C-Wing Optimization and Initial Results

Studies at Stanford and Boeing were undertaken as part of NASA’s Advanced Concepts Program in 1995. Concurrently, initial sizing and optimization of the original concept were pursued at NASA’s Langley Research Center.

Each of these studies involved analysis and numerical optimization of the basic concept. At Langley the FLOPS computer program was modified to handle this geometry. At Stanford and Boeing, the PASS and ACSYNT codes were also modified to analyze this design. Existing engine decks representative of modern high bypass ratio engines were used rather than estimating the performance of future technology. This represents a rather conservative approach. Additional analysis with ADP engines and laminar flow control remains to be completed, but several aspects of the design suggest that gains from such technologies may exceed those obtained with conventional designs.

The figure below illustrates example results from one of these studies with the following assumptions:

Design Mission and Constraints

Parameter       Langley         Boeing/Stanford
Range           7000 nmi	7000 nmi
Mach            0.85            0.82
Passengers       800             600 (tri-class)
Field Lengths  12000           11000
# Engines          4               3
Approach         150 kts           -

Other constraints typical of FAR Part 25.

The results indicate that substantial reductions in take-off weight are possible, even though the concept was aimed primarily at resolving some of the problems associated with very large aircraft rather than providing much better performance.