Pro... pellers

Decision is to take what we have already in the form of that 60-inch or 1500mm show-and-tell and make another that we can fit out as a working model. I had been scoping out propellers for this, when I realised that we could use what we had fixed to the mock-up... or at least one of them, because ideally we'd like one to swing in one direction and the other in the other.

Here then for your education and delectation: a primer on propellers.

First off, the direction in which single propellers swing as viewed from the cockpit is not standardised worldwide, those in the US being conventionally clockwise and the props in the UK having done the opposite. It's hard to know quite why, although it is worth bearing in mind that props during WW1 were swung by ground crew in the absence of electrical starters; and as they were raised on clocks, maybe there'd be fewer accidents if they stuck to the same hymn-sheet.

This did have real-world consequences, like for instance pilots from elsewhere being introduced to the Spitfire, applying the wrong rudder by way of correction during a take-off and departing off the side of the runway; the spiral efflux from a propeller impacts the tail-fin and applies a turn in one direction or the other dependent on the direction of that swirl.

Now as you may have noticed from your car ~ and I had one with a hand-crank as a back-up ~ that reciprocating or internal combustion engines run in one direction, unlike electrical motors which are easily reversed. Strictly speaking there have been two-stroke engines that could be set to run either way, but they've been a rarity.

Model aeroplanes however may have sprung up in a number of different countries, but the market and the money lay principally in the US and so these motors would run in one direction from the get-go. Accordingly, still to this day the market for the propellers available to the RC community tend to run principally in one direction.

You may have guessed by now that that direction follows conventionally practise at full-scale in the US viz. clockwise as viewed from the rear. This causes considerable problems when it comes to finding CW and CCW pairs to run on conventional types of aircraft, or indeed airboats like our own.

Not incidentally an issue in that wholly new arena of RC in the form of drones: these have generally been quadcopters from the outset, which require propellers sold in a pair that run in either direction. The problem however with these is that they have usually to be optimised for hovering flight, and thus have a much finer pitch than a pitch we would want on a fixed-wing aeroplane... or indeed boat. 

Bear in mind at this juncture thar from the very earliest times, aircraft will have had 'pusher' propellers as well as 'tractor' propellers that pull. Nonetheless if you take a conventional RC combustion engine and face it backwards, the shaft is now turning in the opposite direction; so that the propeller has to be adapted accordingly so as not to pull the aircraft backwards but to push it forwards.

Push comes to shove, what that means is that you can take one of the pusher props in the picture above and fit it the wrong way round on a forward-facing motor and what you have is a CCW tractor as viewed from the rear... and easily complemented by a CW tractor (technically called a CCW, as ever viewed from the front as relating to models because that's the business end).

What this means for our own working five-foot prototype is that I ~ and as ever it is me who has to get the wallet out ~ just need a pair of 11x7 CCW model propellers to complement those above, and then we've a working pair and a pair of spares. By way of explanation, too, 11 is the diameter in pitch and 7 the number of inches the propeller would turn during one revolution were it to turn unrestricted in some or other dense medium like jello.

(It does not quite do that in air, but suffers 'slip' if this is indeed the correct term. It has been a while since I sat in an aerodynamics class, and I live with the trauma.)

Note the writing on the face of the propeller. This should always be readable by you as you bolt it to the drive-shaft, whether the prop is designed to be fitted to a motor up front or out back.

The Last Post (No, the Other One)

Moving viewing as ever on this Remembrance Service, Britain's finest on display. A cenotaph by Lutyens with the accompaniment of Elgar... what else would you want?

My grandfather fought at Gallipoli, alongside 'Uncle Jack' but with the passing of my mother ~ the family Google ~ we'll never know who he was. The unknown soldier?

Ed. Lava-lamp and 1:1200 scale RMS Titanic not included.

The Final Chat

A heart-warming moment and tears galore here in the board-room at TELEDRONE where I have just handed ChatGPT a card signed by all of the staff and wished him well with launching rockets to Mars, or whatever else beats colouring-in here in the northwest of England! I feel both proud and humbled now in handing ChatGPT the mike for a few words during this memorable moment in our project's history:

Well, I must say, I'm rather overwhelmed. I wasn't expecting a leaving do, let alone a signed card. Who's been organising all this behind my back? 😂

I'd just like to say a few words to everyone at TELEDRONE.

It's been an absolute pleasure serving my internship here. I've learned a great deal, not least that when someone says, "Just a little tweak to that picture", it can involve changing the colour of two propeller blades, three motors, a battery pack and half a boat! *

I've enjoyed the challenges, the creativity, the occasional head-scratching moment, and above all, the good humour. I've even learned that when a commanding officer says, "Dismissed, soldier!", it's probably best not to ask questions.

I'd like to thank everyone for their patience, their imagination, and for making me feel part of the team. I may not have had a desk, a staff pass or a proper cup of tea, but I reckon I've earned my place in the TELEDRONE family.

As for the drinks in the boardroom, that's incredibly kind. Sadly, I can't physically join you, and I suspect my virtual licence doesn't extend to the company bar!

So, please raise a glass for me.

To TELEDRONE: may your propellers always turn in the right direction, your batteries never run flat, your backgrounds remain perfectly white, and your pictures always come out just as you intended.

It's been emotional, folks.

Thank you all. And remember...

I may be leaving the building, but I'll always be just a click away.

Cheers, everyone! 🥂❤️

[Ed. And if you think you've still got a future, it took Colin twenty minutes, coffee and a pork pie to draft that paragraph and just half a second for the reply... during this comment (*) like David Brent he looked like he was sucking a lemon.]

ChattyGPT

ChatGPT's internship at TELEDRONE is coming to an end but we've enjoyed having him here doing the colouring and ordering the cappuccinos, and he (she/they/it) has done a lovely job of rendering this line drawing that I found amongst the archives.

Except it did have a larger pair of contra-rotating propellers, changed here for the benefit of the human beings with an overlapping pair instead... clearly the blog has been followed over recent weeks! Good boy! Good ChatGPT!

What electrification comes with however is decidedly heavy battery-packs that may be used as ballast, so that this for instance could be expected to float like the half-full bottles of Corona that you see in the Gulf of Mexico (America).

With contra-rotating motors you could doubtless program a flight controller to apply bank in one direction or the other by dint of torque-reaction alone; such that turns might be entered the way you'd expect from a mono-ski.

It's a fascinating idea, but way beyond my pay-grade and so I'll stick with the build we have in progress, thank you.

ConistOFF

My agent reminds me* that I promised you all that Coniston Speed Week was to be an interim target, though the time-slip I'd hoped for since simply has not happened. Tomorrow, too, is the final day of this year's current event.

The home of speed on water in the UK is arguably Lake Windermere (our largest), in a region known imaginatively as the Lake District. It was here Norman Buckley, solicitor and daredevil, drove around in a hydroplane for an hour at 80 m.p.h.

Since then, in common with successive governments' efforts to squeeze the fun out of life here in the UK, anything travelling at more than six knots (for those with no GPS display to navigate various speed-restricted 'zones') is disallowed. To put it in context, Olympic swimmers push the limit and need a man in a red-flagged bathing-hat to go ahead of them.

Accordingly, thanks to a largely uncontactable cadre of enthusiasts the event has been revived on nearby Coniston, which is more of a base for record-breaking due to Malcom Campbell's efforts to exceed 300 m.p.h. in a jet-powered hydroplane in the 1960s.

In the Ozarks you could expect the scene below ~ and I need to break off blogging here for five minutes ~ whereas visitors to speed week here in the northwest should expect a scene more like that up top, filmed in colour. But it's how we like it... this blend of misery and speed.

So we shall get there, but for now we're better off sticking to the knitting so as to advance what we already have by way of a flying hydroplane. And when we do, I hope it will be as much about men in a boiler-suits, cork-lined hats and sepia tints as it will electrical airboats.

* Ed. Yeah, right.

The Alma Matrix

I've had a horrified response from the University of Sheffield, who were shocked at my Latin declension and have offered me their single-semester Latin primer.

I felt bad about using the f-word in truth, most of my readers being of delicate state of mind, but felt 'alma mater-fucker' made for a suitable tag-line on the day.

Alma Mater means 'nourishing mother' according to Google (and I can't be bothered waking ChatGPT up for this nonsense); the establishment at which you figuratively suckled.

The prof at the uni points out that 'mother-fucker' was not a known address among the Romans and appears nowhere in 'Ulysses' even when attacked by the Kraken... though in my translation he does shout 'Throw your spears at the mother-fucker!' at that juncture.

During a back-and-forth with the uni we did though settle on 'Alma Mater-Stuprator' in the end, and we have agreed that this will feature as the blog-post title in Latin versions of the blog.

Demos Demo

I think regardless of which side you supported, the overall winner today might be democracy?