Silence of the Laminates #2

Here's the raw material, from a single sheet of which I made a a deck, a keel and a pair of outriggers for stability during powered testing. If you look carefully you will see that it reads XPS Insulation NoMorePly 20mm 1200x600x20, doesn't it children?

Turning to our textbook we remind ourselves XPS stands for extruded poly-styrene. It is basically one up from the shitty stuff they use in bean-bags, and still too soft to drive a screw into; although you may have used a bean-bag to assist such purposes in your youth.

Accordingly although we need no more ply, as it says on the tin, we do need means with which to attach the spars. Here these have gone back to a lateral variety unlike the longitudinal spars that proved better on the 3rd prototype, incidentally.

Tune in to the next post now to see how this is best done...

Silence of the Laminates #1

It's a holiday weekend here in the UK, so why not settle the kids down in front of a screen and get back to building maritime drones? I've a fourth prototype on the go in the shape of a 'flying test-bed' of the sort they built before Harriers took shape.

It has sat in the corner of the workshop for weeks, even though Patrick Swayze said it shouldn't have. Originally an experiment to see if we could go down the laminate route, it proved that so long as a cruciform construction like this was used, the keel would be every bit as robust as the cantilevered types that preceded it.

I've put a pencil-sharpener for scale ~ bear in mind it's used on a two-metre pencil.

Go In, Stay In, Tune Out

Preparations for war to date in the UK consist majorly on the PM having mentioned in passing that it's coming to a street near you, and a .gov page on what to do in case of being irradiated. The West now operates a 'rule by slogan' form of administration in which catchy soundbites like 'smash the smuggling gangs' substitute for actions of any sort.

Meantime in Lithuania ~ where I spent much time relating to flying training ~ they are establishing centres where 15,000 adults and 7,000 children are to be schooled in the basics of designing, building, programming and operating drones.

Nothing new, though, the Russians having long organised video gaming conventions for youth, from which participants are cherry-picked for less innocent pursuits.

Have a nice day.

Delta Force

Great thing about the 'net is that it's Darwinian evolution on steroids: people ask to be video'd say, walking around a cliff-face hundreds of feet up and whoops, they're gone.

Likewise these shorts are titled 'Is this safe' and... if you have to ask the question?

They do though demonstrate the aerodynamic stability of delta planforms, which is admittedly not what the average viewer is thinking. Put any form of multihull in that situation, for example, and it's a back-flip you're watching instead: triangular wings simply 'mush' where squarer ones might stall or somersault.

If ever the drone gets on the water, the proof of the watery pudding will be stability in and around situations like these. Whichever way you look at it, however, critical dynamics of hydrofoil and aerofoil surfaces will be much more to the fore as vessels get smaller, lighter, faster and uncrewed.

Both of these videos required constant manipulation of the controls by each jackass, though a computer would make light work of stabilising such angles of attack: as it does with fourth and fifth generation fighter jets.

What Goes Round (and Round)...

It occurs that one day we might sit ~ or stand ~ on a version of our boat, although I'll likely still be imagining it on my death bed:

Colin: We're there, aren't we? On the beach in California?

Priest: We are! The sun's setting. There's a crowd... they're all here for you.

Colin: And they're singing?

Priest: They are... the birds too.

Colin: Lift me up! Set me on the seat!!

Priest: You're on the boat now... the propellers are humming!

Colin: The counter-rotator's?

Priest: The counter-rotators.

Colin: Aaaaaaah.

Priest: I'm done here nurse ~ just one more nut-job at the end of the hall.

Let us examine what is out there however in terms of PAVs or personal air vehicles as opposed to PWC, Personal Water Craft (or Price Waterhouse Cooper).

The Volonaut at top-left will leave you with little change from a million dollars, but is from the same people (person, practically) who brought you the Jetson. It doesn't fly for long, sets fires we could do without and is not new: the Williams X-Jet below appeared in 1974 although you had to tilt it to steer. Nonetheless both are perfect for pissing off (or on) the neighbours.

Alongside, the Skysurfer also comes from a talented and passionate engineer (and I'm neither); but he doesn't quote a price, which is the last thing you want either online or in a brothel. It also has expensive replacement propellers written all over it, but hey, it's out there.

Below it however if it was propellers you wanted then Hiller's flying platform served a purpose back in '55. It was not nearly so practical as the altogether simpler (and safer) gyrocopter, however, and was never going to be parked on your driveway: which is where tech comes into its own as regards universal accessibility.

There's clearly a case for eVTOL taxis flying sightseers and rich people around, but motive means for individuals (there are no single-seat automobiles that I can see) except those on two wheels have a chequered past that I don't see improving any time soon.

But we keep trying, as the flowers bloom each Spring.*

*To paraphrase Herman Hesse, who so far as I know never owned an eVTOL.

X-Plane

Kate Bush has been calling again saying, Don't give up, 'cause you have friends! Don't give up, you're not beaten yet! Don't give up, I know you can make counter-rotating propellers work!

Accordingly I have looked again, and settled upon this as a solution: one motor fixed to the rear of the deck and another that can be popped into place and removed if ever the propeller in the background should need replacing.

A rule related to building drones that I've just made up relates to (a) how easily carbon-fibre propellers are damaged and (b) how often they need replacing. This arrangement addresses both issues by proving the necessary protection from damage, whilst still sticking to our 'plug and play' philosophy. Furthermore it still allows the drone to be stored (or dried out) upright.

And whereas the previous arrangement looked a bit of a dog, as our CEO put it, this one looks both purposeful and practical.

I've a recent mail from a hobbyist, saying he too knows when a drive-train just fits if he 'thinks of it constantly and buys it flowers'.

I've removed the email address now.

Counter Argument

Counter-rotating props rigged at the back-end ~ counter as without a common axle. By extending the stripwood and ski it still stands on end, but looks and feels messy to my mind.

I'll hang it ~ or myself ~ from the rafters and look again at one motor and propeller at the leading edge, reserving the space here for a rudder.

We'll bank this idea for now, although it holds out the prospect of rolling the craft into turns using differential thrust alone.

Rudderless, in fact, as the project itself feels much of the time.

N.B. Anyone spot how both propellers are set to run in the same direction? If you did, get a life.