F-15s Looking for the AESA Edge

F-15C Eagle air superiority fighters have traditionally used APG-63 radars with mechanically steered arrays. While upgrades over the years have improved them, the mechanical steering components are a point of potential failure given the stresses put on them, and better radar technologies have appeared.

With cruise missile defense rising in importance, and longer-range detection of threats desired, upgrades are necessary. They may also correct a known air-air weakness that can reputedly be exploited by aircraft like Russia's SU-30 family. Thus far, 18 USAF F-15Cs have been modified to carry APG-63v2 radars – a misnomer, since the upgrade uses a revolutionary new technology that bears little resemblance to its predecessor.

Active Electronically-Scanned Array (AESA) radars are made of hundreds or thousands of small transmitter/receiver elements. Moving parts are eliminated; instead, subsets of their array elements are used to focus on each task very quickly and precisely, without having to move them physically, and with little signal "leakage" outside of its focused beams.

This makes it more reliable, more powerful, and able to operate multiple modes at once. There's also a maintenance advantage. A partial failure in previous radars renders them unfit for use, but AESA radars only suffer a slight performance drop if some of its TR modules fail. The fighter can still fly as it awaits a fix, enjoying all of the radar's simul-mode, range, focusing, low "leakage," and communications benefits.

AESA radars have taken a while to enter widespread service on fighter aircraft because the cost of each array had to come down to an affordable level, but once that happened their advantages become compelling.

The USAF is evaluating AESA radars for retrofit to its two-seat F-15E Strike Eagle fleet, and they've also discussed a retrofit set that would turn the F-15Cs into multi-role fighters. Meanwhile, the program to equip select F-15C units with AESA radars continues…

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