Cogito Ergo... nomics

I take a better look at the mannekin and really he ~ though he may be transitioning ~ is more two-thirds scale than half, standing as he does at a metre tall.

Each of these centre-bodies are tho' built at half-scale from two by four feet backer-board: the one on the left designed for droning and requiring only three quarters off ~ it being broadly six-inches square and the other eight.

Experience from having flown scale-build octocopters would suggest that it will be a struggle to keep the weight down, and so what I intend is to construct two maritime drones using identical centre-sections like that on the left... and supported after all on 18" struts at each corner.

One of these is to be fitted with two cruise motors and dummy lift-motors to demo operations in displacement and on the plane as a regular cat; the other will feature four lift-motors and dummy cruise motors in order to demo unassisted launch from land onto water, and operations just above it at speed inside ground-effect.

The benefit of the latter is that it can be demo'ed equally over turf as over water: a whole lot easier in terms of recovery should it come to an unscheduled stop for any reason.

I've two sets of skis courtesy of Wickes home depot store ~ who have yet to realise that they sell skis  ~ and the plan is to finish the crewed mock-up prior switching a pair of skis over to the additional drone-sized version.

All in all I'm happy with how it is coming together. I like hovercraft and helicopters beside boats and the idea of combining all three in a way that is straightforward and largely free of regulation is as attractive to me as it must be to so many others.

So let's make, make a better drone, for you and for me and the entire human race.

Ed. I think I'm going to be sick.

Back to the Future #10

We've probably touched on this elsewhere but the box is unlikely to include perfect joins all round and so what I do here is switch to silicone to seal it up altogether. At the same time you can pop a bead of sealant down the outsides of the box where it about the cap-ends, principally for extra support (because they are anyway sealed from within).

Silicone preferred at this stage because (a) its cheaper (b) its lighter (c) its quicker and easier to apply. Nonetheless it produces powerful fumes in enclosed spaces and should at any stage you feel that you are being watched over by a giant rabbit then it is probably time to take a break.

Lift Plus

And here's what I mean... as China races ahead in both robotics and electric VTOL.

But this beast from Shanghai is what they mean by a 'lift plus cruise' configuration, and what we are considering among these pages for our flat-cat.

Its benefit is simplicity, needing no actuators to vector motors from the vertical to the horizontal that might potentially prove to be something of an Achilles Heel.

On the other hand what they've done with it looks altogether more complicated than what might be achieved with a conventional helicopter carrying a similar number of people, like Robinson's R88 below.

I was long ago offered an interview by Bristow Helicopters in the UK that I declined, and had I not done so it would have been a Robinson that I'd be using for my initial training.

It's one reason I suppose that if I am to build a boat, it has also to hover.

For regular readers too, note the cable-cutter.

Max Flex

The question of how tall the struts should be to match the re-jigged accommodation raises its ugly head, and so I return to the lab to find out (once I've donned hazmat gear in order not to introduce even a speck of dust into the environment).

Am switching from uPVC skirting boards to stripwood for this build, now that Wickes (as I told them) has become the go-to destination for maritime drone-building.

What I've done is park the trailer on the middle of this eight-foot lath, because that is about how much the rear lift-props and that accommodation are set to occupy.

With laser-calibrated hydraulic jacks (out of view here) I discovered that these bad boys are unwilling to flex beyond eighteen inches... worth knowing as I had settled on twenty-four inch uprights.

What I shall do ~ as we always want to work in divisors of stock timber at 96 inches or 2440mm ~ is to settle for 16 inches instead. Or in fact 400mm, as the laminated foam that we set out with was rounded down to 1200mm by 600mm.

We could bend the timber further ~ and permanently ~ like Scandies do with chairs, but that involves a steam-room I don't have. Besides, this is set to be delivered in flat-packed form, which doesn't really admit anything that is curved from the get-go.

I used to remove extraneous items from within the frame of each photo in order to clarify, but now I can't be bothered. If that upsets you, you can leave now and take your things with you.

Back to the Future #9

This being the value of a mock-up or visualisation (in the highest possible definition and three dimensions): I dismantle the bods of a couple of mono-ski builds in order to re-build a centre-body to more practical proportions. The template is now at the level of the rhesus monkey, putting it well within range of those emerging from UK schools everywhere:

Ed. or just a little beyond his own school-leaving grades of D, D and E. He did tho' make president of the Geographical Society, enabling him to stay in the warmth at lunch-time playing documentaries backwards through the projector.

Back to the Future #8

I invite Monty ~ Teledrone's chief test pilot ~ over for a 'look and feel' sesh now that the booms have been dropped roughly in place. And you can see now why the propellers are to be fixed fore and aft, well away from the whirling cookie-jars.

This is a suitable 'lift-plus-cruise' configuration of eVTOL and the more I look at it, the more I like it as against a vectoring pusher-propeller arrangement (which does however require only four power-units, as against the six required here).

It has the benefit ~ as do all distributed electrical power (DEP) types ~ of simplicity, for to raise it into ground-effect requires only adjustments to the thrust from the lift propellers while pushers at the rear 'do their thang'. With vectoring rear propellers you would be having to juggle the angle of vector besides the throttle in order to stabilise ground-effect flight, which has got problems written all over it.

Am also greatly encouraged by the guy recently featured here who is going for the quadcopter endurance record, and who discovered that any forward motion (or else headwind) does wonders for reducing the draw on the batteries.

The MO with the baby above is, therefore, to squeeze that collective lever to power up the lift motors so as to ease over sandbanks, ice or snow or indeed launch into flight within ground-effect (or surface-effect if you prefer) when sea conditions are at their calmest.

Boats flying above the water are (a) faster and cheaper than ones in the water and (b) altogether less complicated than aircraft designed for free-air operation.

So pleased with what I see though that I decide to have a fried breakfast.

The singular advantage of the vectoring type at this stage of the game is that we can get away with two-metre booms instead of the eight foot (2400mm) spars seen here. Most carbon-fibre tubes retail in either one-metre lengths, or more rarely two.

Autogyrations

Many remarkable people lead lives that go largely unrecorded, and in the UK that is largely true of Ken Wallis: a pioneer of what are called gyrocopters here, autogyros in the US. He never really got the aircraft off the ground in terms of manufacture, unlike Igor Benson who at least produced plans for a kit-built type that consistently sold (and still does) from the 1950s onward. Electrification, interestingly, sees this concept being revisited widely if only for its over-arching simplicity.

Ken Wallis himself flew nearly three dozen missions in Wellington bombers during WW2, but beside this built or raced cars, boats, motorcycles and aeroplanes when he was not promoting this enduring form of aircraft.

I've only really one thing in common with him ~ dandruff on the shoulders of giants as I am ~ and that is the fact that when confronted with fitting two engines in place of one, we both came up with the same solution viz. if you're mounting motors in a co-axial configuration it is easier to do so front-to-front than back-to-back.

Whilst on the subject of design too, the gyrocopter is an object lesson in why ~ as in my beloved flat-cat ~ centres of thrust are ideally aligned with those of gravity and drag. In many gyrocopters (autogyros) the thrust-line is higher than the latter and whilst it tends to push the nose down, it is prevented from doing so by lift from the rotor that pulls the nose up.

If the rotor fails in this task ~ due lack of airspeed or negative g-force ~ the engine wins out and drives the aircraft into a powered dive of the sort that has killed any number of pilots.

But don't let that put you off.

I recall seeing three aircraft crash with fatal results at flying shows, one involving a gyrocopter... all aircraft bite, which is why I do boats.