Monday, May 18, 2020

My Work Here is Done


I re-abandon the idea of testing the prototype in the absence of the phone-box, and by the end of last week had effectively gone as far as I felt inclined. Without mentioning the Titanic I would compare this stage to that prior to 'fitting out' as it applied to shipbuilding... the moment the hull is launched (or wheeled from the hangar in my case) ready for its luxury superstructure to be applied.

This will take the form here of wiring up the electronic components and programming the associated parameters for flight. As per the launch of a ship, what you see here is equipped with the equivalent of the coal-bunkers and steam-engines, except in the form here of Lipo battery-packs and electric-motors.

I would have liked a pack to address each of the eight motors, but the fact we'd already invested in a pair of seven-cell packs suggested it were better to invest in a further pair to suit the top-end of the vehicle. As the prototype is over-powered in its current form ~ flying only a Mothercare mannekin in lieu of a human being ~ a pair of six-packs would prove to be sufficient.

Despite the lockdown I managed to source these off-the-shelf at Alien Power Systems, a company recommended me by Pete Bitar in the 'States and which proved serendipitously to be only a half-hour drive in the car to collect. Alien is my sort of enterprise, begun a man who arrived from Italy and worked in a restaurant prior to founding a successful operation that does business world-wide.

I also speak to the man who established DJI in the USA (a marriage made in heaven). He advises that with many hundreds of eVTOL efforts abounding on YouTube that it's no longer enough to get some sort of proof-of-concept airborne, but rather to prove that for whatever reason it is proven to be superior flight solution.

I'm confident this is, but that would be like Edmund Hillary saying at base camp that he was confident of climbing Everest. He did so too, but there was much between 'here and there'.

Thursday, May 7, 2020

Flying Bedstead


I re-visit a previous notion (search 'jury rig' here) armed now with the knowledge derived in recent days regards how to put this thing together. The drones now feature brackets around the outside corners of the centre-body with which the passenger booth can be secured with an external set of tie-rods.

The nice thing about transferring the load to the outsides of the structure (as the engineer Peter Rice pioneered with iconic buildings like the Centre Pompidou in Paris or the Lloyds of London headquarters) is that it is flying-friendly and in many ways takes us back to the earliest development of bi-planes, when you'd 'kick a tire and twang a wire' prior to flight.

A by-product of this development so far as the drone is concerned is the the payload can be swapped out for what is effectively a 'spacer' that separates the two drones ready for wiring and subsequent flight-testing.

It therefore references Rolls Royce's own vertical-lift test-bed, with the exception being that the drone here is as yet uninhabited. This I can accede to fairly readily, the original "flying bedstead' having accounted for at least one Wing Commander during flight trials.

The prototype is thus ready for delivery and officially 'ex-Works' as of today, from whence it will be transported upon the roof of the Jimny to the project's electrical engineering facility.

Wednesday, May 6, 2020

Devil's in the Details


Working my way through fitting out each drone prior to incorporating the passenger booth. This includes a double skin on the centre body of each, as I notice a degree of bowing on the lower once loaded up... which is unsurprising as this is the lightest gauge of alloy tubing that I am using ~ I started out building these prototypes at the heaviest and working backwards before working in the opposite direction, if only in view of the budget.

I also add battery trays to the upper drone as I want a pack to address each pair of rotors left and right, although this will involve a considerable outlay on the additional packs of Lipo. I add brackets too at the point I figure is best to mount the electronic speed controllers (ESCs)  before realising they will have to be relocated... though there has been endless construction and deconstruction from the outset.

The reason for having to relocate said brackets is that I discover there is a sufficient length of lead to connect the lower ESCs to the flight controller mounted on the upper drone. In effect this means that the upper drone will be the 'brains' and the lower the 'brawn' that will work in tandem (occupying as it does a literal and figurative lower level in the workplace).

Monday, May 4, 2020

Re: dux


This taken on Saturday May 2nd, and so effectively April has seen the prototype redesigned and rebuilt from the ground up, and single-handedly. Considering this is less than two months since the previous iteration appeared at the event in California ~ and during a national lockdown that saw the UK population effectively curfew throughout most of the period ~ then I can be justifiably proud.

All the elements are now in place. I had built an identical frame to that of the drones purely to support the undercarriage (by placing it under the lower), but this weighed an extra six pounds and seemed like an unnecessary indulgence. In the event therefore I lengthened the cantilevers by six inches to support each castor. I had wanted them fixed directly beneath the lower set of motors, but this only complicated the assembly and disassembly of each of these components and I prefer to err on the side of simplicity. It doesn't look to bad, and in fact adds that much more protection to the lower set of propellers.

Plan is these will be arrested and lined up with the lower frame during take off and landing anyway, so as not to leave them exposed. We totalled a pair of these at said event, at a cost of the best part of three hundred pounds as I recall.

Tuesday, April 28, 2020

Keep Calm and Drone On


Last Thursday a new pandemic low so far as I was concerned. Thereafter I discover that my sheet-metal supplier had re-opened for business during the same week, and the same for my alloy extrusion wholesaler. First time I'd been beyond the garden gate and legally dubious, but live fast and die old, I say.

And joy of joys, this week Britain's favourite DIY store has reopened for a form of business. It's long been my own favourite hardware mega-store when it comes to prototyping and I am glad to contribute to their revival. It's looking like we're over the worst of it, which is no consolation if you've personally succumbed to the pandemic, but there comes a point to when the body politic has also to be sustained for the longer term.

Thursday, April 23, 2020

Jury Rig


There are countless dead-ends in development, and this is destined to be another. The plan being that if it could be got to fly, then the centre-body could readily be swapped out for the phone-box and mannekin ~ the reason in turn being that at this stage the two drones need to be hard-wired.

The eventual aim is to use two wholly independent drones top and bottom, with the payload sandwiched in between. In the near term though the upper drone will control the lower and this itself is possible because their is sufficient length in the wiring connecting the ESCs (or electronic speed controllers) for them to be commanded from a flight controller fixed above the upper drone. Meanwhile separate battery-packs would service the upper and lower set of motors so as to reduce the wiring loom.

In effect this could be though of as the brain up top, connected to the lower limbs by a form of nervous system... whereas in the long run we want something like a starling murmuration in which the lower drone works independently whilst in concert with the other.

After all that however I have formulated a better means of incorporating the phone-box with the two drones, and I shall therefore re-cycle the above in accordance with that plan. This is nothing new though, as the many iterations have been re-cycled endlessly as a way to evolve the most practical means possible of raising a body by electrical means.

Like Frankenstein's monster.

Saturday, April 18, 2020

Covi-drone


With lockdown in the UK scheduled for another two-and-a-half weeks at least, I am as bored with diarising the fact as I am with the government's lack of preparedness... the response to any crisis in the UK invariably being a rallying-cry to save property-owners in London, along with their bankers.

To suit reduced circumstances however I have down-sized the prototype with a view to flight testing, and the foot-print (discounting the propellers) is exactly your feet square. The box itself remains a foot-and-a-half square although it is reduced to two feet in height, as it may were it to accommodate someone of around four feet in height themselves, which is what I figure the mannekin to be without being able to take the measurement.

One decision I make today as that it is not, after all, worth flying the prototype 'as is' with just four motors up top, as we've done that already albeit under a different arrangement. It therefore behoves me to fit a pair of skids as per the registered design, and to get it wired up with all eight motors as illustrated i.e. with four up top and four down below.

Only this way ~ reflecting an apparently unique configuration in the world of drones ~ are we likely to prove anything much at all, and not least the notion that one day it might safely fly pilots from A to B.

This leaves me two propellers short, however, they being casualties of the trip to California.

But then Rome wasn't built in a day, was it?