STRUCTURES, DESIGN
AND TEST |
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| Ever-increasing emphasis on affordability has put cost on a
par with performance for the design engineer's consideration, as evidenced in several
major aerospace programs. For example, the Shuttle's payload has been increased by at
least 500 lb (to accomplish the international space station's launch requirements) with
Thiokol's redesign of the reusable Solid Rocket Motor's new extended aft exit cone, yet
NASA's original ground rule for additional cost per pound of Shuttle payload was halved in
the process. Thiokol's design team successfully optimized performance and cost by keeping
configuration and logistics changes within the capabilities of current aft exit cone
manufacturing and shipping equipment, while still providing an increased specific impulse
of approximately 1.1 lbf-sec/lbm.
Boeing Company and General Electric have teamed on the design of the next generation of venerable 737 commercial transport. Collocated integrated product teams, replete with all business functions to influence the outcome of the product, are updating this best-selling commercial jetliner to increase range, altitude, and speed while providing owners with a 25% reduction in recurring operational costs. Knowledge-based engineering tools are also being used to capture the design engineering process, product design rules, and manufacturing criteria for components representing over half of the wing structural weight. Defense programs, formerly the bastion of "performance at all cost" development, are demonstrating their new emphasis on affordability. Currently in its second year of engineering and manufacturing development, the joint service V-22 Osprey tilt-rotor, designed and built by Bell-Boeing, |
has implemented far-ranging changes to the prototype design,
resulting in millions of dollars of cost reduction per aircraft. The aft fuselage tail
cone is manufactured using robotic tow placement in lieu of hand layup of its composite
skins, and the extensive use of high-speed machined aluminum frames and beams in the cargo
subfloor has replaced numerous costly composite parts and fasteners. May 25 was the roll-out date of the Army's RAH-66 Comanche scout attack helicopter, where design-to-cost and weight goals have been overriding considerations for the Boeing Sikorsky integrated product development teams from the beginning of this prototype development program. Extensively cocured composite subassembly designs have allowed the airframe to meet stringent cost and weight goals. First flight was scheduled for November.
AEROSPACE AMERICA / DECEMBER 1995 |
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