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98 February/March 2018 | Unmanned Systems Technology PS | Add lightness and ‘simplicate’ Q uite Interesting, usually abbreviated to QI, is a BBC game show predicated on the fact that most of what we think of as well-known facts are, in fact, wrong (writes Peter Donaldson). Take the engineering rule of thumb expressed as “add lightness and simplicate”. I would expect most engineers – particularly those with a love of cars – to attribute it to the founder and guiding light of Lotus, Colin Chapman. As would I. Naturally though, we’d all be wrong. There’s no doubt that Chapman used it as his engineering credo, but the expression was around long before he was, and a very similar variant – “simplicate and add more lightness” – is associated with the early 20th century automotive and aviation pioneer William Bushnell Stout, whose r&d work investigated both all-aluminium and all-glass fibre structures for cars, a form of active ride levelling, a flying car and, more practically for its time, the Ford Trimotor transport aircraft. But it may not have been him either, as the expression has been credited to a designer named Gordon Hooton, who worked for him. Whatever its origin, every engineer will viscerally appreciate the drive for the kind of efficiency it embodies and the subtle and sometimes adversarial relationship it has with cost and reliability, and the effect all these factors have on design. The relationship between simplicity and reliability for example is not, for want of a better word, simple. While simple machines have less to go wrong, that doesn’t mean they will go wrong less often or less seriously. A Vickers Vimy for example is a far simpler aircraft than an Airbus A380, but there’s no question that the latter is more likely to get you safely across the Atlantic than the WWI bomber that proved, in the hands of Alcock and Brown in 1919, that the crossing was feasible. Of course, this example is skewed by the best part of a century’s technological development, with every critical component and subsystem being orders of magnitude more reliable on a modern aeroplane than their equivalents were on the old-timer. However, the Airbus is also massively redundant and can afford failures in many systems before there is any real danger. Significant redundancy is not always appropriate for unmanned systems though, particularly those that must be designed and built to a price point. Our report in this issue on the ASV C-Cat 3 USV is a case in point, as Richard Daltry and his team chose to rely on selecting very reliable individual components with some conservative performance margins in certain systems to create an entry-level survey vehicle that promises to do its job and come back when called every time. In contrast, the Chinese hybrid multi- copter described in the Platform One section of this issue seems to be the result of its inventor’s pursuit of efficiency regardless of complexity. It is a brave attempt to harness the high-temperature steam exhaust of a fuel cell in a reaction drive system to supplement its electric motors. That’s quite complicated, but also quite interesting. Now, here’s a thing “ ” A Vickers Vimy is far simpler than an Airbus A380, but the latter is more likely to get you safely across the Atlantic