Tuesday, May 7, 2019

Technical Disclosure 08-MAY-19

Largely (as with the disclosure of 06-May-2019) for the record.

The target remains a wearable quadcopter that ideally can be steered by weight-shift ~ this being the simplest possible implementation of the various parts of the assembly.

Nonetheless these two outlines provide a means of supporting the weight of the airframe and batteries on the ground, and of the operator in flight in lieu of a crotch-strap.

Note that in either case the integrity of the 'drone' is preserved, its aperture still slipped around the waist and its bulk supported by shoulder-straps to leave the operator free to perambulate.

Difference is in this event said operator can step into the above frame (not unlike a Zimmer) and attach the flying section to this ground section prior to take-off... having connected the (greater) volume of batteries supported by the latter.

With the disclosure of two days ago, ditto excepting that the operator first dons the quadcopter and is afterward seated on the chair prior to attaching both it and the batteries supported beneath its seat.

Going forward then and given the current state of the art as regards electrical storage I envisage a short-duration flight wearing the drone itself and a limited battery-pack in the form of webbing, whilst the stand-up frame above allows for more batteries and a longer flight duration.

Finally the chair provides the greatest bulk for electrical storage and the longest flights.

There is of course a trade-off in so far as the frames themselves (at least in alloy instead of carbon fibre) might four or five kilos of extra weight, as do the larger batteries themselves.

Nonetheless this is a trade-off (fuel versus payload) that has existed since the dawn of flight.

Rudolf the Reined-In

Realise that according to the contemporary commercial ethos grand developments are supposed to sacrifice the family to the greater good of progress, but at my age there's a different perspective and it being a holiday weekend there's a museum for us to visit.

The Commercial Vehicle Museum is situated in Leyland, in the county of Lancashire here in the UK. It was not just historically bound up with aircraft manufacture but with that of omnibuses, steam wagons and later diesel-powered lorries (or trucks).

In fact at some time, given it was grist to their mill, they acquired Rudolf Diesel's original prototype. It looks big, but current marine Diesel engines are altogether bigger. This unit, given its preponderance in moving the world's goods around on land and sea, has probably advanced the cause of globalism more than either war or words.

It was from a vessel on the English Channel that Diesel disappeared, never to be seen again.

He was thought to have suffered the same fate as the inventor of nylon (suicide), but there is a good deal of support nowadays for the suggestion that he might have been the victim of a nascent 'big oil' lobby. Reason simple: his engine could run on practically any combustible fluid and at the time he was supposed to have been promoting the use of vegetable oil. Or peanut oil, if memory serves.

I recall the earliest venture toward resurrecting EVs in California in the 1980s, which was comprehensively trashed by big oil. And fans of Netflix documentaries will know that anyone making any plausible attempt to derive energy from plain water in lieu of oil turns out to have been 'lost' or indirectly threatened in similar circumstances in both the UK and US.

The only way around this is (a) to make lots of money and (b) make a noise and therefore despite its best efforts, the same lobby has been unable to make much of an impact on the sainted Elon, who may come to be viewed as having done for electrical road and air vehicles what Diesel did for those on roads and sea.

Monday, May 6, 2019

Technical Disclosure 06-MAY-19

In designing eVTOLs we're about where they were when personal computers or gaming consoles were invented i.e. aggregating disparate parts and in our case to source, distribute and govern electrical power.

It is clear too that batteries are something of a moving target currently and that a broad brush is required for drafting electrical flying machines.

I have every confidence that a wearable eVTOL will in the fulness of time be useable with wearable power-packs, but for the time being we also need a fall-back.

This then an outline for a part to support both operator and batteries.

I'll mock it up in wood to my satisfaction and for your delectation.

Thursday, May 2, 2019

Game of Drones

Been practically a month since I signed in but as ever, no project is as simple as it appears at the outset. As one of the webinistas put it: VTOL is hard. Specifically I've been grappling with the electrical side and it is becoming clear that batteries are the key.

These things used to be staid: I was brought up on cells like those pictured, the sort of brand that you suddenly ask yourself where ~ like Kodak ~ they disappeared to? Their background is similar... whilst Kodak stuck with silver for producing images, the UK's Ever Ready  company stuck with zinc for producing electricity.

They were eclipsed by Duracell's alkaline batteries, which promised altogether better performance. Ironically in the way Kodak had developed the digital camera and left it shelved, Ever Ready did the same with the alkaline cells they'd developed in the laboratory.

Much the same regime change is underway now, but at a vastly accelerated pace and with a step-change in energy content. Problem for developers is that the selection is bewildering and ~ like the nascent personal computer industry ~ batteries are loosely 'packaged' like the earliest computers that emerged from Silicon Valley. Accordingly, Tesla and Nissan are already on their second generation already.

Given all of this, after 'stepping away from the vehicle' for a period of reflection, I have an alteration to the prototype that involves packaging the batteries in a decidedly conservative way... the trick at this stage is, I feel, not to be too clever.

Watch this space.

Monday, April 8, 2019

Work to Rule

Pleased with the days work... the 18-inch frame seen fitted here with 36-inch propellers, ample rule for a bit of armour around my bod and that's 8 feet 5 inches across the tips (or an inch inside the GoFly guidelines).

I actually still like the props mounted up top too, not so much because the motors need the cooling (but then every little helps when you hit TOGA thrust) but because you can scope the tips altogether more easily.

An advantage of eVTOLs over helis is the fact you can get up close and personal, and I figure with white tips and LEDs you can place those propellers within a smidgeon of obstacles.

A (Navigation) Bridge Too Far

The 12 x 14-in deck at right proves a 'bridge too far' when it comes to ergonomics, hence:

(a) 18-in (ply) version an ideal balance between protection, weight and propeller-clearance.

(b)  square outline better than rectangular (which required two spars to be foreshortened).

(c) the operator's cut-out is better set back to provide adequate margin for manual controls.

The latter will pitch the C of G rearwards and to compensate I shall ballast with fixed battery-packs plus a swing-seat that will pitch the operator's legs forward and hopefully centre the trim for the cruise.

The picture shows the 18-in ply outline overlaying the 20-in alloy version ~ which must now be modified to suit ~ while the smallest embodiment appears at right minus its rotor-arms.

The dummy propeller parked at the end of one of the (39-in) rotor-arms measures 36-in to suit the one selected for the prototype.

The cut-out is enlarged to 14-in wide and 10-in deep, hopefully providing investors a chance to squeeze in themselves in order to get the 'look and feel'.

I've sat in myriad cockpits during a long life, and frankly this one's up there with them if only for its novelty.

Friday, April 5, 2019

Cogito Ergo Nomics

There are times during development when you're at a crossroads, and having reduced the chassis yesterday to just twelve inches by sixteen, I am decidedly unsure about which way to proceed.

I could stand on the same outline holding on to a form of Zimmer frame, but although this is a common approach to eVTOL I don't think it's the optimum. From a general point of view it is the very least stable in aerodynamic terms and wholly reliant on either a very acute sense of balance or else computer stabilisation.

An airline instructor told me once how a colleague found himself flying an F-16 without the necessary flight control computers. Bearing in mind such aircraft are inherently unstable to improve manoeuvrability, he was delighted to have been able to control it for as long as he did prior to ejecting.

I also consider the layout at foot-level augmented by another at waist-height to compensate; or even wearing it like a yoke with a crash-helmet protruding and hands hanging from holds.

None of it feels nearly as comfortable as hanging the thing around my midriff ~ a location with the benefit that the centres of lift and thrust would appear to be ideally aligned.

In the event reducing the foot-print proves to be a net gain with two lessons learned:

(a) motors and propellers do need to be mounted on the underside so as to free up my arms

(b) the spars themselves prove an ideal mount for the manual flight-controls

In other words the left-most spar is ideally placed to support a side-stick whilst that at ninety degrees to it can be used to mount a thrust-lever (or collective, to the rotor-heads among us). I find that the former works about 45cm forward of the rear spar and the latter at around 35cm, incidentally.

You can of course simply invert the chassis in order to reverse this arrangement, particularly in view of the fact that helicopters are steered with the right hand.

Nonetheless I have only ever flown an Airbus as commander and it therefore would feel only natural to me to guide the vehicle with my left hand ~ indeed any Airbus captain will tell you that adapting to a side-stick at all, and in the 'wrong' hand too, was easier than anticipated.

The photo is a montage because I'd lost the selfie-stick. And ignore the beer-gut if you would, please?