vdryd1.hlp

MATLAB在飞行动力学和控制中应用的工具

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VDRYD1 = Lateral Dryden filter #1. This masked subsystem block
which is contained in the library WINDLIB from the subdirectory
WIND, implements a lateral Dryden filter with constant coeffi-
cients. The user must specify the scale lenght Lvg, the standard
deviation sigma_vg and the airspeed V. In reality, V will not be
constant, but often, the resulting changes in the filter coeffi-
cients may be neglected, without affecting the resulting gust
velocities very much. Use the block VDRYD2 if the airspeed varies
so much that the filter coefficients cannot be held constant any-
more (see VDRYD2.HLP for more info).

The lateral gust velocity vg is obtained by passing white noise
through a Dryden filter, which is defined by the following trans-
fer function:

            b0 + b1*s        a0 = (V/Lvg)^2
  Hvg = -----------------    a1 = 2*(V/Lvg)
         s^2 + a1*s + a0     b0 = sigma_vg*sqrt(Lvg/V)*(V/Lvg)^2
                             b1 = sigma_vg*sqrt(3*Lvg/V)*(V/Lvg)
where:

  V       : true airspeed [m/s]
  sigma_vg: standard deviation of lateral gust velocity [m/s]
  Lvg     : scale length for lateral gust [m]

Here, V is pre-specified by the user in one of the dialog-boxes
of the subsystem VDRYD1.

Outputs from the block VDRYD1:
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  vg      : lateral gust velocity [m/s]
  d(vg)/dt: time derivative of vg [m/s^2]

The block VDRYD1 has no inputs.

The gust velocity and its time derivative have to be added to the
total wind velocity component vw and its time derivative vwdot in
the vector uwind.

More info.
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See UDRYD1.HLP, WDRYD1.HLP, and TURB1.HLP for more info about
other Dryden filters with constant coefficients. See UDRYD2.HLP,
VDRYD2.HLP, WDRYD2.HLP, and TURB2.HLP for more info about Dryden
filters with coefficients that vary with the airspeed V.

See CWIND.HLP and BLWIND.HLP for more information about blocks
to compute the components of wind along the aircraft's body-axes
(constant wind and a wind profile in the Earth's boundary layer,
respectively). The use of the vector uwind within the aircraft
model is outlined in the helpfiles LEVEL1.HLP, FWIND.HLP, and
XYHDOT.HLP, which refer to blocks within the system BEAVER.

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The FDC toolbox, Copyright Marc Rauw 1994-1998.