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Engineering Methods in Aerodynamic Analysis and Design of Aircraft

It is left to describe the state of "Conceptual Design" and "Preliminary Design" of a
new aircraft project. As Fig. 1 outlines schematically, conceptual design is phase I
in the overall desigr process. Based on desired mission requirements, the first im-
pression of the new vehicle is achieved by using iterative design—sizing programmes
starting from existing similar "Baseline" designs with known performance. In the fol—
lowing phase II, an optimization process follows resulting in the complete definition
of the external configuration and the database for geometry, major laods, stresses
and performance. This geometric shape will be "frozen" for the detailed design (phase
III) and more sophisticated.design tools, e.g. complex Viscous CFD, will be applied.
According to the restriction to conceptual and preliminary design, contributions to
the special course have been selected. In addition to preliminary design (Chap. 2)
and. configuration finding (Chap. 3), surveys on basic potential flow' codes and
experimental verification techniques follow in Chap. 4 and 5. Due to progress in
using more and more the extended nonlinear range of angle of attack, Chap. 6 was
included, taking also account for high speed aircraft designs, having large leading
edge sweep and vortical type leading edge flow separation. The aircraft drag analysis
methods conclude this selection of fundamental surveys on engineering methods for the
daily work of the aeronautical engineer during conceptual and preliminary design in
The classical way to get confidence on a new aircraft design is the experiment using
windtunnels. This "experimental flow simulation" has led to the development of the
aircraft of today. But in recent years the extension of the flight envelope of new
projects has reached flow regimes where the flow simulation in ground test facilities
has become questionable. Too small Reynoldsnumbers, achieved in windtunnels have al—
ways been a problem, but now, in addition, the flow simulation for high speed concer—
ning temperature, "real—gas” chemistry and hot model test techniques play an impor—
tant role. So more and. more numerical flow simulation contributes to the ex—
trapolation from windtunnel to real flight data.