Once upon a time, bailing out of a plane involved popping open the roof or door, and hopping out with your parachute, hoping that you’d maintained enough altitude to slow down before you hit the ground. As flying speeds increased and aircraft designs changed, such escape became largely impossible.
Ejector seats were the solution to this problem, with the first models entering service in the late 1940s. Around this time, the United Kingdom began development of a new fleet of bombers, intended to deliver its nuclear deterrent threat over the coming decades. The Vickers Valiant, the Handley Page Victor, and the Avro Vulcan were all selected to make up the force, entering service in 1955 through 1957 respectively. Each bomber featured ejector seats for the pilot and co-pilot, who sat at the front of the aircraft. The remaining three crew members who sat further back in the fuselage were provided with an escape hatch in the rear section of the aircraft with which to bail out in the event of an emergency.
The RC world was changed forever by the development of the lithium-polymer battery. No longer did models have to rely on expensive, complicated combustion engines for good performance. However, batteries still lack the energy density of other fuels, and so flying times can be limited. Aiming to build a drone with impressively long endurance, [Игорь Негода] instead turned to hydrogen power.
With a wingspan of five meters, and similar length, the build is necessarily large in order to carry the hydrogen tank and fuel cell that will eventually propel the plane, which uses a conventional brushless motor for propulsion. Weighing in at 6 kilograms, plenty of wing is needed to carry the heavy components aloft. Capable of putting out a maximum of 200W for many hours at a time, the team plans to use a booster battery to supply extra power for short bursts, such as during takeoff. Thus far, the plane has flown successfully on battery power, with work ongoing to solve handling issues and determine whether the platform can successfully fly on such low power.
No matter what they’re flying, good pilots have a “feel” for their aircraft. They know instantly when something is wrong, whether by hearing a strange sound or a feeling a telltale vibration. Developing this sixth sense is sometimes critical to the goal of keeping the number of takeoff equal to the number of landings.
The same thing goes for non-traditional aircraft, like paragliders, where the penalty for failure is just as high. Staying out of trouble aloft is the idea behind this paraglider line tension monitor designed by pilot [Andre Bandarra]. Paragliders, along with their powered cousins paramotors, look somewhat like parachutes but are actually best described as an inflatable wing. The wing maintains its shape by being pressurized by air coming through openings in the leading edge. If the pilot doesn’t maintain the correct angle of attack, the wing can depressurize and collapse, with sometimes dire results.
Luckily, most pilots eventually develop a feel for collapse, sensed through changes in the tension of the lines connecting the wing to his or her harness. [Andre]’s “Tensy” — with the obligatory “McTenseface” surname — that’s featured in the video below uses an array of strain gauges to watch to the telltale release of tension in the lines for the leading edge of the wing, sounding an audible alarm. As a bonus, Tensy captures line tension data from across the wing, which can be used to monitor the performance of both the aircraft and the pilot.
There are a lot of great design elements here, but for our money, we found the lightweight homebrew strain gauges to be the real gem of this design. This isn’t the first time [Andre] has flown onto these pages, either — his giant RC paraglider was a big hit back in January.
For garden variety daily computing tasks, the floppy disk has thankfully been a thing of the past for quite some time. Slow, limited in storage and easily corrupted, few yearn for the format to return, even if there is some lingering nostalgia for the disks. As it turns out, though, there is still hardware that relies on floppies – namely, the Boeing 747-400, as The Register reports.
The news comes from the work of Pen Test Partners, who recently inspected a 747 being retired as a result of the coronavirus pandemic. The floppy disks are used to load navigational databases which need to be updated regularly, every 28 days. Engineers responsible for loading updates must perform the process manually on the ground.
Efforts have been made in some areas to replace the disks with more modern technology. As Aviation Today covered in 2014, legacy aircraft often require updates involving up to eight floppy disks, leading to slow updates that can cause flight delays. As anyone familiar with the reliability of floppy media knows, it only takes one bad disk to ruin everything. While retrofits are possible, it’s more likely that airlines will simply stick with the technology until the legacy airplanes are retired. Certifying new hardware for flight is a major cost that is difficult to justify when the current system still works.
They say that drummers make the best helicopter pilots, because to master the controls of rotary-wing aircraft, you really need to be able to do something different with each limb and still have all the motions coordinate with each other. The control complexity is due to the mechanical complexity of the swashplate, which translates control inputs into both collective and cyclical changes in the angle of attack of the rotor blades.
As [Tom Stanton] points out in his latest video, a swashplate isn’t always needed. Multicopters dispense with the need for one by differentially controlling four or more motors to provide roll, pitch, and yaw control. But thanks to a doctoral thesis he found, it’s also possible to control a traditional single-rotor helicopter by substituting flexible rotor hinges and precise motor speed control for the swashplate.
You only need to watch the slow-motion videos to see what’s happening: as the motor speed is varied within a single revolution, the tips of the hinged rotor blades lead and lag the main shaft in controlled sections of the cycle. The hinge is angled, which means the angle of attack of each rotor blade changes during each rotation — exactly what the swashplate normally accomplishes. As you can imagine, modulating the speed of a motor within a single revolution when it’s spinning at 3,000 RPM is no mean feat, and [Tom] goes into some detail on that in a follow-up video on his second channel.
A staple of today’s remote-controlled flight is the so-called FPV transmitter, allowing the pilot of a multirotor or other craft to see the world from onboard, as a pilot might do. It’s accessible enough that it can be found on toy multirotors starting at not much more than pocket money prices, and reliable enough that in its better incarnations it can send back high definition video at surprisingly long range.
In case you think of FPV flight as a recent innovation, the video below the break from [Larry Mitschke] should come as a revelation. In 1986 he was a bona-fide rockstar playing in a band, whose radio-controlled flight hobby led him into creating an FPV system for his planes and soaring above the Texas countryside at significant distance from his base while flying it watching a CRT screen.
The video is quite long but extremely watchable, all period footage with his narration here in 2020. We see his earliest experiments with a monochrome security camera and a video sender, and a whole host of upgrades until finally he can fly three miles from base with good quality video. 70 cm amateur TV makes an appearance with a steerable tracking antenna, he even makes a talking compass for when he loses himself. It’s an epic tale of hacking with what seems rudimentary equipment by our standards but was in fact the cutting edge of available video technology at a time when the state of the video art was moving rather fast. This is the work that laid the path for today’s $30 FPV toys, and for flying FPV from space.
For many of us who grew up in the 1970s, “VertiBird”, the fly-it-yourself indoor helicopter, was a toy that was begged for often enough that it eventually appeared under the Christmas tree. And more than a few of the fascinating but delicate toys were defunct by Christmas afternoon, victims of the fatal combination of exuberant play and price-point engineering. But now a DIY version of the classic toy flies again, this time with a more robust design.
To be fair to the designers at Mattel, the toy company that marketed VertiBird, the toy was pretty amazing. The plastic helicopter was powered by a motor located in the central base, which rotated a drive rod that ran through a stiff tether. Small springs in the base and at the copter acted as universal joints to transmit power to the rotor. These springs were the weak point in the design, especially the one in the base, often snapping in two.
[Luke J. Barker]’s redesign puts a tiny gear motor in the aircraft rather than in the base, something that wouldn’t have been feasible in the original. To address the problem of getting electrical power from the base to the aircraft, [Luke] eschewed an expensive slip ring and instead used a standard 3.5-mm audio jack and plug. The plug serves as an axle for the main gear in the base that powers the copter’s rotation; sadly, this version doesn’t tilt the aircraft mechanically to control backward and forward flight like the original. A pair of pots with 3D-printed levers control throttle and flight direction through an Arduino; see it in action in the video below.
These pages abound with rotorcraft builds, both helicopters and multirotor. We appreciate all manner of flying machines, but this one really takes us back.