1) An Artificial Horizon with roll and pitch information.
2) A Time-Circle, the size of which indicated the time left until the rockets were fired.
3) A gap in the time-circle indicating Range-Rate. The gap position on the circle indicated the magnitude of increasing or decresing range to the target.
4) A refference circle at the centre of the scope.
5) A Steering dot indicating the direction to fly.
The pilot had to keep the steering dot at the centre of the scope in order to follow the computed lead-collision cource, and hit the target.
A few seconds before reaching firing-distance the pilot would arm the firing cirquits by pulling the trigger. At the correct computed firing time the computer would lower the rocket-pod and fire the selected number of rockets.
When the rockets were fired the circles on the scope changed into a "X" and later into an "8" indicating collision warning and break away.
The electro-mecanical E-4 Fire-Control Computer calculated the lead-collision course and when to lower the rocket-pod and fire the rockets using the following inputs:
1) Range and Range-rate from the radar reciever.
2) Target direction angles and angle-rates from the radar antenna.
3) Roll, pitch, altitude, g-forces and temperature information from various external sensors.
All this was done using mekanical servos, syncro resolvers, rate-gyros and a lot of triode- and pentode vacuum tubes.
