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Rutan "EZ" aircraft structural discussion

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Aircar

Well-Known Member
Joined
Feb 20, 2010
Messages
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Location
Melbourne Australia
MODERATOR NOTE: I've moved the first seven posts in this thread thread here from the "Deleted Posts" thread in the Rules of Conduct section, since it has well-diverged from that topic. The material begins below with Aircar's post, intact, answering this post by Toolbuilder, which remains in the original thread. The only edit I've made to Aircar's post here is to add this note at the beginning. - Topaz.

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Sheesh ! -- I could fill a book with professional engineers who decry Burt Rutan's approach to things (eg no wind tunnel investigation most times and debateable structural integrity from the accumulated opportunities for error etc etc --after one Vari Eze shed a winglet he found that the wing was only good for 2.5G and then imposed this 'working limit' on all other Ez's because it was (and is) impossible to test or verify the structural strength --(as in material properties plus fabrication etc ) --it is on the web and while candid is also stunning in terms of the implications (and ethics..?) Given that Burt had always said he designed in such large margins for builder variations and quoted 12Gs at one stage this is a worrying wash up . I personally concluded (in 1973 ) that it was unwise to expect first time builders to have to make primary structure without any real quality control and the avenues for getting it wrong --the foam core and 'lay up in a day' method of wing fabrication in particular --molded glass removes the vast majority of possibilities for error and avoids the drudgery of hand finishing in this example .

It depends on what you define as 'unconventional' also --in 1970 Paul Bikle said that "composite construction cannot still be said to be novel or unconventional " --42 years ago but composite homebuilders even of tractor monoplanes still try to make it seem somehow innovative (Bikle managed the X 15 program and was responsible for the building and testing of the first lifting bodies by 'clipping' various NASA Edwards budgets and getting a few homebuilders at Edwards to help Gus Brieglib (wooden glider designer builder) make the first one which was tested by towing behind a souped up buick then behind a DC 3 'unofficially' --THAT was unconventiona/,on a shoestring and truly experimental . The space Shuttle indirectly grew out of this initiative (I know about Dynasoar being sidelined etc but this work made it possible to think about flying re entry and conventional landing --the originator Dale Reed also was responsible for the ancestor to the Vari eze -mini sniffer/super snooper --these things truly justified the experimental category.

It is NOT a case of boofheads doing the unusual or unorthodox in their ignorance while the real engineers get good honest results from the tried and true (the RV4 etc ethos) and there are all sorts of examples of apparently sub adequate bits of engineering around on the most stock aircraft --if you want to lose some sleep just go through the AD updates and reflect a bit (I think it was Raymer who wrote a book about his career experiences with major failures in production aircraft and the tracing back of the underlying reasons --I have read it in a library but cannot recall the title .

Given that the 'beef' being aired on this thread was EXACTLY the 'friction' between designers wanting to do new and hence un precedented or un fully verifiable things versus the advice that does TEND to decry that basic impetus to experiment I find it a bit surprising to deny it again . I came across a Smithsonian website about "the reinventors" and an article with you tube (not viewable in Australia) about them re inventing the flying car --curious given that there is still no satisfactory flying car and it can still be said to be in the still to be invented category if compared to anything established and worked out . That is a case in point about the difference between "leave it alone -no one has succeeded at it" versus "beauty! this thing still hasn't been nailed, let's find a way !" .....
 
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