thanks: kreinke, ultracyclist, & ljr5487 !
[QUOTE=kreinke;277379]That has to be one of the most elegantly designed frames I've ever seen! Torsional rigidity will be the rule of the day! If there are any Motorrad engineers seeing this from the old days I bet they're saying :doh "Why didn't I think of that!"
Many reasons would complicate the use of such a frame in production. Starting with construction cost, packaging of all the components necessary for legal road use would be another, and finally, the market ÔÇô how many traditional BMW riders would be interested ? (the R1200S was introduced, and the market asked: where's the panniers ? the SO says the back seat isn't comfortable ÔÇô the model is not a big seller... Oddly, I own one).
In the late 1960's when the Type247 frame was introduced, design criteria was quite different. The demands of a 60hp engine, tire & braking technology available, and the status of knowledge regarding chassis design and dynamics formed the result. Also, in all fairness, the engineers chose as a design goal, a 'flexible' frame that would perform equally as well on ALL kinds of ROAD SURFACES, as opposed to one that would work best on the race-track. By the early '80s, BMW was looking to discontinue the Boxer, and, as a consequence, development curtailed. (remember the R1 concept ?)
I'm sure the engineers were aware of 'what could be done', and designed what best suited the 'needs' as defined by production and market demands. (although that may be optimistic ÔÇô since Udo Gietl patently rejected the special race frames provided by the BMW factory in the early '70s after a few outings, and hired Rob North to design one that actually 'worked'...)
The frame designed by Rob North and raced by Butler-Smith in the late '70s was as similar to my design as yesterday's technology allowed, and (at least superficially) quite similar at that.