By David A. Fulghum
Washington , Aug 13, 2010
A major sticking point on the sale by the U.S. of 84 new F-15S strike-fighters to Saudi Arabia is the degree of sophistication of the long-range aircraft’s radars.
New digital radars with active, electronically scanned array (AESA) antennas can increase surveillance and targeting ranges by three times. They can create ground maps with enough resolution to find small, moving targets. With the right software, they can become impressive electronic warfare devices. And the newest twist is that with the next generation of air-to-air missiles, they can defend against short-range and some medium-range ballistic missiles.
The original request from Saudi Arabia was for the F-15S with a Raytheon-made AESA radar that could increase the sensor’s range for detecting small targets to about 150 mi., depending on the radar cross section of the target, and almost eliminates maintenance costs. The current radar in both the F-15S and Israel’s F-15I is the manually scanned APG-70, which is no longer in production. Israeli pilots say they can see large-airliner-size targets at 150 nm., but tactical-fighter-size targets only register at about 56 nm.
The F-15Ss are part of a proposed $30-billion arms package being promoted by the Obama administration.
“I believe the Saudis want more F-15s to replace some of their older aircraft and because of the long-range [flight] capabilities of the F-15 and the upgraded avionics,” says a senior U.S. aerospace industry official with insight into the program. “They looked at other aircraft but wanted the long-range capability.”
The new AESA radar designs—such as the APG-63(v)3 on upgraded U.S. Air Force F-15Cs and Singapore’s new F-15SGs—can detect much smaller targets. The U.S. variant can find and target small, stealthy cruise missiles at ranges great enough to attack and destroy them.
More importantly, AESA radars the size of those in F-15s can find and target small moving ground targets at long range so they can be struck with standoff weapons beyond the range of antiaircraft weapons.
While Israel and Saudi Arabia carry the same radars in their F-15s, the Israeli air force has fielded long-range unmanned aircraft with precision targeting capabilities that make up for a lack of long-range radar on the manned aircraft. This gives Israel a qualitative advantage for the time being.
South Korean F-15Ks have the APG-63(v)1 (without an AESA antenna but with a digital processing back end). That means the South Koreans can upgrade the fighter’s capabilities when they can afford the advanced antenna arrays.
The negotiations and manufacturing capabilities still in place at Raytheon indicate the candidate radar for Saudi Arabia would be the APG-63(v)1 or 3. Since the Israeli air force is planning to buy about 22 AESA-radar-equipped F-35 Joint Strike Fighters, the purchase of an advanced radar by the Saudis may become a moot issue. It could also soften any onus associated with introducing a stealth fighter to the Middle East.
Fighting with insurgents along the Saudi Arabia-Yemen border reportedly has produced considerable casualties within the Saudi forces. Air raids conducted with Saudi Tornado and F-15S aircraft began late last year against Houthi rebels in the northern Yemen Sa’dah region.
It is the first military action for the Royal Saudi Air Force since 1991. Results have apparently attached some urgency to plans for upgrading air force and ground forces. After the Iraqi invasion of Kuwait in 1990, the Saudi forces were modernized, but some equipment is aging and needs replacement.
High on that list are the 82 F-15C/Ds. The Saudis’ best strike aircraft currently are 71 S-models with the Raytheon APG-70 radar with a detuned Doppler beam-sharpening capability. The Israelis have much the same radar (the APG-70I) with a similar reduction in capability. The USAF radars have about three times better resolution than those on I- and S-models. With the APG-70 radar line now closed, it is not clear which radar the new F-15S aircraft will carry.
An increasing threat in the Middle East are ballistic missiles—including Scuds—in the hands of trans-state militant groups such as Hezbollah and Hamas delivered via Iran’s Revolutionary Guard-associated Qods Force. Even long-range artillery rockets are being equipped with guidance systems that make them much more accurate, and thus a greater threat to populated areas.
Saudi Arabia, the U.S., South Korea and Japan, all operators of the F-15, are looking for a weapon to defend against aircraft-launched antiballistic missiles. Among the early candidates is Raytheon’s two-stage, Network-Centric Airborne Defense Element (Ncade) missile. It is a derivative of the AIM‑120 advanced medium-range air-to-air missile (Amraam) that is carried by most F-15s as a longer-range weapon against other aircraft and small targets like cruise missiles. Ncade prototypes launched by F-16s have shot down sounding rockets.
The combination of a large AESA radar and a powerful new air-to-air weapon would help match the Middle East’s growing short-range missile proliferation problem and help contain a nuclear weapons threat from Iran that worries planners in the region.
Right now there is a gap in missile defense because no airborne weapons can engage ballistic missiles during their boost phase from launch to low space. However, in this part of their flight, ballistic missiles are slowest and most vulnerable to attack. U.S. studies contend that air-launched, hit-to-kill missiles are operationally feasible and technically viable. The U.S. is considering making the project an urgent-procurement quantity buy.