LXNAV S10 Series, Руководство пользователя

Страница: 88 / 121

Rev #37
Version 8.0 April 2021
Page 88 of 121
We assume that the wind vector comprises two elements: a slowly varying component and a
rapidly varying random disturbance. Next figure shows that the more turbulent the air mass,
the greater the random increment is. The three wind components are assumed to be
independent of each other. All three obey the same mathematical law.
The perspective representation of a three-dimensional vector on the display does not make
sense for gliders. Glider pilots are used to reading the vertical component of the vector on
the Vario and interpreting the x-y components as “wind”.
Time behaviour of the wind field
d
(
x, y, z
;
t
) .
For an intuitive understanding of the model, we limit ourselves to the vertical component.
We are used to interpreting the rate of the variometer by the movements of the pointer. For
this reason, we look at the increment over a time interval of 1 second.
In picture above, the variometer shows a value of 3m/s. This value corresponds to the slowly
changing part of the model. The rapidly changing, random part corresponds to the
fluctuations of the pointer around the mean. The pointer fluctuations are Gauss- distributed,
see right picture above. The Standard Deviation parameter,
σ
d
determines how likely an
increment is around the mean of 3 m/s. For example,
σ
d
= 1 m/s states that 68% of all