Wednesday, January 6, 2021

Draft Design for 2021

From hereon in its design and build, with the emphasis moreso on the former in view of the third nationwide Coronaviral lockdown in the UK. Thus we begin with an outline drawn to scale, for the look-and-feel: And I looked, and saw that it was good.

A word on those dimensions first off, the one missing being the uprights at 1750mm with the break at the elbow-rests being at 1000mm (that being broadly customised to my own bodily dimensions).

Regards the lateral extent, this is optimised for both the trailer I've been using ~ the one-by-two metre flatbed ~ but it also reflects the sheet-metal suppliers stock unit that measures the same.

An optimal solution would be to increase the lateral measure to four feet, to suit the readily-available Imperial sheet metal stock measuring four feet by eight. This has the advantage that it squares off the foot-print of the drone, to suit conventional practise.

The passenger booth is formed of 1.50mm aluminium sheet to which 25mm foam is bonded as a core. The sheet itself is of a single piece, folded to form the sides. This material is fitted around a space-frame that outlines a vertical box-structure, likely to be of 2.0mm or ten-gauge square alloy section (or else carbon fibre at a thickness to be determined).

The deck and ceiling are of double-sided sandwich construction instead, fixed like the booth with 4.0mm x 12mm pop rivets, and cross-spars terminate in threaded stubs so that the "wing" braces (of material and size to be determined) can be connected using wing-nuts. By these means, upper and lower drones may be connected and the booth sandwiched between the two. The latter is fixed by an internal flange top and bottom formed of 25mm angle alloy.

Note that the booth can be turned through ninety degrees so as to operate in a sense perpendicular to that shown, in which event longitudinal skids might be attached to the ends of the cantilevered arms of the lower drone. For operation by previous means as illustrated, cone-spring undercarriage legs are fitted instead to coincide with each of the motor axes.

The proof-of-concept as outlined is designed around 125-amp ESCs and T-motor U13ii power-units, to which 32" carbon-fibre propellers are attached. The lower power-units are programmed initially for 'collective' lift alone, and the upper programmed for flight control or 'cyclic'. The vehicle is thus optimised for operations near to ground-effect, although replacement of the upper drone with an X-8 'over-and-under' configuration addresses the engine-failure case effectively, so as to allow for operations at altitude.

In either event, the lower set of propellers might be stopped for their protection in the take-off and landing phases (and aligned where necessary with the landing skids).

In the shape and form seen and at a weight of around 35-40kg without battery-packs, the airframe is intended for remote-controlled operation with and without a dummy under the 'large model' exemption provided by the UK CAA (expected to be reinstated shortly at the time of writing).

The design itself is aimed at the autonomous delivery of human passengers, although it is readily adaptable to piloted control using fly-by-wire methodology.

A commercial variant might be fitted with a hinged door coincident with the height of the side-panels, included subsequently within a windowed compartment of broader outline more consistent with the original concept outlining a 'flying phone-box'.