Half-Scale Build #2

I've inserted the tube-connectors with a little silicone sealant around the perimeters of the tube-ends, and then reinforced with a rivet. You need to do so with two of the perimeter lengths prior to sliding them into the remaining two like this.

Half-Scale Build #1

The tools of our trade. The reason I defer the use of professional fabricators able to draft and weld airframes ~ at least at prototyping stages ~ is so as not to be at their beck and call. I also promised that whatever we build, we can do so in the garage with hand-tools or else on the trestle-table indoors.

Clockwise from top left, silicone sealant. Don't use decorators caulk even if you've left overs, because it runs in the rain... as I can attest.

Pop-riveter, and I've found the cheap ones to have been as good as the expensive. My rivet of choice is the now-legendary 4mm by 12mm shank that requires three pumps of the gun.

Tube-connector, one off corner seen here. They do come with steel inserts which does up your game, albeit at the expense of considerable weight: must-have for passenger versions but not so much here.

Alloy tubing inch-by-sixteenth, drones for the use of.

Kamov...er all emotional

One of the most innovative and enduring of designs... this a Kamov-26.

David Gibbings R.I.P.

News from the British chapter of the Vertical Flight Society of the passing of one of its more illustrious members who after training at RAF Halton would go on to work as the flight-test engineer at Fairey and then Westland, where he was involved in practically every development.

Books on the Rotodyne are as few as its remaining parts, but what is clear is that the Harrier aside this ~ circa 1960 ~ was the last purely home-grown aerospace initiative to emerge from the UK. Westland, who took it over, chose to manufacture helicopters from elsewhere before needing rescue by foreign ownership.

Invariably this stems from the fact that ruling classes in the UK are drawn from arts instead of sciences, which are viewed with suspicion despite having been the basis of national prosperity. Margaret Thatcher was an exception to the rule (Chemistry), those like Liz Truss hoping to emulate her studying Politics, Philosophy and Economics...

...the essential subjects for people given more to talk than torque.

Airframe with eight motors arranged as in a conventional octocopter, and scaled here to represent 18" propellers, a 20" centre-section and 48" airframe. Demonstrates how a quadcopter is the better choice for proof-of-concept, from the point of view that the swept area of eight 18" propellers improves upon four 22" propellers by only 25%. This has to be offset as well against a 25% increase in size, along with the added cost and weight of four additional motors.

In fact the two kilos of thrust which an extra four motors provide at 60% rpm using a smaller propeller is offset by the surplus weight. This is the curse of the multicopter: requiring ever more motors to approach the safety of the helicopter, whilst sacrificing aerodynamic efficiency at every stage of the game.

It provides a more stable platform and ample redundancy with as many as sixteen motors fitted over-and-under. It's filed under Creative Commons attribution 4.0 too, so fill your boots.

Mock-Up

It all hangs together on the ground at least but probably looks better in 20mm gauge instead of 25-ish, but we'll run with it. There's an argument to eliminate the perimeter, which practically adds the weight of an extra frame-and-a-half, or at least in alloy.

That said, it offers three distinct advantages:

(a)    it supports four, eight or even sixteen motors with few mods.

(b)    it's more practical when it comes to storage and transport.

(c)    it normalises the direction of flight and helps shield the propellers.

You don't get to realise these advantages until such time as you're having to carry the thing around with you ~ or as James Dyson put it, You learn nothing until the build.

Which in my case I've scheduled for November 19th.

Watch this aerospace.

Cutting Metal

It's what they say in the airline industry when the design has been put to bed and the machining starts. Except in my case they did the cutting for me, and thanks to Simmal for bespoke lengths of inch-square tubing at sixteenth gauge.

Unlike the 'dog-bone' design some posts ago in support of eight motors, the airframe for the quad extends its outline four-square and thus uses a little over stock five-metre lengths of tubing.

What I've done here then is to divide the three components between the two lengths so as to be left with identical two-metre-plus offcuts:

Four off, airframe sides at 34" apiece.

Four off, cantilevers at 550mm apiece.

Four off, platform sides at 10" apiece.

(a) Note that the airframe sides are 34" because they are joined by right-angle connectors which each occupy an inch.

(b) Note that the cantilevers demarcating the centre-section are at 550mm because the overall length of 22" has to be foreshortened to allow for threaded inserts.

(c) Note that the passenger platform will match the centre-section at 12" square, from which 2" has been subtracted again to accommodate right-angle tube connectors.

A benefit of half-scale is that it fits the car, which means motors and electricals will not need weatherproofing for transport... as I've paid heavily for in the past.

I've suffered for my art, and now it's your turn.