Derivation of the Fundamental Missile Guidance Equations
In order to guide itself to a successful target intercept, the missile must obtain inormation about the target. The prelaunch and post launch information too, must
be gathered. Before a missile is launched, that is, during the prelaunch phase, the
missile needs to know where to go. It knows that it is supposed to go to the target,
but it must be told where the target is. The missile is told where the target is by
electrical signals entering through the umbilical from the launcher. These signals
are head aimed (to point the missile head at the target), English bias (to point the
missile at the intercept point), and an estimate of true target Doppler on the simulated Doppler line.