The Ugly Duckling

And this is what I mean... maybe doesn't look the part but it's eminently doable whilst safer than a quad and more efficient than an X-8.

An ugly duckling though which I'm sure would prove to be a beautiful swan in flight?

Draft Excluder

The second of a thousand steps, and what I use to exclude (or include) options at the outset is a rough outline that I draft in Apple's Pages app. I worked in computers when PageMaker was introduced, and was subsequently rendered obsolete ~ as were WANG Word Processors ~ by the improved functionality of programs like Pages and Word.

I have been known to sketch these outlines on the workshop floor (as indeed they did in chalk at the time the Titanic was built) but this is quicker, less messy and equally enjoyable.

Here we can see straight away that the eight-ball layout is not as attractive as might first appear, bearing in mind that each pair of propellers rotates the same way. There is no problem with this if the cantilevers are extended to 18" around the 14" centre-section.

Left as close as they can be to the centre-section as in the lower half of the diagram, however, then diagonally adjacent propellers rotate efflux in the same direction; which is decidedly inefficient. Note incidentally that from the top each pair of propellers has to rotate clock-, anti- clock- and anti-clockwise in conventional quadcopter practise.

Benefits of the layout are a compact foot-print along with a concentrated entrainment of downdraught that adds to efficiency in the hover... whilst disadvantages include the fact the spars do not lie in the same plane unless separate cantilevers are attached to four-way connectors at each corner of the central square: which at any scale adds the the cost of specialised product that might otherwise not be necessary.

The choice as often as not in designing eVTOLs lies in that between 'geeks' and 'jocks'. One of these might not look the part but passes aerodynamics with distinction, whilst the other goofs the exams but eminently looks the part.

What we choose going forward is thus divided between two goals viz. do we want the most economical means possible to get airborne, albeit at an acceptable level of risk given a single component failure? Or do we want to design a commercial product a la Blackfly's Opener or Jetson's One from the get-go...

...that comes neither cheap nor quickly?

The Sermon on the Motor Mounts

Why do we do this?

Well I've lived a long time and seen computers develop from kit-builds that frequently failed and needed tending by high priests of the "computer room" of whose fraternity (and it was almost invariably male in those days) I was briefly and ineptly a member.

But now we barely give the equipment a second thought, devoting ourselves instead to what it can do.

In the realm of aviation, single-seat aircraft have always led a troubled existence and in the way that advancing nations like China evolve from bicycles toward electrical EVs weighing two or more tons in an effort to move individuals from A to B, so advantages of eVTOL will evolve toward where the money is most likely to follow: which is it, but with wings.

Nonetheless the most numerically successful motorised form of transport of all time has been the modest Honda Cub, which was specifically designed for noodle delivery in the narrow back-streets of Tokyo and conquered the world from there. The earliest form of transport common to all civilisations too was likely to have been the litter or sedan chair, which was basically a box-seat with a human porter at either end prior (a) roads and (b) wheels.

Most of the best work I've done on advancing the art of eVTOL has been lying awake at three in the morning, at which time the outline see here was sketched out. French exercise books incidentally are squared and ours in the UK are lined, which is likely the reason they build Airbuses there and not here.

For really it's a time to return to our roots, and build something we set out to do in the first place, which was exactly that: a flying box-seat with an octocopter on top.

It has really to be an octocopter for resilience, but from the outset this was one with a difference because uniquely it was a pair of quads stacked one atop the other with overlapping propellers which co- instead of contra-rotate: a type of 'virtual quad' safer and more efficient that plain-vanilla four-motored multicopters.

You can read about it more here: https://www.tdcommons.org/dpubs_series/6778/ but don't take my word for it and let physics do the talking instead.

Fact is though, some four years down the line and with all of the experience that we gained building and flight-testing a half-dozen different configurations at half- or full-scale... it would be altogether easier this time around.

The picture below shows the rig that was first fitted and successfully flown with an underslung box-seat that would accommodate an adult, albeit uninhabited. The only reason in retrospect that it was ever reduced to a quad was because of the logistical challenges connected with checking it for flights between London and San Fransisco in order to attend ~ and we were the only UK team that did ~ the competition there.

Like computers, this stuff will one day be taken for granted for all inventions ~ as the philosopher Schopenhauer observed ~ are eventually viewed as self-evident by us all.

Further Notice

Picking up where we left off, what have we learned over the past six-something years?

Let's take the long view, as ever. In the week's news, songwriters' fears over their roles being substituted by AI. In Huxley's eponymous Brave New World, posited over ninety-five years ago, the songs were composed by computer... takes longer than you'd think.

We've successfully flown now with both four and eight props in the overhead and with four beneath the feet. We've also flown most recently with four in the overhead along with four around the feet. What the latter proved however was that the frame needed to be decidedly rigid in order for the flight-control computer to address the motors at each corner of a virtual cube.

That meant more both more weight, more expense and (quite literally) less flexibility.

Meantimes the eVTOL world has evolved into multi-seat multicopters at the scale of 'flying taxis' and a plethora of personal air vehicles of all shapes and sizes, although generally featuring reclining accommodation as per either the Blackfly or Jetson types that are (perhaps not coincidentally) nearest production.

Accordingly if an upright vehicle is to quite literally stand out from the crowd, then it has to be the most compact on the street and so far as TELEDRONE is concerned, not least because of the budget, that means we need to lose the phone-box.

As a consequence let's turn to a notion which arose in the workshop mid-pandemic, and which I've released publicly at https://www.tdcommons.org/dpubs_series/6751 and whose principal benefit as that it is field-deployable in portable parts. We've looked at any number of propeller layouts along the way ~ each having pros and cons ~ but for our 2024 build I'll use the most compact I've yet devised.

Again it is able to support either four or eight motors but either way it was revealed to  an adoring public just last year in the shape of UK registered design #6256068.

I hope you like it.

UAM, UFN...

This blog is suspended until further notice.

Photo Realism?

Around the middle of January I was notified by Google to the effect that the business profile had been amended from Aircraft Manufacturer ~ which admittedly was a long shot ~ to Photographic Services. There is one thing to note at the outset about your Google business profile, in that it cannot be deleted. The second thing to note is that what your business does, is not your choice but theirs... or rather, their bots' choice.

For unless someone registers a complaint against a business profile, then Google will alter it themselves if they consider that doing so is warranted. Quite how they came up with Photographic Services though eluded me. Was it those beautifully crafted shots in the studio, or was it simply drones being more readily associated with aerial photography nowadays?

For the fact is, the only Google business classification attaching to drones as such is 'Drone Shop' whilst the burgeoning field of eVTOLs warrants no classification at all as yet. Truth is though that TELEDRONE was only ever incorporated in order to satisfy the rules attaching the GoFly Challenge back in 2018, such that its organisers retained a shareholding.

There is something Orwellian about Google's AI defining who we are and what we do, though when all is said and done I draw comfort from the fact that the best advanced eVTOL 'manufacturer' on the planet (in the shape of Joby) is better known for...

...photographic equipment.

State of the Dro... nation Address '24

So this is where we stand going forward into '24... the outline I like, it being the most practical compromise from every point of view. Nonetheless the most recent flight-tests have illustrated that in order for it to fly successfully as an X-8 configuration the airframe has to have sufficient rigidity between upper and lower quads. This costs a good deal if it is to involve the use of aviation grade alloys or else carbon-fibre at each turn of design and manufacture.

At the same time, to benefit from the single-failure redundancy that X-8 configuration affords commercial drones, a power-to-weight ratio of almost 3:1 is required; or so I'm told by people wiring, tuning and flying these things. That's also prohibitively costly to implement in terms of the required equipment and not least, in terms of the outlay on the certification that it would require in Europe and the UK, where Part 103 does not apply. It is altogether disingenuous to take advance deposits on personal air vehicles for use in regions where they are illegal to operate, but this does not dissuade most of them from doing so whilst public and investors remain ignorant of the fact.

There is thus a cogent argument to scale up by way of baby-steps and re-design the same outline for operation within ground-effect. It requires certification neither here nor there, serves as a developmental step in the right direction and proof-of-concept, whilst at the same time reducing the cost of development considerably.

This is not least because ~ as I've said all along ~ it makes eminent sense for a lower quad to be optimised for thrust and an upper for direction. The bulk of energy is used by eVTOLs in the hover by the cycling of RPM in order to preserve stability, a fact that could be capitalised upon by a larger set of motors and propellers around the base of the airframe being limited to constant operation at a higher RPM.

Thus if we are going to enlarge the scale to adult-size then it's as good an opportunity as any to reconfigure both the machine and me for flight around ground-level. We live for better or for worse in a world increasingly subject to fire and floods, both of which offer obstacles to conventional means of mobility in extremis.

Shoulders to the wheel, anyone?