TWO LEGS BAD
Thus it was that the rules of the GoFly Challenge, at least so far as they related to the allowable dimensions of the craft, would not allow for an upright adult-sized passenger compartment pitched between a pair of quadcopters using the 32” propellers that we’d selected at the outset… they burst the dimensional ‘bubble’. This had led in turn to a reduction in the overall size of the ‘telephone-box’ whereas for a while the immediate alternative was to stack one quadcopter upon the other and set them both above the overhead. Ultimately, and although the original test-flight and accompanying video did feature all eight propellers arrayed around the top by these means, this was discounted as a solution principally for the original structural reason that it would require a stiffer and heavier compartment along with an extensive and equally weighty undercarriage to prevent it from toppling over. When it came to travelling to the event itself, as transpires later in the story, it was also that much more difficult to transport.
For although the idea of being ‘teleported’ in an upright box has an enduring appeal, from the structural point of view it faced numerous challenges in itself. Conventional phone-boxes are not lightweight structures, and in fact the bulk of designs in the UK (and certainly those considered classics like for example the K8) were cast in parts in a factory in Glasgow as a set of cast-iron panels beside a dome and base. As the sides were essentially solid, especially in the ‘lead-light’ varieties designed by Giles Gilbert Scott, they incorporated effective shear-webs that prevented distortion by say twisting.
Twisting is not so much an issue with a cast-iron structure anchored to a concrete base, but would possibly adversely affect the flight of a twinned pair of drones separated by a vertical booth. We have touched on the relative fragility of the flight-control means, and these dictate that the drone’s structure be as rigid as possible. Departures from this law such as undue harmonic vibrations and flexing of components play havoc with the means of flight control, which involve as many as four hundred calculations per second as to what power to supply to each of the motors in order to facilitate motions in three axes beside three planes as well. In other words, when the controller commands an RPM alteration to alter what is called a ‘vector’ or force application in a specific direction, it expects this to be carried out precisely. If for example the increase of that power causes the motor to apply an unbridled twisting force to the point at which it is attached, then it will produce am altogether different vector and resultant motion.
Nor is there any feedback as to how or why this is happening i.e. the process is effectively blind so far as the controller is concerned. Upshot is though in all events that the airframe does not respond as programmed, which in turn leads to adverse feedback loops and a departure from stable flight. To complicate matters also there are GPS and compass inputs that have to be as expected ~ garbage in, garbage out ~ in order for things to go as well as expected. Things not going as well as expected, at least in our own experience, meant the airframe entering a sort of uncontrollable oscillation or ‘death spiral’ of increasing magnitude. All physical constructs (like the Tacoma Straits bridge or the Space Shuttle) are subject to unforeseen dynamics of the sort requiring ironing out through ~ albeit expensive if not life-threatening ~ experimentation.
In other words, like the earliest iterations of everything and not least computers, these remarkable flight-controllers where the Achilles’ Heel of electrical flight. They are best described in fact in more positive terms as the prima-donna’s of emerging aviation, in so far as when they do perform they do so spectacularly and beyond the limits of human capability, but cannot be wholly relied upon to do so: when they are good they are very very good, and when they are bad they are bad.
Thus it was that for a while we (or invariably I) would consider the obvious alternatives; and when it comes to alternatives there are more in eVTOL than in any other field except perhaps genetic manipulation. This is because multicopters are basically airframes to which any number of motors and propellers can be positioned in any number of locations. In fact among the most difficult aspect of persuading people of the viability of a particular layout is the counter-argument that you can now raise practically anything you want using the technology. Two brothers in Germany thus applied six motors to a fibreglass bath that they took flying down to the shops with at least one of them on board, whilst David Walliams in the UK would have the epic motor-vehicle Chitty Chitty Bang Bang rebuilt and fitted with four rotors in order that it really would fly for assembled school-children.
Eventually however it would ~ and will ~ come down to what proves mass-producible and acceptable at the same time. An example of a product that could be manufactured in great numbers but which nobody wanted was the Sinclair C5 for example, and thus it appears that whilst a bathtub makes in many ways the ideal receptacle for a piloted vehicle (bearing on mind the original cockpit was something of a cock-pit too), few if any people want to be seen driving one down the High Street.
Design of electrical vehicles that fly is thus a balance between the possible and the desirable, and the current response to this at the start of 2022 is for any number of companies to produce CGI renders of what look like flying Lamborghinis in an effort to persuade gullible VCs to part with their cash, which is altogether easier than you think if you look the part… Therano shares, anyone, or would you prefer One Coin instead?
Back in the real world however and with the Challenge in sight, there was a more or less panic-stricken search for alternatives that would literally fit the bill on our part if it did not mean simply turning up with an over-sized scale model of what we proposed. It was at this stage therefore that I realised that whereas the four-pronged outline that I had developed (using aluminium section, alloy sheet and core foam) was sufficiently rigid to include a hole in the middle into which I might fit, as per a pair of trousers. At the risk of it sounding like a contraption out of Wallace and Gromit, this had much to commend it.
First and foremost, it obviated the need for those pesky and expensive flight-controllers and the associated wiring and electrical components that went with them, not least the radio-control box, transmitter and receiver necessary for remotely-piloted test-flights. Secondly, and not least, it had actually been done by a university team in India as a trawl of YouTube had shown. It was not nearly so slick a design as our own, with fairly sizeable dimensions and based upon a regular tic-tac-toe configuration of octocopter that had become more or less standard worldwide, but it had the distinct advantage of clearly working, for at least once.
The question arose of course in the absence of computerised control means as to how to steer this mock-up-without-the-phone-box, although this was to have been by weight-shift alone. Weight-shift is the poor relation of aviation, although it has been used in every manner of successful types, among them gliders, gyrocopters, helicopters and microlights. In other words, anything sufficiently compact for the shifting weight of its occupant to affect its flight trajectory in the intended direction. At the outset many designs of aeroplanes had however to be decidedly large to generate the required lift at the low speed available given the equally low power available from the power source. In fact the Wright Brothers (and the French) pioneered the sort of aerodynamic controls that go beyond mere weight-shift that remain in use today at every scale through to the Airbus A380.
If however you look at experimental personal helicopters on the same YouTube you will see that the majority involve merely tilting a rotor-disk in the required direction of flight, and given that the single most populous type of aircraft worldwide in the form of the paraglider or hang-glider retains the means of control, then it is not to be sniffed at. In fact it remains our initial entry in the prestigious Vertical Flight Society database of weird and wonderful global efforts toward an electrical means of take-off and landing; and despite it putting any number of investors off as if they were diners at a restaurant serving porridge mixed with snails, we’ll stick with it proudly for the record.
Three good reasons however militated against its development beyond the rudimentary mock-up stage. And a word here relating to mock-ups? The reason the bulk of projects out there pursue CGI renders in place of real flying machines is not only it being that much easier than using a cold or sweaty work-shop, but that you and I are of a generation impressed by shiny baubles over content, whether it applies to politics or all else. Nonetheless the bulk of flashy products that you use, whether supercars or Dyson appliances will likely have been modelled at full-size and as often as not in materials like clay in order to establish the look-and-feel prior to production. You and I however only get to see the glossy render or finished product, so that the bulk of my work looks shit to you, the way they thought Van Gogh’s sunflowers looked decidedly childish. That does not matter so much to me however as (a) how it flies and (b) how inexpensive I can make it without unduly compromising safety. (Actually I have to make an exception for the ongoing prototype ~ Mark V in aforesaid VFS database ~ that people appear wholly to approve of in every apect having seen it fly. Wholly disappointing really, given my track-record…).
Why not then a helicopter that you could pull on like a pair of trousers in order to fly to the shops instead of getting the car out?
Well there were three reasons, really. Firstly we had been provided with a pair of mentors by the GoFly organisers, which in my case were a retiree with an illustrious background in developing helicopters for the likes of Bell, beside a member of the US armed forces on the identical side of things. The former expressed his reservations as to what a decidedly ‘personal’ means of flight ~ and the inevitable landing ~ would have upon the lower limbs. Helicopters have through painful experience come to be designed to provide the maximum protection to seated passengers in the event they drop like a sack of potatoes, as they have so often in the past if only for the statistical likelihood.
Secondly, form my own point of view expressly personal means of flight like this never seem quite to have taken off figuratively beside literally. Having been in and around aviation for decades at every level, I knew that nobody quite wanted things like gyro-copters even if James Bond had briefly used one before re-entering the Aston Martin with a degree of relief. Nor had single-seat helicopters gained much traction, whereas two- and four-seater varieties littered the skies. And when powered parachutes emerged, they did not prompt a rush of pilots toward them, and in fact came to be viewed (quite rightly) by the public as a dangerous sport that killed people that you knew, like motorcycling or electric scooters.
Beyond this in recent times the ‘personal multicopter’ was the recipient of bad vibes from the aviation authorities, which like all human organisations are wholly obsequious to power and/or money but like nothing more than to bully the defenceless. (Please note that I am prepared to retract this statement and lick your boots as necessary, however.) As a consequence recently the guy who invented the stand-on platform of whirring propellers in Canada some years ago was lambasted for a take-off without permission from the air-traffic controllers involved, despite doing a demo at roof-top height several miles away from the air-traffic controllers they wanted to have been involved… or the aviation equivalent of needing an HGV licence in order to use an e-scooter on your driveway. Possible then that such means of flight will remain ever the novelty?
The final nail in the coffin however came from the organiser of the competition itself, whom we met in the Savoy Hotel in London whilst here to give a presentation at the bi-annual aviation convention nearby known as the Farnborough Air Show. Gwen perused our radical airframe of the that sort of extended the powers of human-beings to flight itself like those of Superman, and said “You’re not bringing that.” In so far as the public were concerned, it seemed, there was no escaping the fact that I’d invented the human salami-slicer.
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| It's a helicopter, Jim, but not as we know it |
