Download - AeroLogic

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kinematic viscosity in English units are approximately 0.00016 for feet and 0.023
for inches. See Appendix A for a listing of frequently used constants.
Some aspects of consistency of units are less obvious. Rates of rotation and
oscillation need to be adjusted to match the stated free stream velocity. For
example, in order to simulate a roll rate of 90 degrees per second in an airplane
traveling at 200 mph, while using a VINF of 1.0 in order to obtain output in
coefficient form, the roll rate must be divided by the speed in the appropriate
units. For a model sized in inches, PHIDOT would be 90 / (200 * 1.47 * 12) or
0.02551.
Similarly, if VSOUND (the speed of sound) is given its real value, then VINF must
also be a real value in order for the Mach display to have the proper units. If VINF
is 1.0, then the entry for VSOUND should be the reciprocal of the design flight
Mach number. For instance, an airplane travelling at 200 mph at 10,000 feet has
a flight Mach number of .273. If VINF is 1.0, VSOUND should be set at 1/0.273,
or 3.663, in order for the mapping of local Mach numbers to be meaningful.
Axes and rotations
A conventional coordinate system is used, with X representing the longitudinal
axis and increasing aft, Y the spanwise axis increasing to the starboard, and Z the
vertical axis increasing upward.
All rotations are performed in accordance with the right hand rule. That is, when
the right hand is held with the thumb pointing in a positive direction along an
axis of rotation, positive rotation about that axis is in the direction of curvature of
the fingers.
In the following, (R) indicates that a value is a real number, and may have a
decimal fraction component. (I) indicates an integer. (A) indicates an
alphanumeric, or text, entry.
The basic input page
The basic input page is the first section of the input file. In most cases, similar
models will be able to use similar basic input pages, with only a few numerical
changes. The most convenient way to create the basic input page is therefore to
edit an existing one.