Saturday, June 19, 2021

All Square?

I delay fitting speed-controllers (ESCs) at this stage to make the airframe easier to work on. Besides, it's important that we set up another look-and-feel session with the test-pilot (who insists on Recaro when it comes to his seating arrangements).

Blade clearance is clearly tight, but then the seat will be elevated and the propellers shrouded to an extent later on to compensate. Worth knowing too that the airframe is slightly under-sized even at half-scale, a result of having been constructed by leftover parts in the workshop.

As a result the perimeter lengths that run around the square which defines the frame run to only .85 metre instead of 1.00 metre, meaning that the propeller axes would be pitched around three-inches further from the centre-section in both directions.

By way of a 'development program' this iteration will likely be programmed for flight in parallel with a rebuild at metre-size, meaning in turn that the electrical equipment can be transferred across with no change in operability.

That said, working now on this vanilla-flavoured quadcopter instead of the octocopter, there's four of everything left over... and enough to build prototype serial number #2.

Mounting Tension

When I first fitted these motors, the question would be quite how? Like most motors for drones, these are 'outrunners' with a canister that itself rotates in place of a rotor. 

Accordingly they include a static base with an array of bolt-holes, which in turn means that there has to be access from beneath for a screwdriver. Some motors include an adapter which pitches the motor-mounts beyond the diameter of the canister, where they can be accessed from either above or below.

As to being set the task originally, I used a simple transfer technique and painted the underside of the motor before applying it to a paper template ~ the way that as kids we made potato prints.

Manufacturers like Boeing need neither potatoes nor poster paint to attach engines, but what they have instead is CAD/CAM. In the absence of this I suggest you get into a word-processing program and draft a template to print off and apply to the brackets at each corner of the airframe. 

Mark with a centre-punch and break for tea prior to drilling, which needs be accurate.

Zen and the Art of Motor Maintenance

The Way of Drone is hard, a life of rigid austerity devoted ultimately to self-levitation.

Looking at my work to date, I realise I have seen something similar in a previous life as an airline captain, during a visit to a shrine in Tokyo in fact.

Accordingly I arrange a pause in proceedings while a Shinto priest recites incantations over the airframe amongst clouds of incense, so as to speed it on its course with every blessing.

As a part of the effort, I compose my own haiku for the occasion:

O drone
Climb Mount Fuji
But slowly, slowly!

(Adapted from the work of Kobayashi Issa, 1763-1828)

All of which stemmed from a moment of supreme enlightenment when I entered a trance-like state in pursuit of the best possible way of fixing the motors.

For in replacing the three-way tube connectors with four-way, I attained nirvana.

Friday, June 18, 2021

California Dream... on.

My mystery shopper in ~ well I can say it now ~ in San Diego has decided to run with his own design, albeit assisted by his local fabricator. As neither of them confess to knowing a thing about drones, the past several days I've devoted much time pointing them In the right direction...  a case of the blind leading the blind if ever there was one.

This was what they had proposed with a view to a machine steerable by weight-shift alone, and the crux of my arguments have been

(a)     don't be fooled by YouTube videos, as few people show the many crashes prior,

(b)    weight-shift machines have generally pitched the mass of motors at the base,

(c)    use more motors rather than fewer,

(d)    and ideally avoid the losses associated with contra-rotating props.

Crucially I suggested that the prototype as envisioned would almost certainly topple over on Day One, taking out several hundred dollars worth of carbon-fibre propeller with it in a best-case scenario.

I'd have gone out there to assist except for the fact travel between the UK and US is embargoed by the UK government's overly-cautious approach to the Covid pandemic.

My efforts over past weeks have thus been among its casualties, albeit one that few of us will mourn beside myself.

I don't regret extending hands of help across the virtual ocean, though it has been a monumental ~ some would say simply mental ~ distraction.

Coincidentally news came through that my pre-existing effort had been granted design registration in the UK, something I use as a matter of record as much as anything:

... although to my chagrin (and doubtless influenced by Monty the mannekin) they've classed it under 'Toys and Games' in order to rub salt into my gaping wounds.

I do feel though like someone who's had a wild fling, and returned to Earth suitably chastened.

And the prototype to which I return ~ unable in the circumstances to celebrate our design registration certificate together ~ still awaits me in the corner of the workshop.

"You bastard!" It shouts, "Off to fucking Pasadena with your fancy octocopter were you? Thought the California girls would melt your popsicle, did you?"

"San Diego, dear..."

"Don't San Diego me, you loser, and don't even think of touching me with that electric screw-driver!"


Wednesday, June 16, 2021

WDA Weigh-In

Proud of this one as it's made of used material throughout, including the three-way tube connectors retrieved from the wheelie-bin and set upon with an angle-grinder. Had angle-grinders been available in Arthurian times, would he still have been king?

It's looking like a credible flyer already, and Monty can't contain his excitement at the WDA (World Drone Association) weigh-in. He's looking like a mini Tyson Fury, another machine made here in Lancashire.

Without the benefit of the speed controllers and wiring loom, we're checking in at 19.8 kilos or 44 pounds. It includes batteries, motors and Monty himself (who accounts for around 20% of the all-up weight).

Initial reactions? Well I've given it the sprung dance-floor treatment and whilst it can support my own weight in 18-gauge tubing (except the skids, which are 1/16th inch) I would prefer it to be a little stiffer. That would be addressed by the anticipated gauge of alloy section, along with the steel-cored tube connectors. These would add weight, but likely mean that the four external steel braces could have been omitted.

The blade-clearance is a little tight, but that will be addressed by my secret-squirrel technique for mounting the motors. Meanwhile there may be an argument for lowering the mannekin's centre of gravity further.

This could be achieved either by providing for a foot-well in the centre-section at the cost of integrity or by tilting him backwards deck-chair-style at the cost of complexity.

FAQ Terence tweets from Tiverton to say, "Fucking rivets? You're a loser who wouldn't know one end of a welding-torch from another!"

ANS Terence mate, if it was good enough for the Titanic then it's good enough for me.

Tuesday, June 15, 2021

Put Out the Moon and Dismantle the Drone

Of the aspects of all this that kept me awake at night, undoubtably the motor-mounts and undercarriage have most often had me weeping gently into my pillow. At 04:00 today however I figure out a solution for the mounts, and as I've already solved the skids the design of the basic airframe is something of a done deal.

With this in view I dismantle the mock-up intending to re-use the parts, together with odds and sods knocking around the workshop, in a half-scale working model. Or not quite, as they're all close enough to the required size without being exact, but I'm not going to destroy the planet for an inch here and there.

I start then with a rebuild of the centre-section, although upped from the 12" square used in the mock-up to the 15" here that I had kicking around. The cantilevers you see here are those lengths that formed the sides of the mock-up's airframe, and these I have left at 24" as I couldn't be bothered getting the jig-saw out. Me at Airbus: "Office please Hilton and explain why one wing is longer than the other?"

I've also repurposed the 18-gauge aluminium tubing for this, though 1/16th would have been my tipple of choice.

Here's a tip though: to line this up in the absence of what professionals call a jig, take two of your cantilever arms and bolt then parallel as shown, using the remaining pair (as indicated by the mystery gloves) as a simple prop. Then BEFORE you rivet the two remaining arms in place, drill the 6mm holes required in order to bolt the abutments together in a material embrace.

All of this works, and only too well. Am unable to re-use the three-way plastic tube connectors used in the mock-up, because they're now stuck faster than Excalibur. Always use silicone instead of mastic, children, if you're going to dismantle the drone. Meanwhile below, in today's double-picture feature, we can see how the assembly is flipped over in order to mark up parts for drilling:

Monday, June 14, 2021

Happy Mondays

Let's do it ~ build the world's lightest and most versatile people-carrying quadcopter.

I've started by envisioning the half-scale proof-of-concept that will haul Monty's ass around the sky. And having started to sketch it out on A4, I quickly abandoned doing so for Apple's Pages. This includes many features of what used to be called 'desktop publishing' back in the day and here its most useful feature is the ability to dimension the parts fairly quickly.

Pages accepts inches as an overwrite for centimetres and thus we can go for an A4 portrait format at the outset, and I have gone for a 1:10 scale diagram of the proof-of-concept (POC), which itself is base upon a 32" outline... and indeed 32" propellers.

Suppliers like T-motor work in metric until talking about propellers, when in deference to the US ~ who invented flying ~ they switch to inches instead. And for the POC I am using what I have in the workshop in the form of 32" propellers fitted to T-motor U13s. 

And the nice thing about the design is that the perimeter lengths match the same diameter of 32" because the three-way connectors that join them together add a further inch to either side (so that the OUTSIDE dimension of the square is 34"). 

As the motors will be pitched centrally on the inch-wide connectors their axes are pitched 33" apart, allowing for blade clearance. So we'll order 4 x 32" x 1/16" lengths of alloy in order to define the 'square-frame' that supports the power-plants.

I guessed at the size of the centre-section and at 16" square it seems to fit the job. Accordingly, with the inside dimensions of the square-frame set at 32" there is eight inches of clearance all around the centre-section. Nonetheless we must subtract the one-inch width of each of the abutting cantilevers, which takes us down to 23".

Beyond that there are threaded inserts in either end of the cantilevers in order to fix the abutment and connect the flight-deck to the square-frame. From our mock-up we saw that a couple of connectors run to around 3/8th inch, so we have the following to order from our tube stockist:

    (a)    4 off at 32" x 1/16" perimeter lengths (total 128")

    (b)    4 off at 22⅝" x 1/16" cantilevers (circa 96")

This adds up to 224" or 5.67 metres in the UK, good if you can find stock lengths of six metres, but bad if like my supplier they only do five. Nonetheless I've enough left-overs to make a start. 

However a quick look at retail sites in the US like:

... reveals that 288" is a stock length, so you've enough left over for four legs too!

How long are the legs going to be? Well I haven't decided yet and I shall deal with it at the same time as the landing skids, which can be tailored to operational circs. There's a precedent for this, as an image search on 'Hughes 500' shows longer and shorter legs over the course of history.

FAQ Dave from Oklahoma asks, "Should I be nervous seeing that the centre-section appears to be overlapped by the prop-disks?"

ANS When will this generation listen? The motors pitch the props higher, and their efflux funnels considerably, reducing any losses. The mannekin will be set above the line of the disks anyhow, as we saw recently in the scriptures:

"And Colin raised them in their hour of need, above the line of their rotor-disks."

Sunday, June 13, 2021

Sod It, Let's Quad It...

Some of my best and worst thinking takes place at 04:00 a.m. and not least because I might well have had a skinful. At this, the 'darkest time before the dawn' that every airline pilot knows to be bollocks, I can't help thinking that all of this is just a belated effort to revisit a wasted youth in which I'd forgone the chance to fly helicopters.

The REM-fuelled dreams on falling asleep again at this hour are equally vivid, and in this morning's instalment I'm visited by a posse of tax-inspectors whose leader I pin down and stab to death with an item from a geometry set ~ the dreams in which other people are dying are the best I've ever had, as Donnie Darko sang.

It's around this time that I also revisit the outline to see if it can be made yet simpler, and wonder if there's an argument for using the same frame to build a quad instead. Turns out there is. Upping those propellers from three to six feet still allows for a respectable two-feet square centre-body, which can be extended as we've seen once pitched above the level of the disks.

The skids are therefore set at about a six-feet width, which will get you through the garage door and onto the back of a flat-bed trailer... all of which I shall recommend to my contact in California as the simplest solution to the question of a kit-build eVTOL. Beside the skids it can be made from just four parts each of arm, perimeter and leg, together with a similar number of connectors or castors.

All I've really done in life is day-dream, fly aircraft or visit transport museums and I do like people who reduce a part-count. Visiting one such place in Arnhem revealed how two Eastern Europeans reduced the components of the STEN gun by two-thirds, after which it became the side-arm of choice for the French resistance.

Furthermore I've much of the material to get Monty the Mannekin flying at half-scale right here and at a weight that won't attract the attentions of the CAA inspectors... whom I could always stab to death with a piece from a geometry set, worst case.

Fact is, the market for eVTOLs is rapidly polarising. The money is on winged types like the one just afforded a two billion dollar valuation in the form of Vertical Aerospace. Their offering is like practically every other out there, a format that was pioneered elsewhere at radio-model scale very many years ago.

But electrical air-taxis occupy a moneyed world of who-you-know rather than what, which has led the Vertical Flight Society (VFS) to declare the multicopter prematurely dead; although hummingbirds, commercial drones or for that matter the manufacturer of the Osprey or Chinook seem to have done well out of it. Some or other dirt-bag like me will inevitably find a way to make these things too ubiquitous to ignore.

"The multicopter is dead. Long live the multicopter!"

Saturday, June 12, 2021

Home-Build Guide #29

Turns out it wasn't the 300th post, but this is. Here's the inspiration from the original patent filed a few years back, and as you can see all that I have done is to join the dots in a much sturdier frame altogether. The logic stands, however, in that the eight motors can actually be addressed as a 'virtual' quadcopter.

(Alternatively those motors at the corners can be used for steering alone, whilst those between might address lift alone, so that the conventional cyclic, collective and yaw controls associated with helicopters might still be incorporated.)

Addressed as a quad, each pair of motors would rotate in the same direction, which is not what you would expect of an octo. Life's full of surprises, isn't it?

Whether these efforts come to fruition ~ or whether I return to the double-decked design currently simmering on the back-burner ~ is up to fate itself.

Home-Build Guide #28

What we have to remember however is that propeller disks are practically invisible and this is how the airframe would broadly look in operation, for which visualisation I have added a single propeller. The advantages of the airframe for transport is obvious from this, in that each of the propellers can be aligned with the frame when at rest. 

To complete a working prototype, the batteries would be suspended in a tray beneath the main deck, which itself would support the electronics associated with controlling drones. This would also support a plinth with which to accommodate a standing or seated operator, fixed at four corners using the hard-points previously incorporated.

As a practical flat-packed GEV or PAV I believe it passes muster, and as this is the blogs 300th post in pursuit of a practical 'flying carpet', frankly I don't care whether anyone likes it or not...

Home-Build Guide #27

How things look with the rotors in place. It is clear that by shrouding the surrounds (to some extent or another by extending the flight deck), more efficient lift might be contrived.

Home-Build Guide #26

And the brackets are riveted to the perimeter frame. They'll will be wired from each corner of the flight-deck, and as we see later that can be operated as a single entity. In other words, a virtual quadcopter in which two rotor replace each single rotor for a smoother ride, cheaper components, a measure of redundancy and a more compact footprint.

Home-Build Guide #25

The motors will be addressed by the control logic and wiring in pairs, and so I cut out a pair of dog-bone brackets not unlike those used on industrial drones. except double-ended in this instance. Plus they're plywood for the mock-up and not laser-cut carbon fibre sheet.

Home-Build Guide #24

"And on the third day, Colin created a beast of the air. And he saw that it was good." It pays at the start of each day in the workshop to visualise, to pause and create a mock-up of the mock-up, or a mother of all mock-ups.

First impressions? Well historically my machines have lacked adequate clearance from blade-strike, and I like the stance of this one... redolent of the legendary Hughes 500 known in Vietnam as 'Little Bird' and I name this one 'Even Smaller Bird'.

It looks somewhat 'lumpen', rendered as it is with inch-square alloy that should be half as thick. This however is because commonly most material comes measured by the inch, or 25 millimetres.

I like its compactness. It sits there and says, "Fuck you, your'e never going to be more compact than me." I do wish it was more refined in its use of language like me though.

You will be thinking ~ though I'm not ~ that it looks like a human salami slicer. That however is why we incorporated those hard-points: for we are going to raise the flight deck on a par with the disks, from whence our protection will come.

Join me now if you would by praising me in singing:

You raise me up, so I can stand on drones
You raise me up, to fly over stormy seas
I am strong, when I am on your flight-deck
You raise me up to more than I can be,
or at least as high as the rotor-disks.

Friday, June 11, 2021

Home-Build Guide #23

Weight-wise, where are we? Well the basic chassis weighs just eight pounds, though the bulk of the weight in electrical air vehicles, like cars, lies in the batteries and motors that are yet to be fitted. With road vehicles you can be fairly liberal with these goods, but in aircraft in particular there is a diminishing return from simply adding more packs of batteries in an effort to create more lift from larger motors.

The build philosophy therefore is strictly to start light and to go lighter, and as a part of that effort the comparative weight of the airframe has to be almost negligible. We can go part way toward that in alloy, but much further with carbon-fibre.

But then Rome wasn't built in a day was it... even in brick?

Home-Build Guide #22

We're over at the paint-shop here about six inches distant from the assembly line, and she's in for a coat of shiny red paint. Here at TELEDRONE in the UK we've a penchant for using post-box red. This stems from the days of designing drones that looked like flying telephone-booths, until such time as realising that nobody wanted one. Actually they did, they just didn't want to pay for it.

It was this Zen-like revelation that brought us here together in our efforts to build a universal 'flying carpet' to fulfil our wildest fantasies, whilst making me extremely rich.

In our next episode, expect me to be mounting the motors. If I'd known that that was all I'd be mounting on a Friday night, I think I'd have given up a long time ago.

Home-Build Guide #21

I've co-opted our test-pilot Monty the Mannekin, who's done tours of duty in Helmand province besides Mothercare in Croydon. Monty is a half-scale dummy, but don't ever let him hear you say that. As a result he is overly large for the mock-up, but gives you an idea of where we are headed. He will also come into his own once we replace this mock-up with a near full-scale model using 32" propellers in place of the twelve-inch vinyl that we're blessed with here.

There's still a chance at this stage of gratuitous sex if you tell people you build sleds for underprivileged kids.

Home-Build Guide #20

Here I've attached the skids ~ pointing in the right direction ~ using 40 x 6 mm bolts that are countersunk so as not to catch whichever surfaces we might be alighting on. Note too (by standing on the upright structure if necessary) that we're weak in the side-load department until such time as we fit shear webs as shown, in the form of the sort of brackets used for building kitchen cabinets. They cost just pennies, and got from the legendary Garners' in Skelmersdale, ironmongers to the mining trade since 1878.

The brackets also include pre-drilled holes matching the size of my pop-rivets, which is a marriage made in heaven if ever there was one.


Home-Build Guide #19

In order not to spoil it all as I did earlier by drilling the wrong face of the tubing in question, here I have turned the skids through ninety degrees. Now, and as indicated by the pointy rubber glove, we take our spare length and mark where the skid should meet the struts at each of the four corners of the airframe perimeter. The ballast is to keep everything steady in place of the more professional jig, which we're not into here.

Home-Build Guide #18

I've gone for shorter skids than anticipated, and in fact they're off a previous build and cut in half. It is therefore going to be something of an Apache Short-bow, and note that the horns of the skids are cut-offs that I've used repeatedly. They are secured here by a 20mm by 20mm timber insert to which they are glued, with a pop-rivet or two to secure.

The trailing ends have domed inserts, which for square as against circular sections are generally rounded ends rather than domes, and therefore the rounded edges should be set top and bottom of the skid (instead of either side), as this provides curvature at the rear end beside the front. Think reversible snowboards.

Home-Build Guide #17

For the stanchions/legs/struts in each corner I've used surplus 18 gauge inch-square aluminium of a length of around six inches, allowing this time for just one tube insert viz. M6 threaded at the bottom end. At the top end the alloy tubing runs flush to the uppermost reach of the three-way connector.

At this stage if you've people over for dinner and you are able to persuade them that it's a genuine Bauhaus coffee-table, then sell at a profit and get out while the going is good.

Home-Build Guide #16

With the flight-deck in situ, and bearing in mind that this is a third-scale mock-up, now is the time to stress-test the construction. I'm pushing a post-pandemic twelve stone here, and there's barely a murmur from my 18-gauge alloys. "She's a fine vessel sir, and no mistake." I say to myself.

In fact it should feel like the sprung dance-floor in Blackpool's Tower Ballroom, as in the TV series Strictly Come Droning.

Of course a 1" square section is too large at this scale anyway, so as we scale up we're likely to stick with it, increasing the thickness as we go. We'll go a long way on 1/16th inch instead, whilst we can only dream of working in 1/8th. And we've yet to begin to talk about aviation grade alloys!

(And though I've always been a bit of a metal-basher, there's carbon-fibre tubes for the fledglings amongst us too.)

Take a break, for this afternoon I'll be putting the skids under us all.

Home-Build Guide #15

NOTE OF CAUTION, because I make a major-league mistake here in starting to drill from the top, when of course I should have gone in from the sides... having glued the three-way tube-connectors in place yesterday evening.

NOTE TO SELF, refrain from gluing connectors in place until after this stage of build. This is because it is much easier to drill from above ~ as seen here ~ and then turn all of the tubes through ninety degrees.

There's a lot of trial and error in this game, for as the great industrialist James Dyson observed, "You learn nothing until you start building".

If you want to avoid your prototype looking like a Swiss cheese, follow the master.

Home-Build Guide #14

Now children, we need to fit our flight-deck to the perimeter, don't we?

There's a bit of a gap here and there and so I've centred it broadly and pinned it to the floor with a bit of ballast whilst I mark where the external bolt-holes need locating.

Note the sign "U/side" and the stanchions (or legs to you) all point upwards here, with the airframe inverted.

Home-Build Guide #13

The coup-de-grace, and I fit the lower skin of the flight-deck and tighten the bolts up after riveting as previous. Those are M6 bolts, beloved of the Honda motorbikes I used as a teenager, and they are driven into the ends of the rotor-arms. If you want to go belt-and-braces, glue them in to and pop-rivet all round.

The FAA might be chary of the method in the absence of welding, but believe me you could hang one of your neighbours without these babies giving way.

If you are really anal, however, you can drive a threaded rod in steel (heavy) or nylon (light) all the way through from one end to the other... but my way's the high way.

Note the all important "U/side" moniker in permanent marker, essential if your Huey-style skids are not to be fitted facing the wrong way up.

Home-Build Guide #12

A cheeky little tip this one, but one that will save you tears and regret further down the line. Mark the sides adjacent the hard-point material, adding if you wish an arrow at this stage to say which way the drone will be flying. This is essential in order that you are not facing backwards whilst the vehicle is in motion.

I mean, fuck, what are we building here, a Tesla 3? 

Home-Build Guide #11

Now I opt for a low-density insulation foam of the sort the manufacturers fit to high-rise buildings without telling the residents that they're highly flammable, because that way there's more money to be made... although I realise now that this is the last time Celotex are likely to let me use their product.

There is admittedly a 'health and safety' advisory printed on the sheet, so they can't be all that bad, can they?

I'll let you read that while I drink my cappuccino, and you can tell me all about it later.

(You can tell this guy was an airline captain, huh?).

Home-Build Guide #10

With the hard-points installed, run another bead of sealant along their edges. Some of you ask me, "Do these run along the sides, or across the leading and trailing edges?".

I ask them in turn if they still need me to wipe their bottom.

Home-Build Guide #9

Here we flip the flight-deck over, and run around the perimeter with a silicone bead. Waiting to be fixed are the 'hard-points' within the airframe, used on fighter-jets for things like drop-tanks and missile-rails, but which here will later support a nice chair.

The hard-point material is unplanned inch-thick timber from Rosbotham's around the corner here. As an off-cut, they let me have it gratis.

"Up yours BAE Systems, our hard-points are for free."

Home-Build Guide #8

You should be enjoying this by now and if you're not, you need another hobby. The next job involves sealant and so I've donned fatigues and cleared the garage using my .22 calibre mastic-gun.

Home-Build Guide #7

With the abutments bolted just hand-tight, we can overlay some 1.50 millimetre sheet and rivet it to the rotor-arms to fix the geometry. I've used leftover material, and in fact this is its third outing... another advantage of alloys over exotics. What this means here however is that it is slightly undersized at 12" square instead of 12.5", although we can live with this as it'll be in the museum at Oshkosh one day, warts and all.

Using 12 x 4 mm pop-rivets, fix a couple into each side of the square before loosening the bolts again prior to drilling the corners. During the great pandemic lockdown of 2020 I bust a drill-bit by not removing those bolts first. What, with all those hardware stores closed, "Fuck," I said.

Home-Build Guide #6

With the centres marked and punched, we can go ahead and drill as seen from on top as the great advantage of square alloy sections is that they can be turned through 90 degrees to simplify construction.

Home-Build Guide #5

Recommend not working too late into the evening on these builds, as fatigue leads to mistakes. Re-starting therefore at daybreak (plus five) I loosely arrange the rotor-arms and using a length of off-cut, mark where the bolt-holes have to be drilled within the four-way flight-deck.

Thursday, June 10, 2021

Home-Build Guide #4

Reverted here to a platform I developed independently and which we showcased at the GoFly Challenge in California in February of 2020.

What it does is to brace the outer airframe by incorporating a shear web in the form of the sandwich laminate which forms the core of the central flight-deck.

It works logically too, because each arm provides a pathway for the wiring to each pair of motors, which can be addressed in various ways to suit the operating environment.

I'll call it quits having started late in the day, but the focus of the full-scale self-build TELEDRONE that I'm designing here for a client in California is ~ literally ~ to be a 'day job'.

And that's in term of the time taken to construct, rather than a career path.

Home-Build Guide #3

I've cut just one arm to length at present by way of a how-goes-it? As Oscar Wilde once said, "To cut one rotor-arm too short may be regarded as a misfortune, to cut four looks like carelessness."

Note the tube inserts at either end, which contain an M6 bolt whose purpose is set to be revealed in a forthcoming episode.

Home-Build Guide #2

In order to pitch the support arms for the flight-deck broadly between the gaps made by the swept area of the propellers, it's been produced as a template 12.5" square. Then there's a margin drawn around its perimeter to represent the 1" width of those arms.

This reveals that allowing for the inserts at either end ~ which together account for 3/8" ~ that we need arms of around 16 & 7/8" in length.

Home-Build Guide #1

I've gone for a 1/3rd scale mock-up... the late Belgian conceptual artist Panamarenko was a great fan of the Great British 'mock-up'.

For alloy tubing I've selected Simmal's (Preston) 1" by 18 swg, five metres off at a cost of £18, thank you. These I've cut to 24" apiece, and insert into Cotel's (Barnsley) three-way tube connectors, model 8061. They're German-manufactured and come in a steel-reinforced version for big boys' (or girls') toys.

The tube-inserts in question will fit the next gauge up (1/16th of an inch) more closely, and so here I've inserted a touch of silicone/mastic/caulk to take up the slack.

Doodle Bug

Kitchen table stuff, but if there's a better way to raise your backside into the air then I'd be pleased to hear it. Quads are a straightforward arrangement around a square while octocopters almost invariably string the disks out like a ring of roses. Admittedly there is no escaping the fact that propellers describe a circular path, but beyond that the world prefers square. And after that, ideally flat-packed.

So I run the numbers. Jetson at look closest to sales of a viable vehicle, and are running at around 84kW of installed power. However, their propellers are co-located, and contra-rotating props lose anywhere between 20% and 25% of their efficiency. This brings them level with Napkin Man's own target of eight motors at 8kW peak apiece.

(The only exception to this is the double-decker prototypes I have developed to date, which space a pair of quads around a vertical accommodation booth. Nonetheless in the hover and at zero airspeed, the lower quad is still operating in the wake of the upper. This is optimal for outlining the smallest possible footprint, but sub-optimal as viewed from aerodynamic efficiency.)

I contrast and compare with a straightforward quad, and by way of rule-of-thumb I've opted for 40" props on the Octo and 60" on the quad. These pan out at around the seventy and eighty square feet of disk-area respectively, but then the eight entrains a compact downdraft of air that ought to make up for the missing ten percent of thrust.

Furthermore, it can be shrouded such that the ground-effect cushion is optimised and at the same time provides a larger deck altogether with which to accommodate say a comfy chair: around 40" square as against 20".

And there's more. Upfront costs are broadly comparable (the smaller equipment often half the cost of the larger, so that the eight motors considered here are actually cheaper than the four larger motors otherwise required). Likewise maintenance costs are lower, the smaller propellers replaceable at a lower cost following the inevitable damage. In fact the only element likely to prove more expensive an outlay ~ and to an acceptable degree ~ are the speed controllers (ESCs).

Still it gets better. With the skids pitched 82" apart on each outline, the quad still has a larger overhang ~ 30" as against 20" either side. In practical terms this means that the octocopter's skids can be set upon lower legs, which in turn reduces the material costs beside the weight. It also ups the structural integrity, which again allows for a thinner gauge of aluminium tubing within the airframe.

Aviation invariably features virtuous circles of this kind, which inevitably come to be compromised somewhere along the line. Trick is to design for the lightest, smallest of designs at the outset. It's how automobiles started out, and what are we doing if not building vehicles in the air?

Finally, we estimated ~ my power supplier not working exclusively with aircraft ~ that we might get around 30 kilos of thrust apiece from each motor-and-rotor, providing a peak quarter metric ton of lift. It's at the margins of acceptability, but better to plan for the lowest possible outlay and work upward thereafter.

Nobody was born knowing how to walk. Actually I was, but I had better things to do.

Wednesday, June 9, 2021

Satanic I/P Rites

The design's gone mainstream, as can be seen from Alta's survey drone. But what? 

Well until fairly recently there were only two outlines for the arms of a quadcopter, and they were the 'X' and 'H' configurations.

Until I came along, and suggested that four cantilevers abutted each other and fixed between plates was altogether easier once drones got that much bigger.

Except that I was late to the party, and whilst the outline appears in my own patent specification ~ and possibly preceded the many Lego builders who arrived at the same conclusion ~ the prize appears to go to a German technical university. They patented the same means of construction as far back as 2014.

Except that the 'Son of Sam' documentary series on Netflix points elsewhere. Both the notorious New York serial killer himself and (possibly) Charles Manson were influenced by the Process cult concocted by a pair of Carnaby Street loons in '60s London.

In my defence, and looking at their material below (where else?), note that I invariably draw this four-pronged set of rotor-arms with a left bias, and therefore a mirror image of that on the cover of the magazine. 

Accordingly as CEO of TELEDRONE and in the spirit of the times, I have approved the following press release:

"At no time in past or present has our aerial platform project been involved in serial killing, seduction, satan worship, sacrifice or ~ chance would be a fine thing ~ casual sexual encounters. We strongly condemn the co-opting by cults of quadcopter layouts, except as a means of blood-letting among consenting test-pilots. And although our CEO has visited San Fransisco, at no time did he wear flowers in his hair. Indeed, he hasn't got any. Hair that is, not flowers."

Tuesday, June 8, 2021

UK CAA's CAP on Innovation

Doesn't take long to realise that the 238 pages of this tome relating to flying radio-control models of one size or another is designed to exclude most people who might still wish to do so in the UK, so far as is possible. The requirements now barely differ between models, in fact, and full-sized aircraft up to and including airliners... at least from the pilot-operators point of view. In fact, somewhat more complex as there'd be more paperwork required of me doing this than, say, flying an Airbus on a daily basis.

Much of this has come about because of the UK CAA's piss-poor oversight of Alauda's appearance at the Goodwood Festival of Speed, resulting in a roasting by the AAIB. As a consequence it is now altogether easier to develop personal air mobility in Australia, from where Alauda came in order to shit on our doorstep, than it is here. The video commented upon yesterday...

... is something you'd be waiting a long time to see here in the UK.

Which is of course exactly how they'd like it. The Large Model Association ~ to whom responsibility for much of this is delegated, they knowing more about it than the CAA ~ recently complained (!) that one member had written to the Transport Secretary to say that he was effectively destroying radio-controlled modelling in the UK.

Truth to power I'd say, though not that power ever worried.