Radar

The Su-27 carries a pulse-Doppler radar in its nose. It finds other aircraft, shows them on the left display and locks on to one for your missiles and gun.

#Switching it on

Press R, flip the RADAR switch on the MODES panel (right console), or press PWR at the top of the radar display. It takes 3 seconds to warm up before it transmits.

• It is off when you first spawn. Once on, it stays on when you respawn.
• It works on the ground too.
• Other pilots' warning receivers hear it while it's on. If you want to stay quiet, switch it off.

#The modes

#Search: RWS and TWS (BVR)

9 switches between the two. From WVR or GUN, it also switches the master mode to BVR.

The search scan is stabilised: it stays level with the horizon and pointed along your heading however you roll or pitch.

#Close combat: VS, BORE and HUD (WVR)

For a fight you can see. These modes look only 10 km ahead, fixed to the jet's nose, and lock on automatically to the first aircraft they find that isn't a friendly.

6, 7 and 8 also switch the master mode to WVR. Pressing 3 for WVR from a search mode starts in VS.

#Range, width, bars and elevation

• The range scale only changes the display: the radar sees just as far whichever scale you pick.
• A bar is one sweep across. More bars cover more height but take longer: a full ±60°, 4-bar sweep takes about 7 seconds, a ±15°, 1-bar sweep under half a second.
• Four bars cover about ±6° of height around the elevation you set. Point the elevation at where you expect the enemy to be: up for a target above you, down for one below.
• Next to the target designator, two small numbers show the highest and lowest altitudes the scan covers at that range (thousands of feet, or hundreds of metres).

#What it can see

• Looking down at a target, or at one low over the ground (under 1,500 m above it), cuts the range by a fifth, because the ground clutters the picture.
• The notch: a target flying across your line of sight, closing or opening on you at less than about 110 km/h (30 m/s), disappears, but only with the ground behind him: when he is more than 150 m below you, or less than 1,500 m above the ground. This is how pilots hide from radar. A target level with you or above you, high up, can't hide this way.
• Terrain blocks the radar. A jet behind a mountain is invisible.
• Near its maximum range the radar sees a target only now and then; within about 70% of it, every sweep.

#Locking a target

A lock points the radar at one aircraft and follows it continuously (STT, single target track). Radar missiles need it. It also points the heat-seeking missiles' seekers at the target and gives the gun its lead computing sight.

In RWS or TWS:

1. Move the target designator, the two short vertical bars on the radar display, onto a contact:
   • ; farther, . nearer, , left, / right;
   • or click the spot on the display.
2. Press Enter, or LOCK on the display's left edge. Clicking a contact directly locks it too.
3. ACQ flashes for about a third of a second, then the lock holds. Enter takes the contact nearest the designator. If the radar can't see it within about a second, the lock quietly fails: try again.

In VS, BORE or HUD: point the jet at the target. The radar locks by itself.

To unlock: press \, or UNLK on the display, or click the locked contact.

#While locked

• The radar stops searching: no new contacts appear, and the ones already on the display stay there without being updated.
• The display shows the target's range (R), closure speed (VC), aspect (0 when he points at you, 180 when you're behind him), altitude and speed.
• The HUD draws a box on the target, or a line pointing to it when it's outside the HUD.

#When the lock breaks

LOCK LOST flashes on the HUD if:

• the target goes more than 60° off your nose;
• the radar loses sight of it for 2 seconds (the notch, terrain, or too far away);
• the target is destroyed.

Changing the radar mode also drops the lock, and so does a master mode change that changes the radar (BVR from a close combat mode, WVR from a search mode); LOCK LOST flashes then too. GUN, NAV and GND keep the lock. Switching the radar off, or unlocking it yourself, drops it without a message.

#Colours