Thursday, April 9, 2020

Covidiary #6

I register the above as a design, and I might as well flaunt it for a few days while things are quiet build-wise, not least because everything in the way of tooling and materials has to be ordered online in view of the national Coronaviral lockdown.

From hereon in it has to serve as something of a talisman and the basis of all flight-testing going forward. I debated the colour, having initially (as can be seen from the 2/3rd scale proof-of-concept below) gone for matt black for elements below the phone-box. 

I did this because the original K8 phone kiosk on which it was loosely based stood upon a black cast-iron base. Nobody would ever notice the fact however unless it was pointed out to them, and thus it seems pointless to use it here.

Beside that, the interaction with junior members of the public at the NASA Ames event at the end of February showed that the superstructure of the undercarriage is invariably a trip hazard, and thus ideally rendered as conspicuous as possible.

Apologies for a lack of posts over the past few days, while I took a break in the fine weather to do the back garden. Churchill did the same at times of national crisis as a diversion (and he an accomplished bricklayer), and I don't see why I shouldn't...

Friday, April 3, 2020

Covidiary #5... Saved by the Bell-47

After much head-scratching and ceiling-staring yesternight, I see clearly how these lower propellers are to be physically protected and skids fitted, and I do so by swinging the lower quad through ninety-degrees. This provides a suitable mount for the sort of skids sported by the original 'MASH' Bell-47s, a helicopter that for many of us was our 'first love'...

Thursday, April 2, 2020

Covidiary #4

Struggle for much of the day with my diminishing supplies of alloy and a pop-riveter that needs replacing inside the week. I construct and re-construct a couple of variations on the configuration of the two drones around the frame, seemingly unable to pitch the lower set of props where I want them without either adequate protection for either their blades or else the passenger. During the evening though I've a eureka moment: shall add a wholly separate undercarriage module that supports a pair of skids that underpin the lower set of motors and the longitudinal extent of their blades. Have already decided that one way or another for the take-off and landing phase these propellers can be stowed so as to benefit from this form of protection...

Wednesday, April 1, 2020

Covidiary #3

This is truly hopeless.

I consider any number of alternatives by way of suspension and undercarriage, which costs me not a little on eBay and Amazon, to little effect. I believe Edison trialed over 600 forms of filament before landing upon tungsten ~ or its equivalent back then ~ and this is the tragedy of reverse engineering... the product that is eventually copied represents the tip of an iceberg of both spending and effort.

As a consequence I ditch the idea of sprung undercarriage altogether, except for the inherent elasticity included in whichever structure I settle upon. This was a path worn by Volocopter, whose original prototype landed upon a gym ball set at its centre before ditching this in the institutionally-funded prototype that sports a conventional set of skids.

What I resolve upon instead is using the self-same module that forms the upper and lower drones to form the basis of a separate undercarriage fixed to the base. As a consequence I need to relocate the lower drone and to do so I shall remove the centre-body and slide it up the 'phone-booth' so as to support it like a traditional litter, or sedan chair. While I am at it therefore I might as well do the same with the upper quad.

It is something I did consider at the outset of re-designing the airframe subsequent to visiting California, although I abandoned it for a more modular design with separate units viz. pair of drones and passenger compartment that can be disassembled. The route I am taking now really calls for a prototype that remains fully assembled, which in turn will mean it has to be transported intact and that will likely involve a trailer.

The benefit is that the structural space-frame is simplified and is therefore both lighter and stronger, which are perennial requirements in aviation. The art of design is ever one of compromise, like life itself.

Sadly I snap both of my remaining 4 mm drill bits in short order, with no replacements to hand any more now that retail outlets beyond food are invariably locked down, and the mail is patchy. I'm having to substitute for the lack of bolts by using the threaded rods that I have left along with nuts that fit. In other words I am practically having to fabricate my own bolts.

Sobering how much we depend upon each other for all else except sitting around to worship our various gods. And even that depended as often as not upon taxes and charitable giving.

Nonetheless after a cup of tea and an Eccles cake and a moment of self-doubt, I've a solution. Realise am trying to run before I can walk. Shall therefore configure the uppermost module with the quadcopter and the lowermost with a set of skids, simple as. This 'lunar-lander' will be equipped with feet in the shape of ~ literally ~ frisbees. And happily they come in black, the sort they'd be using on the beach in an Ingmar Bergman film. And beside all this I've finally got visualisations of the thing without endless iterations  in the workshop, courtesy of my cousin (airline captain and one-time architect). Things are looking up...

Tuesday, March 31, 2020

Covidiary #2

Might seem trite with practically four hundred souls succumbing to the fever in the past twenty-four hours to be building drones, but then when all of this is over and there's an almighty tax bill to be paid then we're going to need to earn the revenue. And so I plod on, inspired by the example of so many others in these direst of straits.

I'm taking it easy on myself as the song says during this lockdown in the UK, and I've limited myself to (a) changing the colour of the lower quad from black to red and (b) fitting motors to it. I like the expression 'lower quad' incidentally... has a distinctly collegiate feel to it.

My design philosophy centres on DIY, or literally the ability to do everything by yourself, and this extends to transporting, assembling, operating and disassembling where required. Accordingly as things stand what you have here is a simple quad some 50" square that is bolted to the bottom of a passenger compartment, with another bolted on top.

You're probably thinking that the lowermost set of propellers are going to be mowing the lawn, but I've thought of that. With what remains of the week there will be an undercarriage added, and like so much else that is a part of this design, it will be unique in appearance... I've always preferred the road less travelled.

One lesson from watching preparations for the GoFly challenge in fact was that the lightest possible airframe needs combining with the sturdiest possible set of skids, having seen any number of heavy landings. As things stand, helicopters (albeit with seven or eight decades of development behind them) have what I would call perfect 'poise', whereas drones do not. They hold there station with the consummate ease of a hoverfly, but land like a dead duck.

(On the software side of things too, the lower set of motors and propellers will be stopped prior to landing, in order to give those expensive carbon-fibre blades a fighting chance).

Monday, March 30, 2020

Covidiary #1

Eleven o'clock this Monday morning must have been ground zero in terms of my motivation. With stores either closed or closing and deliveries re-prioritised in the face of the pandemic, it is hard to know quite how to proceed.

In the first instance I shall make-do-and-mend in terms of the material to hand in order to complete at least a static exhibit to list on the VFS database;

In the second instance I have as of today effectively frozen the design for the foreseeable future, so that by hook or by crook it will have to be made to work... and no 'ifs' or 'buts'.

In the third, there has to be a fundamental re-think of how best to proceed in the face of adversity, in the way that nations re-configure daily life during war-time.

I do have an idea that combines all three, but more on that later.