Fibre Weight-Loss Program

With final assembly and testing set for the second week in May, some deliberations in the run-up (and reasons to avoid embarking on similar projects of your own if you can possibly do so). In fact in answer to the question, 'Do you ever feel like throwing in the towel?' my answer is 'Only on a daily basis'.

Necessity is though the mother of invention and the four motors we currently (!) have are insufficient in themselves to raise the payload, which is why we'll need four more at the base. A decision has been made though to address all eight motors to steer the vehicle, albeit from a single controller mounted up top.

The upper drone has been reverted to alloy at the cost of extra weight, and with both drones now doing the steering we cannot afford undue flexure in either, and thus the lower drone might need modifying in the same way too... at cost of extra weight again.

There is an option to equip the top or bottom drone with larger motors and propellers ~ an example of the flexibility of the design itself ~ although a factory just along the road here seems able to provide square carbon-fibre tubes that are of course the Holy Grail for makers of mega-drones like myself.

It was of course only a matter of time, though with Jetson calling upon the services of super-car manufacturer Koenigsegg to provide their own carbon-fibre parts, the move is better made sooner rather than later.

Tubular Bills

Fit the rotor arms left and right and relocate the batteries to ensure the leads from the ESCs will be long enough to address the central controller. There is an argument for these outriggers to be round tubes clipped onto the corner posts, with the motors mounted conventionally... though that can wait. Meantime the schedule for flight-testing has slipped. More to follow, Rome not having been built in a day.

RUDdy Hell!

Elon Musk's rocket undergoes a Rapid Unscheduled Disassembly while my own efforts to launch a mannekin vertically continue. While I await a firm date for the test-flights I take the opportunity to tweak the design to make it ever more functional. Instead of fixing the motors direct to the airframe I revert to a four-poster arrangement so as to mount the motors to removable outriggers. They're shown here in aluminium, but are set to be replaced by plastic to reduce their weight.

The same arrangement suits upper and lower drones so that they appear identical, and the outriggers themselves form an ideal location for the battery-packs and speed controllers. In the case of this prototype, however, the packs will be fastened to the mounts already fitted to each prong of the centre-section.

Merlin's Drone

Am accompanied working in the back yard by the sound of a Merlin overhead, which is engaged in pleasure flying from the local field... and merits a break in the proceedings. 

Re: Render

With the upper drone re-rendered in alloy to up the stiffness, it's off to the paint shop to be resprayed in black. This drone has been now been built thrice: twice in alloy and once in plastic extrusion. The lower drone retains its all-plastic construction in view of the fact that its will be providing a constant force of lift at its four corners, which will not result in the same twisting moments. A benefit of ascribing collective lift to one of the drones and cyclic to the other is that the former can be run efficiently at a higher power setting, as no differential is required between any one motor relative to another.

And yes, it is the UK's first kit-built Velocity SE that's taking shape in the background; Burt (Rutan) like the Buckminster of previous post being another formative influence.

Re: Launch

It's not just the SpaceX launch that is delayed, though we're still set for final assembly and flight-testing during the closing week of this month. After discussions with Angus, who'll be doing the tuning and flying, we opt to revert to alloy for the upper drone that will be doing the steering ~ so as to improve stiffness at the cost of additional weight.

Meanwhile the lower drone remains almost wholly plastic, as its motors will merely be supplying the heavy lifting at this stage of the game. I sub the feet for skids, a feature of this drone being the fact that it can be used either way up (skids here uppermost). In fact there is an argument for flying it this way up, which we'll do for the test-flights, as it reduces the vertical extent of the vehicle and reduces the static loading of this structure whilst it is at rest on the ground.

Seen as here it has merely to hoist the payload into the air, with motors mounted on those stubs. Otherwise it (and the undercarriage) would need to support the entire weight of the payload and upper drone, whereas otherwise that function is fulfilled by the ground itself.

I've always been interested in the structural aspects beside the aesthetic and will ever err on the practical side. Buckminster Fuller was expelled from Harvard for not towing the party line, and became an alcoholic in his early thirties ~ whereupon he resolved to design innovative structures for the benefit of humanity.

If I've any advice at all for my son, it is not to fear dropping out ~ for we live in a world fashioned by freaks and failures.

While you wait...

A picture of the only all-round hovercraft service still existing, from the south coast of England to the Isle of Wight in just ten minutes. You once required a commercial pilot licence to fly it, whereas now it requires a master mariner's certificate... or five year's of your life.

Month-End Update

Transport the sub-scale proof-of-concept to the consultant tasked with the wiring, tuning and flying. Good news, no reason to see why it won't be a 'flyer'. Bad is that the plastic perimeter frame needs to be changed to alloy to stiffen it prior motor fitment. This is scheduled for mid-April, the second half of the month devoted to the assembly  and flight-testing. With this complete the POC may yet be exhibited at the LMA's expo at the RAF Museum in Cosford, where ideally it will live out the remainder of its days hanging from the rafters.

Further update mid-April, therefore...