Seeking a soft landing
The elegant structure of a naturally evolved cat’s paw has inspired a new way to protect paratroopers’ legs. This adventure is sketched in a study called . The idea is to replace the current kind of shoe soles with something more resembling what one can find by disassembling a cat.
The need is great. Paratroopers, says the study, “have always been the personnel at the highest risk of injury in the military, and their lower extremity injuries account for the highest proportion of parachuting injuries”.
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The researchers obtained some cats’ paws. They analysed the structure, using histological staining techniques, and also micro-CT scans (yes, CAT scans of cats’ feet). That guided their attempt “to mimic the adipose tissue found in cat paw pads, which is formed by a subcutaneous layer enclosed within a dermal layer and exhibits typical viscoelastic behavior”.
Volunteers were taught to perform a standard half-squat parachute landing manoeuvre. This technique came in handy, so to speak, in a series of drop-landing tests: 10 drops from a height of 40 centimetres and 10 from twice that high. The study reports that the experimental soles were “secured to the subject’s feet by adhesive tape” and that the volunteers who had new soles fared fairly well, especially in the higher falls.
The study doesn’t dwell on cats’ famous ability to land on their feet when some unkind person turns them upside down and drops them from on high. The cat dropping, twisting and landing has been dissected in numerous scientific publications, including this column in years past, and also in many pubs.
A bit Heath Robinson
The cat’s-paw-pads-for-paratrooper-protection patent reminds Feedback, a little, of a granted to Gustano Pizzo in 1972. Pizzo engineered an electromechanical system to trap aeroplane hijackers. The system first drops a hijacker through trapdoors, seals them into a package, then drops the encapsulated hijacker through the aeroplane’s specially installed bomb-bay doors, whence they parachute to earth, where police, having been alerted by radio, await their arrival.
Pizzo’s invention is convoluted to a degree reminiscent of the intentionally over-complex devices drawn by cartoonists Heath Robinson and Rube Goldberg. Yet the Pizzo patent has been cited in at least 27 later patents by other inventors. One of them, , patented in 2005, shares some –but not all – of the capabilities Pizzo envisioned. Gleine added some new mechanisms: “Alarm signals and terrorist countermeasure devices such as fogging or tranquilizer gas generators, noise generators, high intensity blinding/glaring lights, a cabin lighting master shut-off, window darkening devices, and tranquilizer dart guns”.
To airline executives, the Pizzo and Gleine anti-hijacking inventions may have looked too costly, or too advanced. , granted the year after Gleine’s, is an alternative. Egeresi would position a flexible stainless steel net behind the cockpit, hidden under the carpet, connected to four winches. When needed, the net can be “manually activated by the crew to lift up would be hijackers to the ceiling”. Alternatively, the machinery can, using two other winches, affix the hijackers to a wall. The patent says the whole system “can be installed on any aircraft”. Feedback hasn’t found any record of that happening yet.
A Neom ratio sighting
Reader Jason Bradbury sent in the first plausible sighting of the Neom ratio on display somewhere other than in Neom.
The Neom ratio is based on the proportions of a city planned to be built in the Tabuk region of Saudi Arabia. The city is designed to be 170,000 metres long by 200 metres wide. On 1 October, we invited you to tell us about physical objects that have that same proportion (being careful, please, to supply clear examples, and to point to documentation thereof).
Jason writes (accompanied by a spreadsheet of data): “I immediately thought of guitar strings. Using the table of guitar string gauges at , and the guide to the fret spacing of various guitar types at , I found that, of the four most common electric guitar scale lengths, only that of the Fender Stratocaster/Telecaster achieves a perfect Neom ratio for effective string length to thickness, and in three instances. With super extra light strings: open A string and G string played on the 12th fret. With medium strings: B string on the 12th fret. Sadly, those three notes make a less than pleasant sounding chord.”
Reader Andrew Forsythe sent a good example of how deceivingly difficult it can be to track down a genuine example of the Neom ratio. He writes: “I was hopeful, upon seeing a , of finding the Neom ratio. But sadly it is not even close. I’d estimate it to have a value of around 100. Too fat by a factor of 8.”
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