Game Development Reference
In-Depth Information
Figure 11-6.
Saturn 1B velocity profiles with and without drag
Lift
When a rocket is in flight, its longitudinal axis may be at a nonzero angle to the flight path of the
rocket. If this is the case, the rocket will experience a lift force. Usually, the lift force on a rocket
is quite small, but it does have ramifications for the stability of the rocket in flight.
Stability
Many large rockets, such as the Saturn 5 rocket that took men to the moon, are statically unstable
during ascent. Small deviations in the pitch and yaw angles of the rocket would promote larger
deviations that would eventually cause the rocket to tumble out of control. Stability of large
rockets in flight is maintained by continually adjusting the angle (called
gimbaling
) of the rocket
nozzles. If you wanted to build a really sophisticated rocket simulation, you would need to
include a stability and control model in your rocket simulation; however, the development
of such a model is beyond the scope of this topic. Less sophisticated rocket simulations can
simply assume that the rocket maintains stability during its flight.
Wind
For obvious reasons, rockets are always launched outdoors and as such may be subject to the
forces caused by any wind that may be present during launch. The effect of wind is to change
the magnitude and direction of the air velocity vector relative to the rocket. If you want to
include wind in your rocket simulation, you could incorporate wind into the drag calculations
similar to what was used when we discussed projectile wind effects in Chapter 5.
