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There may be a worse problem. The purported biological model may not exist! The following is from the in-progress second edition of my "Comparative Biomechanics..." I checked the matter with someone (who's surname I forget at the moment - Betsy something from U Mass Amherst); she has done recent work. All the figures one gets via Google Image are identical (or mirror images) of the one in D'Arcy Thompson's 1942 edition. If someone knows something I don't, there's still time (copy editing) to change my story. Steve Vogel D'Arcy Thompson (1942) suggested that the bracing of the metacarpal bone of a vulture's wing takes the form of a Warren's truss; the persuasive figure he included, from a book by Oskar Prochnow, has been repeatedly reproduced. But no contemporary study has found anything in bird long bones beyond ordinary meshworks of pillars and posts, and the excessively creative figure now appears mainly in the creationist and biomimeticist literatures. ----- Original Message ----- From: "Engineers and biologists mechanical design list" To: Cc: Sent:Tue, 21 Aug 2012 09:01:47 +0100 Subject:Welcome to the airplane of the future | SmartPlanet (courtesy of David Knight)http://www.smartplanet.com/blog/science-scope/welcome-to-the-airplane-of-the-future/13456?tag=nl.e660 [1] It's all very well talking about a fuselage designed like the struts inside a bone, but (a) the bone still has a shell, the struts are inside; (b) the bone is essentially internally triangulated. The fuselage figured in the smartplanet blog looks more like a mechanism! Are we in kingfisher/shinkansen country?? Perhaps more seriously - the wet dream of aircraft manufacturers used to be knitting the shell like a sock, extruding the structure. At least that had the possibility that the tensile elements were in the right place. What's the chances that a fuselage can be produced by RP? I haven't seen any relevant data on bird bone, but the fracture properties (production of long splinters, etc) indicate that the structure of the bone is highly orientated along the shaft. Reduction in the amount of material has to be predicated on much more careful design and analysis of loads. It's taken 25+ years (about a generation) to get carbon fibre accepted into aircraft design, and I'm told that even then the calculations are more relevant to a metal structure. Julian Vincent ------------------------------------------------Laburnum Cottage48 Frome RoadOdd DownBATHBA2 2QBtel: 01225 835076Mob: 07941 933 9013rd edition of "Structural Biomaterials" is now out: http://press.princeton.edu/titles/9774.html [2] Links: ------ [1] http://www.smartplanet.com/blog/science-scope/welcome-to-the-airplane-of-the-future/13456?tag=nl.e660 [2] http://press.princeton.edu/titles/9774.html