Possibly used a cassegrain antenna. Elements derived from Smerch series radar. Search range 30km, tracking range 15km versus a 16 sq m target.
RP-22S was fitted to the MiG-21S, used in Soviet service only from 1965 onwards.
RP-22SM was fitted to the upgraded MiG-21SM, also not exported, and later equipped the MiG-21bis which was exported once the RP-22SM was no longer considered "sensitive".
RP-22SMA probably RP-22SM-A (version for warpac)
RP-22SMA radar operation.
The pilot controls the RP-22SMA radar with the help of switches and light-buttons placed on the block 19, 19a and 19b control panels. The control panel block 19 (on the right side of the cockpit):
Switch #1 is a three-position switch used to turn on and off the radar. In the lowest position the radar is off. In the mid position the radar is preparing for operation (3.5 – 5 min). In the top position the radar is on.After the RADAR is turned on (the switch is in the top position) a red light APCh should turn on, and off. If the light fails to turn back off, the RADAR is not operational. Aside from that, the RADAR screen should light up.
Switch #2 is a three-position switch used to control the "compensation channel" and height of the beam. In the lowest possition the RADAR works in the standard regime. In the mid position, the compensation channel is turned on. In the top position the compensation channel is turned on, and the lower border of the scaning beam is lifted by +1.5 to +2deg over the horizon (this mode is reserved for low altitude intercepts).
Switch #3 is a two-position switch, which controls the "locked beam" mode. In the lower position the "locked beam" mode is off. In the upper position the beam is locked in 0 deg in azimuth and –1.5 deg in elevation. A green light over the switch signals this. This mode is used for launching Kh-66 beamriding radar guided missiles against ground targets.
This panel is located directly over the radar scope. On it, there are red light-buttons (if a button is pressed it lights up). Turning the light-button controls the brightness (The pic shows maximum brightness)
Button 1 – "interrogate" – turns on the IFF system
Button 2 – "msc" – turns on the "speed selection" mode used to attack low speed targets
Button 3 – "control" – automatic testing of the whole set
Button 4 – "break-lock" – breaks a lock and returns to scan mode
Button 5 – "meteo" – turns on the mode for compensating for difficult weather conditions
Button 6 – "pass" – anti-passive jamming mode
Buttons 7 and 8 – more anti-jamming modes
Panel 19b is only used in wartime. (No info)
In the search mode, the radar scans +-28 degrees in azimuth and +-17 deg 40 min in elevation. Max range is 30km. The radar display shows the range and azimuth of the target. With the help of "higher" and "lower" marks, in pitch ranging from –25 to +8 degrees, it displays the altitude difference. The display also shows the IFF status of the contact. Search mode gates the target before lock.
The RP-22 scope in scan mode
1. Friendly target (if the IFF is on)
2. Foe target (if the IFF is on)
3. A target below our plane
4. Gate. It is controled by the pilot, using a switch on the throttle. The target has to be between the two horizontal lines to be locked
5. A target above our plane
6. A target on the same altitude
9. This light is on, when the RADAR is working in track mode, in active jamming conditions
10. Red light, which warns if the RADAR is inoperational. It (RP-22) has to be turned off immediately if so
This is an ideal situation. In normal conditions there are dozens of smaller and bigger bright dots, and a couple of false targets (clouds, etc.). A pilot has to guess which target is the real one, utilising information from the navigator and different onboard devices. On the 1st pic the target is 10km away. On the second one, it is 5km away, and the pilot should be able to get a lock. To do that, he must press a button on the stick.
In the intercept (automatic track) mode, the scope displays the azimuth and elevation of the target, the range, the allowed launch zone, and calculates the range of the break-away.
RADAR scope in track mode.
1. The range of azimuths allowed in the intercept
2. Range markers
3. Minimum allowed launch range
4. Aiming mark
5. Aiming ring
6. Max allowed launch range
7. "Seeker ready" light. This light is on, and the pilot hears a tone in the headphones when the missile has locked on the target 8. "Launch" light. Optimal launch conditions have been met. The pilot may launch
9. "Breakaway" light – the pilot must immediately break the attack.
When using the LAZUR automatic guidance system, the three lights indicated give the direction to target. In the picture, the target it to the right (light #3 is on). Light number #1 indicates the target is on the left, and light #2 that the target is directly in front of us.