Game Development Reference
In-Depth Information
where
c
=−
4.44
e
−
7
(9.27a)
1
c
=
2.56
e
−
4
(9.27b)
2
c
=−
0.0216
(9.27c)
3
c
=
0.527
(9.27d)
4
c
=−
1.51
(9.27e)
5
A plot of the acceleration as a function of velocity curve predicted by Equation (9.26) is
shown in Figure 9-8. Also shown on the plot are the performance test measurement data points
that were used to determine the curve fit equation. Above the maximum velocity of 46.1
m/s
,
the acceleration can be set to zero. For velocities below 11.2
m/s
(the first point from the perfor-
mance test data), the acceleration can be assumed to be the same as when the velocity is 11.2
m/s
.
Figure 9-8.
Acceleration profile for the Fountain Lightning
The estimated acceleration profile shown in Figure 9-8 is not ideal. The curve is a bit steep
at the high end, so the transition to zero acceleration at
v
= 46.1
m/s
will be somewhat abrupt.
If the coefficients of Equation (9.27) were tweaked around a bit, it might be possible to flatten
the curve out a bit at the higher velocities.
The acceleration curve also doesn't account for the effects of wind or additional wave drag
(if the sea was choppy, for instance). If there were a headwind, the acceleration would be lower,
whereas a tailwind would increase the acceleration. Also keep in mind that the performance
