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Old Dec 16, 2013, 05:10 PM
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We've looked at this sketch before, but it shows the nature of Spirit's spar configuration. One of the more important aspects of construction leading directly to successfully making the Atlantic hop.

Note the tapered top and bottom spar caps of rather complex fitting and spicing of various thicknesses etc, over the semi-span of wing.. The overall outside spar dimensions, once maximized, did not change. The interior did, being thickest at strut attcment point. Normally a spar's max ht determined by the aperture in the ribs, defined by top and bottom rib caps, where they pass ove rrthe spar. The aperture for the Spirit's spars were MAXIMIZED FURTHER by actually cutting into the top and bottom rib cap strips until ony 1/8" of the original 1/2H x1/4"W cap stock remained (!!) to pass over/under the spars.

This arrangement of tapered spar caps construction is clarified in Hall's post flight drawing for NYP2 spars, found in the files of Posey Bros of. Washinton State. Posey Bros. specialized in supplying spruce to the aircraft industry, sub-contracting spars for many different manufacturers. It is not clear if they ever did produce "assembled component" spars for Ryan.

Jack Northrop is credited with an improved spar design, that saw introduction prior to Spirit.. It is possible we are looking at a Hall maximized version of earlier basic design and still able to utilize the standard, but scarily modified M-1 rib.
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Old Jan 16, 2014, 11:31 PM
UMs & parkflyers... for now.
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Ryan NYP Spirit of St. Louis

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