshold. For a more detailed discussion of this technology, please see two presentations at the 2022 Hot Interconnects Conference, Transitioning from Electrical to Optical I/O and Highly Integrated 4 Tbps Silicon Photonic IC for Compute Fabric Connectivity. These presentations are | medium | 2,605 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
available on the Hot Interconnects website. Notes & Disclaimers: Intel technologies may require enabled hardware, software or service activation. Your costs and results may vary. You may not use or facilitate the use of this document in connection with any infringement or other legal | medium | 2,606 |
Connectivity, Silicon, Photonics, Technical Analysis, Technews.
analysis concerning Intel products described herein. You agree to grant Intel a non-exclusive, royalty-free license to any patent claim thereafter drafted which includes subject matter disclosed herein. No license (express or implied, by estoppel or otherwise) to any intellectual property rights is | medium | 2,607 |
Nanotechnology, Nanophysics, Technology, Future.
Journey to the world of nanophysics and nanotechnology Hold onto your hats, dear readers, because we’re about to embark on a whimsical journey into the mesmerizing world of nanotechnology and nanophysics. These fields of science and engineering are like fairy tales come to life, where scientists | medium | 2,609 |
Nanotechnology, Nanophysics, Technology, Future.
work their magic at the tiniest scales imaginable, manipulating materials and devices atom by atom. So, gather ‘round as we uncover the enchanting secrets of these tiny wonders! Nanotechnology: Tiny Tech with Gigantic Potential Imagine a world where everything is one billionth of a meter in size — | medium | 2,610 |
Nanotechnology, Nanophysics, Technology, Future.
that’s nanotechnology for you! To put things in perspective, your average human hair is about 50,000 to 100,000 nanometers wide. At this minuscule scale, materials behave in peculiar ways, showcasing extraordinary properties and possibilities. Applications of Nanotechnology: A Dash of Magic | medium | 2,611 |
Nanotechnology, Nanophysics, Technology, Future.
Medicine: Nanotechnology isn’t just science; it’s medicine’s favorite fairy godmother. It can create nanoparticles that seek out specific cells, deliver medicine right where it’s needed, and even play detective by spotting early diseases. Imagine less suffering and fewer side effects! Electronics: | medium | 2,612 |
Nanotechnology, Nanophysics, Technology, Future.
Ever wonder how your gadgets keep getting smaller and smarter? Nanotechnology is the answer! It helps shrink transistors, leading to more powerful chips. It even introduces us to quantum dots, which promise dazzling displays and energy-efficient solar panels. Materials: Nanomaterials are the | medium | 2,613 |
Nanotechnology, Nanophysics, Technology, Future.
Cinderella stories of the materials world. Think carbon nanotubes and graphene — they’re ultra-strong, feather-light, and conduct electricity like no other. The aerospace and electronics industries are swooning over them! Energy: Saving the environment with a sprinkle of nanotech magic! | medium | 2,614 |
Nanotechnology, Nanophysics, Technology, Future.
Nanomaterials are making batteries better, supercharging solar panels, and paving the way for more efficient fuel cells. Say hello to a greener future! Nanophysics: Unraveling the Mysteries of the Tiny Universe Nanophysics is like the wizardry of physics, where scientists unlock the secrets of | medium | 2,615 |
Nanotechnology, Nanophysics, Technology, Future.
matter and phenomena at the nanoscale. It’s where the laws of quantum mechanics reign supreme, giving us insights into the peculiar behavior of materials when they’re miniaturized. Key Concepts in Nanophysics: The Magic Spells Quantum Mechanics: In the land of the tiny, classical physics takes a | medium | 2,616 |
Nanotechnology, Nanophysics, Technology, Future.
backseat, and quantum mechanics takes center stage. Particles like electrons start acting like both waves and particles, and probability becomes the name of the game. Quantum Tunneling: Nanoscale particles can do the impossible — they can “tunnel” through energy barriers that would baffle a | medium | 2,617 |
Nanotechnology, Nanophysics, Technology, Future.
classical physicist. This trick is put to use in gadgets like tunnel diodes and scanning tunneling microscopes. Quantum Confinement: When particles are kept in cozy, small spaces like quantum dots or nanowires, their energy levels get quantized. This leads to mesmerizing optical and electronic | medium | 2,618 |
Nanotechnology, Nanophysics, Technology, Future.
properties, perfect for all sorts of nanodevices. Nanoscale Sensors: Nanophysics gives birth to the most delicate and perceptive sensors you can imagine. They can detect single molecules or even individual atoms, a feat that has applications in biology, environmental monitoring, and beyond. | medium | 2,619 |
Nanotechnology, Nanophysics, Technology, Future.
Challenges and Ethical Quests Of course, like any good tale, there are challenges on this quest. Safety concerns, environmental impacts, and ethical dilemmas pop up, especially when nanoparticles find their way into consumer products and medicine. Brave researchers and wise regulators must work | medium | 2,620 |
Nanotechnology, Nanophysics, Technology, Future.
together to ensure that our magic doesn’t get out of control. As we bid adieu to our whimsical journey through the realms of nanotechnology and nanophysics, we’re reminded that magic is real, but it comes with great responsibility. These fields offer promises of innovation, improved health, and a | medium | 2,621 |
Aviation, Technology, Hungary, United Kingdom, History.
HA-LAJ lies in a field in Oxfordshire, UK, after its crash landing. (AAIB) On the 28th of August 1993, fire crews at RAF Weston-on-the-Green in Oxfordshire, England responded to the crash of an unusual airplane — a Soviet-designed Antonov An-28 twin turboprop, which had been chartered by a Royal | medium | 2,623 |
Aviation, Technology, Hungary, United Kingdom, History.
Air Force parachuting club for the purpose of carrying skydivers. Shortly after takeoff with two Russian pilots and 17 parachutists on board, the crew attempted to retract the flaps, only for a bizarre malfunction to occur, as both engines failed at the very instant the flap lever was selected. | medium | 2,624 |
Aviation, Technology, Hungary, United Kingdom, History.
With only seconds to react to the unbelievable failure, the captain managed to steer the Antonov to a safe crash landing in a cornfield nearby, saving the lives of everyone on board. Although the plane was written off, nobody was seriously injured. The incident presented Britain’s Air Accident | medium | 2,625 |
Aviation, Technology, Hungary, United Kingdom, History.
Investigation Branch with a rare opportunity to investigate the crash of a Soviet aircraft type on British soil, just a year and a half after the collapse of the USSR. Indeed, the story they uncovered was a strange one — from the murky chain of events that led to the An-28’s unapproved modification | medium | 2,626 |
Aviation, Technology, Hungary, United Kingdom, History.
for parachuting, to the plane’s simultaneous registration in two different countries, to the baffling electrical fault that caused the crash. And at the root of it all was a design decision that left investigators scratching their heads, a single point of failure that made the An-28 uniquely | medium | 2,627 |
Aviation, Technology, Hungary, United Kingdom, History.
vulnerable. How had the design ever passed muster? And why did the design seemingly change in between the original drawings and the actual production of the aircraft? Without access to the details of the design process, investigators were left to speculate, but what they wrote nevertheless provides | medium | 2,628 |
Aviation, Technology, Hungary, United Kingdom, History.
a fascinating window into British experts’ early post-Cold War opinions on Soviet aircraft. ◊◊◊ RAF Weston-on-the-Green is used by the RAF for both military and sport parachuting. (Richard Flagg) Built in 1916 at the height of WWI, RAF Weston-on-the-Green is a grass airstrip belonging to the Royal | medium | 2,629 |
Aviation, Technology, Hungary, United Kingdom, History.
Air Force, located near the town of Bicester in Oxfordshire, England. No aircraft are based there today, but the field has long been used as a practice drop zone by the Parachute Training School out of nearby RAF Brize Norton, the United Kingdom’s largest airbase. The airfield is also used for the | medium | 2,630 |
Aviation, Technology, Hungary, United Kingdom, History.
same purpose by the Royal Air Force Sports Parachuting Association, or RAFSPA, which provides a framework for RAF members to engage in competitive and sport parachuting (as opposed to parachuting for military purposes). Although up-to-date information is hard to find, this was historically done | medium | 2,631 |
Aviation, Technology, Hungary, United Kingdom, History.
using civilian aircraft either based at Weston-on-the-Green or hired from elsewhere. In late August 1993, RAFSPA intended to host a special parachuting event at RAF Weston-on-the-Green, for which the club required the services of an aircraft capable of operating out of the grass airstrip while | medium | 2,632 |
Aviation, Technology, Hungary, United Kingdom, History.
carrying up to 17 parachutists, who would jump from airplane in flight. For these purposes, RAFSPA hired a company called Avia Special Ltd., which was to act as a broker between the club and the operator of a qualifying aircraft. However, Avia Special was unable to find any aircraft in the United | medium | 2,633 |
Aviation, Technology, Hungary, United Kingdom, History.
Kingdom that met RAFSPA’s requirements and were available on the specified dates. Instead, Avia Special began looking abroad, and through some sequence of events that remains unclear, they became aware of a Hungarian company called G92 Commerce that was conducting parachute jumps out of a | medium | 2,634 |
Aviation, Technology, Hungary, United Kingdom, History.
Soviet-built Antonov An-28. The An-28 was featured on a USSR postage stamp. (Public domain image) The An-28 is a high-wing, twin turboprop aircraft with a distinctive double tail, capable of carrying up to 18 passengers or 1,750 kg of cargo. In terms of niche, its closest Western equivalents are | medium | 2,635 |
Aviation, Technology, Hungary, United Kingdom, History.
probably the DHC-6 Twin Otter and the Short Skyvan. The origins of the An-28 date back to the 1960s, when the Kyiv-based Antonov Design Bureau first produced the An-14, which had a similar cockpit, wing, and fuselage cross-section. The An-14 first entered service in 1966, and three years later | medium | 2,636 |
Aviation, Technology, Hungary, United Kingdom, History.
Antonov debuted the first An-28 prototype, which was essentially a stretched An-14 with better engines. However, a second prototype was not built until 1975, and in 1978 further delays were most likely incurred when it was decided to move production of the type to the PZL-Mielec factory in | medium | 2,637 |
Aviation, Technology, Hungary, United Kingdom, History.
neighboring Poland. Mass production did not actually begin until 1983, the first Polish-built airframe didn’t fly until 1984, and the type was finally certified by the USSR for civilian use only in 1986, fully 17 years after the first flight of the prototype. Just under 200 airframes were built | medium | 2,638 |
Aviation, Technology, Hungary, United Kingdom, History.
before the USSR collapsed five years later. Watch as the accident aircraft is assembled on site in Antarctica, then takes off on skis! (Antonov Aircraft Company) The particular An-28 that would become the star of this story was built in 1988 with the registration CCCP-28778, and was immediately | medium | 2,639 |
Aviation, Technology, Hungary, United Kingdom, History.
transferred to the Petrozavodsk branch of the Leningrad Board of Civil Aviation, itself a branch of the Soviet state aviation company Aeroflot. It’s not possible to track everything it was used for between 1988 and 1993, but it apparently saw a wide variety of applications. Sometime in the late | medium | 2,640 |
Aviation, Technology, Hungary, United Kingdom, History.
1980s CCCP-28778 was transported by ship to Antarctica, where it was fitted with skis, assembled on site, and tested for use transporting people and goods between bases. Information about this endeavor is hard to find but indications are that the An-28 proved unsuitable for the Antarctic | medium | 2,641 |
Aviation, Technology, Hungary, United Kingdom, History.
environment, possibly due to its lack of range, and it was shipped back. Following the collapse of the USSR in 1991, there is a period of uncertainty as to the ownership of the plane. The accident report states that the certificate of registration continued to list the Leningrad Board of Civil | medium | 2,642 |
Aviation, Technology, Hungary, United Kingdom, History.
Aviation as the sole owner through the time of the accident in 1993, but this obviously can’t be true because this entity was dissolved in 1992. Records available online indicate that it was briefly in the possession of Archangelsk Airlines, which later became Aeroflot Nord, now known as SmartAvia. | medium | 2,643 |
Aviation, Technology, Hungary, United Kingdom, History.
However, the only change to its official registration document occurred when someone crossed out the “CCCP” identifier and hand-wrote “RA” for Russia instead. In actuality, in May 1993 the aircraft was sub-leased with crew to a Budapest-based company called G92 Commerce, which in turn had an | medium | 2,644 |
Aviation, Technology, Hungary, United Kingdom, History.
agreement with the Hungarian Aeronautical Association in which the latter would act as the operator. The aircraft was then re-registered in Hungary with the registration HA-LAJ, but the Russian authorities were never informed and the aircraft remained on their books as RA-28778, rendering the | medium | 2,645 |
Aviation, Technology, Hungary, United Kingdom, History.
subsequent Hungarian registration technically invalid. Personnel load an An-28 through its rear clamshell doors. Normally only the left door is opened for passenger embarkation, as shown in this picture. (Wikimedia user Игоревич) Sometime after HA-LAJ’s registration in Hungary, Avia Special | medium | 2,646 |
Aviation, Technology, Hungary, United Kingdom, History.
contacted G92 Commerce to arrange for the use of the aircraft between August 27th and September 6th for the RAFSPA parachuting event at Weston-on-the-Green. By then the aircraft had already been modified for parachuting, by folding the passenger seats against the walls and removing the rear access | medium | 2,647 |
Aviation, Technology, Hungary, United Kingdom, History.
doors. This pair of doors was normally used for ground boarding and opened in a clamshell format, but on HA-LAJ they had been physically removed from the airplane to facilitate the parachutists’ mid-air disembarkation. Subsequently, on August 27th the aircraft departed Budapest under the command of | medium | 2,648 |
Aviation, Technology, Hungary, United Kingdom, History.
two Russian pilots who were presumably employed by the aircraft’s Russian owner. In the left seat was 40-year-old Captain Sergei Suskin, who had about 9,400 flying hours including 1,200 on the An-28. I was not able to find the name of the First Officer, but he was 26 years old and had 2,310 total | medium | 2,649 |
Aviation, Technology, Hungary, United Kingdom, History.
hours, including 510 on type. After stopping for fuel in Maastricht, Netherlands, HA-LAJ landed in Maidenhead, UK for a customs inspection, then flew onward to Weston-on-the-Green, arriving at around 15:30 that afternoon. The parachuting event itself got underway at 8:30 the following morning, when | medium | 2,650 |
Aviation, Technology, Hungary, United Kingdom, History.
HA-LAJ took off from the grass field with its first load of parachutists. The seating arrangement was ad-hoc, as the parachutists sat on the floor of the cabin with no particular restraint. Some flights also included a parachute club official who observed the crew to confirm that they were | medium | 2,651 |
Aviation, Technology, Hungary, United Kingdom, History.
following the provisions of the British Parachute Association Operations Manual. In each case, once everyone was on board, the aircraft would take off, climb out to the west, turn around, and cross back over the airfield heading north, at which time the parachutists would jump one after another | medium | 2,652 |
Aviation, Technology, Hungary, United Kingdom, History.
through the An-28’s rear access door. The aircraft would then come back around and land on the same runway from which it took off, with a total airborne time of only about 15 minutes. HA-LAJ as it would have appeared around the time of the accident. (Sabok Balázs) Twelve such flights, each carrying | medium | 2,653 |
Aviation, Technology, Hungary, United Kingdom, History.
up to 17 parachutists, proceeded beautifully. It was, of course, the unlucky 13th flight on which the real story began. With Captain Suskin at the controls and 17 people in the back — there was no observer this time — the aircraft departed the grass runway 36 as it had on each previous sortie, then | medium | 2,654 |
Aviation, Technology, Hungary, United Kingdom, History.
began its regular climb. The after takeoff checks on the An-28 were rather simple as the aircraft does not have retractable landing gear. The only significant configuration change required was to retract the flaps, which were extended on takeoff in order to boost lift at low speeds. Although a | medium | 2,655 |
Aviation, Technology, Hungary, United Kingdom, History.
couple of intermediate positions were available, the pilots of HA-LAJ didn’t need them; instead, at around 500 feet above the ground, Suskin normally had his First Officer move the flaps straight from the fully extended position to fully retracted, while he pitched down to increase speed. Although | medium | 2,656 |
Aviation, Technology, Hungary, United Kingdom, History.
most aircraft this size have a fully mechanical flap lever, on the An-28 this would have been done using an electric flap switch. Indeed, just as they had already done 12 times that day, at 500 feet Suskin called for flaps up, and the First Officer reached for the electric flap switch, cycling it | medium | 2,657 |
Aviation, Technology, Hungary, United Kingdom, History.
three times in rapid succession to bring the flaps all the way back to the fully retracted position. It was at that moment, just as the flaps started retracting, that all hell broke loose. ◊◊◊ How electrical grounding works on a moving vehicle. The symbol of the triple line is used to represent a | medium | 2,658 |
Aviation, Technology, Hungary, United Kingdom, History.
grounding point on all the diagrams in this article. (Ted Mortensen) To understand what happened at that precise moment, we need to go back to basics, starting with electrical systems — that is, not just the An-28’s electrical system, but any battery-powered electrical system. That’s because, when | medium | 2,659 |
Aviation, Technology, Hungary, United Kingdom, History.
you get down to it, the system that (for instance) retracts the An-28’s flaps is not fundamentally different from a basic circuit that you might build in a grade school science class. In any such setup, negatively charged electrons want to flow from the negative end of the battery to the positive | medium | 2,660 |
Aviation, Technology, Hungary, United Kingdom, History.
end, so if you connect those two ends to one another with a conductive material — such as a wire — you will complete a circuit, through which the electrons will flow as a current. Various fun devices can then be added to this circuit in order to put the electrons to work as they pass by. A light | medium | 2,661 |
Aviation, Technology, Hungary, United Kingdom, History.
bulb would be the classic example. However, as the constructors of early telegraph systems discovered, when building a very large circuit it takes a lot of wire to bring the electrons all the way from the battery to the place where you want them to do work, and then all the way back again | medium | 2,662 |
Aviation, Technology, Hungary, United Kingdom, History.
afterward. Fortunately, those early pioneers of the telegraph discovered that you don’t need the return wire as long as the end of the outbound wire and the corresponding terminal of the power source (in our case a battery) are connected to the same physical object, which for telegraph lines was | medium | 2,663 |
Aviation, Technology, Hungary, United Kingdom, History.
the planet Earth itself. That’s why we call this technique “grounding.” On moving vehicles, including both cars and aircraft, it’s obviously not possible to connect electrical circuits through the physical ground. Instead, circuits on such vehicles are “grounded” via the vehicle chassis. Therefore, | medium | 2,664 |
Aviation, Technology, Hungary, United Kingdom, History.
when a particular circuit is energized, the electrons will flow from the battery, down the wire to the device in question, and thence into the chassis, through which the electrons are conducted straight back to the opposite terminal of the battery, which is also connected to the chassis.* Should | medium | 2,665 |
Aviation, Technology, Hungary, United Kingdom, History.
this critical connection between the wire and the chassis be disrupted, the circuit will become “ungrounded,” and the current will seek other routes back to the opposite terminal — which might be through your body if you simultaneously touch the chassis and the end of the ungrounded wire, so don’t | medium | 2,666 |
Aviation, Technology, Hungary, United Kingdom, History.
do that. *[Note: Technically the electrons flow the other way — from the negative terminal, through the chassis, up through the grounding point, and back down the wire to the positive terminal. But that’s pretty spooky, and it makes no practical difference, so we normally pretend that the current | medium | 2,667 |
Aviation, Technology, Hungary, United Kingdom, History.
flows the other way.] How the current should flow through the flap operating system under normal conditions. (AAIB, annotations mine) On the An-28, the electrically actuated flap system drew power from a 27-volt battery. Moving the electric flap switch to any of its various positions would complete | medium | 2,668 |
Aviation, Technology, Hungary, United Kingdom, History.
a circuit, causing current to flow from the battery and through the flap operating solenoids in the manner corresponding to the selected position. This current would then go to ground via a terminal block called A6X1, which served as a common endpoint for a number of different wires from several | medium | 2,669 |
Aviation, Technology, Hungary, United Kingdom, History.
circuits. After reaching the A6X1 terminal block, the normal current path was through one of two wires, called M01 and M02 respectively, which both connected to a single “grounding screw.” This screw was in turn attached to the aircraft chassis, allowing the current to enter the chassis and return | medium | 2,670 |
Aviation, Technology, Hungary, United Kingdom, History.
to the opposite terminal of the battery. A feathered vs. unfeathered propeller. (SkyBrary) However, the flaps were not the only system connected to ground via terminal block A6X1. The other major system utilizing this terminal block was the An-28’s propeller autofeather mechanism. As I’ve discussed | medium | 2,671 |
Aviation, Technology, Hungary, United Kingdom, History.
in many previous articles, the propellers on turboprop aircraft have adjustable blade pitch. When the edges of the blades are in line with the propeller’s plane of rotation, they don’t take any bite out of the air; they will spin freely with little resistance. Increasing the angle of the blades | medium | 2,672 |
Aviation, Technology, Hungary, United Kingdom, History.
will cause them to start taking a bigger bite out of the air, forcing air backward to generate thrust. But if the blade angle increases so far that the edges of the blades are perpendicular to the plane of rotation, then the propeller will no longer be able to force any air backward, and thrust | medium | 2,673 |
Aviation, Technology, Hungary, United Kingdom, History.
again drops to zero. This is known as the “feathered” position (see above). If a turboprop engine were to fail in flight, the turbine would stop powering the propeller. If the blades are still angled to produce thrust, then instead of the blades taking a bite out of the air, the oncoming air will | medium | 2,674 |
Aviation, Technology, Hungary, United Kingdom, History.
start to take a bite out of the blades, so to speak, driving the propeller, and thus the turbine, in reverse. This causes a lot of drag that negatively affects performance, so in order to prevent this from happening, turboprop aircraft are equipped with an autofeather system that automatically | medium | 2,675 |
Aviation, Technology, Hungary, United Kingdom, History.
rotates the blades to the feathered position in the event of an engine failure. This can also be done by the pilots using a cockpit switch, should the need arise. Once the blades are feathered, the oncoming airflow will no longer be able to get enough leverage to drive the propeller, eliminating | medium | 2,676 |
Aviation, Technology, Hungary, United Kingdom, History.
the excess drag. How the current should flow through the feathering circuit during manual or automatic propeller feathering. This isn’t “normal” operation because normally no propellers should feather in flight. (AAIB, annotations mine) On the An-28, the autofeather system could be activated by | medium | 2,677 |
Aviation, Technology, Hungary, United Kingdom, History.
closing one or both of two switches, designated 7S19 and 7S20, respectively, one for each propeller. (Henceforth, I’ll be calling these the “feathering switches.”) The switches each had two terminals: a permanently non-energized terminal that was normally closed (i.e. making contact), and a | medium | 2,678 |
Aviation, Technology, Hungary, United Kingdom, History.
normally open terminal, which if it were to close would energize the feathering circuits. These switches controlled power to the feathering circuits regardless of whether the feathering command was automatic or manual. Should either of these circuits be completed, power would flow from the battery, | medium | 2,679 |
Aviation, Technology, Hungary, United Kingdom, History.
through the activated switch(es), and down a wire to the 7-K6 feathering relays, which transmitted the feather command to the blade pitch actuation system. After that, the current went to ground in one of two separate locations, one for each of the two identical circuits (depicted above). However, | medium | 2,680 |
Aviation, Technology, Hungary, United Kingdom, History.
when the feathering circuits are not energized, which is essentially all of the time, the normally closed ends of both feathering switches are connected via wires to the A6X1 terminal block, and thence to ground via that terminal block’s grounding screw, described previously. These wires should | medium | 2,681 |
Aviation, Technology, Hungary, United Kingdom, History.
never under any circumstances be energized, because when the feathering system is operational the current will bypass them, and when it is not, there should be no current present. So why was it necessary to ground the normally closed side of the switches, even though there wasn’t supposed to be any | medium | 2,682 |
Aviation, Technology, Hungary, United Kingdom, History.
current in the circuit when this side of the switch was closed? The answer, as far as I can tell, is that it’s simply good practice to ground any exposed conductor. If the normally closed side of the switch was left connected to nothing, it could serve as an entry point for electromagnetic | medium | 2,683 |
Aviation, Technology, Hungary, United Kingdom, History.
interference, potentially resulting in uncommanded feathering of one or more propellers. You can think of that exposed conductor like a lightning rod sticking out into space, inviting random energy sources to induce a current into the feathering circuit. Grounding the normally closed side of the | medium | 2,684 |
Aviation, Technology, Hungary, United Kingdom, History.
switch was therefore a prudent move. As for where to ground it, the A6X1 terminal block was probably chosen just because it was nearby. All of this may be complicated to visualize, but hopefully the attached diagrams are helping. Studying them carefully should make it much easier to understand the | medium | 2,685 |
Aviation, Technology, Hungary, United Kingdom, History.
failure that was about to occur. Now, with all this in mind, can you guess where this system had a potential single point of failure? ◊◊◊ If you guessed the grounding screw on terminal block A6X1, then congratulations, you’re better at this than whoever designed the An-28’s electrical system. The | medium | 2,686 |
Aviation, Technology, Hungary, United Kingdom, History.
grounding screw was, in fact, simply a screw, and like any screw mounted in a high-vibration environment, it was capable of loosening over time. And the looser it got, the less effectively it contacted the chassis. In fact, if the screw was loose enough, then the resistance between the screw and | medium | 2,687 |
Aviation, Technology, Hungary, United Kingdom, History.
the chassis would become so great that this would no longer represent the optimal current path. The “hair in pipe” analogy for electrical resistance. (Wikimedia user Sbyrnes321) Electrical resistance is the opposite of conductance. The higher an object’s resistance, the harder it is to push a | medium | 2,688 |
Aviation, Technology, Hungary, United Kingdom, History.
current through that object. The Wikipedia page on resistance and conductivity has a great metaphor for this, which I will shamelessly steal. If you have a water pipe with water flowing through it at a given rate, then that pipe becomes partially blocked with hair, a higher water pressure is | medium | 2,689 |
Aviation, Technology, Hungary, United Kingdom, History.
required to maintain the same flow rate. Extrapolating further, if another path for the water exists that has a more favorable pressure-to-flow-rate ratio, then the majority of the water will start going that way instead. Electricity is much the same way: the electrons will flow down all available | medium | 2,690 |
Aviation, Technology, Hungary, United Kingdom, History.
paths at a rate inversely proportional to their relative resistance. So, if the grounding screw on the A6X1 terminal block were to pull out of the chassis, then there would be an air gap between the screw and the chassis, which has a high resistance. Furthermore, if that resistance is high enough, | medium | 2,691 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.