From the ultrafast F-4X to the F-4E(S): the Odyssey of Israel’s recce Phantoms

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From the ultrafast F-4X to the F-4E(S): the Odyssey of Israel's recce Phantoms
The RF-4X, also known as the RF-4ES, was a General Dynamics response to an Israeli government RFP calling for a high-speed, high-altitude photoreconnaissance platform based on the McDonnell Douglas F-4E Phantom II.

The F-4X would have featured an increase in engine thrust by 150% to allow dash speeds of Mach 3.2, cruise at Mach 2.4, and flight up to 78,000ft (23,775m) altitude

Acquired by Israel in 1969 the McDonnell Douglas F-4E Phantom II quickly became the backbone of the Israeli Air Force (IAF) thanks to its range, payload and bombing accuracy.

Along with the F-4Es the IAF ordered also several RF-4s. These aircraft were a welcome addition to the service reconnaissance assets. Their speed and range combined with their superior camera systems, allowed more complex missions to be flown with less risk to man and machine than had been possible with the Mirages and Vautours. As explained by Bill Norton in his book Air War On The Edge: A History of the Israel Air Force and its aircraft since 1947, the IAF was only the second customer for the RF-4 and these were the first to be equipped to operate with AIM-9 missiles for self-defense, employing wing pylons with twin launchers, while also retaining the bombing systems. As is common with RF-4s, the IAF recce Phantoms were equipped with the aft fuselage ejector units for photo-flash cartridges to be used during night missions. The reconnaissance aircraft were distributed among most of the F-4 squadrons.

From the ultrafast F-4X to the F-4E(S): the Odyssey of Israel's recce Phantoms
IAF F-4Es

According Norton, “during the War of Attrition recce aircraft were important assets in keeping track of the Egyptian missile boxes and locating targets for follow-up strikes. Photo reconnaissance was especially critical immediately following the War of Attrition. The cease-fire terms required that Egypt freeze its missile batteries in place, and not continue to move SAM boxes closer to the Canal. These terms were very important to Israel, and very hazardous recon flights were made to verify compliance and then monitor movement when the cease-fire terms were clearly violated. Flights into the area were made at 600kts and at such a low altitude that the major hazard was from bird strikes and hitting fishing boat masts.”

Although the IAF had ordered RF-4Es, the aircraft did not begin to arrive until February 1971 and flew their first mission on Mar. 9. To help the service accomplish this essential task, two IAF F-4Es (coded 17 and 19) were modified locally in a two-month crash program to fit a camera in the nose. By removing the gun and installing environmental and electrical modifications, either a Zeiss RMK 15/23 medium-altitude mapping camera or Fairchild KA-52 low-altitude panoramic camera could be carried. These two machines began operational missions at 69 Squadron on Mar. 24, 1970 before transitioning to 201 by September. This IAF effort may have been the source of rumors that the U.S. loaned Israel two RF-4Cs between August 1970 and March 1971 under Operation Night Light (or Peace Night Lite) for which Israel reportedly paid $143,000. They were operated by 69 Squadron during their short stay.

As Norton says “it has been suggested that Israel had a much earlier exposure to the RF-4. One source asserts that the crews and aircraft of the USAF 38th Tactical Reconnaissance Squadron were deployed from Spain to Israel – probably Hatzerim – to provide their services during the Six Day War. The RF-4Cs were supposedly given IAF markings and operated in the area until Jun. 12. While the American administration had certainly begun to lean towards the Israeli side in the Middle East conflict by 1967, this kind of material assistance during wartime was very unlikely. The IAF could certainly have used the help, freeing up their recon planes for strike missions. Another book records an even more unlikely event in 1962 when what may have been Israeli pilots collected a number of USN F-4Bs at Wheelus AB in Libya and flew them to an undisclosed location in the east. There has also been an extraordinary claim made that the U.S. Navy provided carrier landing training in the Red Sea to some 100 IAF F-4 aircrew in 1971.”

From the ultrafast F-4X to the F-4E(S): the Odyssey of Israel's recce Phantoms
F-4X configuration

It was not long before the SAM batteries were observed being moved forward. However, no one in the U.N., the U.S., or many even in Israel welcomed this news because of the possible consequences of renewed hostilities. The U.S. especially did not want anything to interfere with the scheduled Geneva peace talks. No immediate action was taken. The RF-4Es proved their worth the next summer when two, one flown by Aviem Sella, sped over southern Syria for 20min to obtain the first clear photos of mobile SA-6 batteries. Months of planning and training had gone into the mission that, because it was performed on a holiday and without top cover or ECM, went completely undisturbed by Syrians. The hazards of such missions were clear, as in October 1971 when an RF-4 returned with an SA-7 embedded in one engine. In April 1973 the IAF began high-altitude recce missions with their RF-4s, requiring the crew to wear pressure suits.

According Norton, so important was the photo intelligence generated by the IAF’s high-speed RF-4Es that the IAF sought a means of retaining this invaluable source of intelligence in the face of increasing threats to overflights of target sites. The IAF became interested in Americans’ 1,228lb (557kg) CAI KA-90 HIAC-1 ultra-long focal length (66in or 168cm) Long Range Oblique Photography (LOROP). This remarkable camera could resolve a 10in (25cm) object at 20nm range, allowing the Israelis to monitor activities near their borders without actually crossing the frontier. The Israelis made overtures to obtain one or more of the American RB-57Fs modified to carry the system. But, the U.S. rebuffed these queries.

A podded 1,500lb (680kg) version of the camera, designated the G-139, was eventually developed by General Dynamics (GD). The camera was in an enormous pod, 22ft (6.7m) long, that could accommodate 4,000lb (1,814kg) of equipment, including the associated environmental control system. In 1971 the U.S. Congress authorized export of the G-139 to Israel, and they arrived in October. The G-139 was employed on the centreline of the RF-4s and on two specially modified F-4Es. It is known to have been operated by at least 119 Squadron. How long the podded camera served is unclear.

From the ultrafast F-4X to the F-4E(S): the Odyssey of Israel's recce Phantoms
F-4X mockup

The IAF found the system very effective but the drag of the large pod degraded the Phantom’s performance to an operationally prohibitive extent. This is said to have limited maximum altitude to 50,000ft (15,240m) and maximum speed to just under Mach 1.5. Greater altitudes would permit more valuable images, but the degraded performance also placed the expensive and unique asset in grave jeopardy should an enemy attempt an intercept, and extended exposure to static anti-aircraft defenses.

Norton explains: “To answer the limitations imposed by the G-139, GD began work to boost the performance of the F-4 engines with a series of airframe modification under a program named Peace Jack. In 1971 the Israelis were invited to participate in the American effort. The Peace Jack airframe was initially to have included a radically revised inlet design and special low drag external ‘saddle’ tanks. The latter, including pumps, were to provide fluid for an engine pre-compressor cooling (PCC) water injection system to cool the intake air and increase overall engine mass flow. The two 2,500lb-capacity (1,134kg) tanks were to be mounted atop the jet, between the inlet ducts and the spine of the fuselage. These changes would, in theory, have increased engine thrust by 150% to allow dash speeds of Mach 3.2, cruise at Mach 2.4, and flight up to 78,000ft (23,775m) altitude. The conceptual aircraft was tentatively identified as the F-4X, but no actual airframe ever bore this designation.

“By 1974 a reduced size and weight LOROP camera had been designed that could be enclosed in a revised F-4 nose cavity lengthened by 12in (30.5cm) for 70ft3 (2m3) of volume. The nose included two windows on the bottom quadrant and two on either side. The entire camera could be rotated to view from any one of these windows. A separate environmental control system in the nose maintained the camera within an optimal temperature range. The design was termed the RF-4X but, again, no actual aircraft was identified with this designation. The IAF provided F-4E 69-7576 in December 1974 to General Dynamics at Fort Worth, Texas, which, over the next five months, served as the basis for a mock-up of the envisioned modifications. The combination was calculated to have allowed a Mach 2.7 cruise speed.”

From the ultrafast F-4X to the F-4E(S): the Odyssey of Israel's recce Phantoms
F-4X mockup

Up to this point, the Israelis had been financial partners in the Peace Jack effort with the USAF, but the latter eventually withdrew. The program faced at least an additional year of development, but the Israelis urgently needed an operationally HIAC capability. Alone the IAF could only afford to fund the camera installation, and the program proceeded with this goal – the saddle tanks and PCC being dropped. This design was designated the F-4E(S), with the S representing ‘Special’. The IAF had a separate KS-87 vertically mounted camera added aft of the HIAC. A number of other optical sensors could also be installed in the voluminous nose and the Air Force had no doubt developed additional packages throughout the years. A sight used to ensure that a photo target was within the oblique field of view of the cameras, was mounted on one or both of the canopy sills. Two other IAF F-4Es (69-7567 and -7570) joined 69-7576 in Fort Worth to undergo modification. First flight of the F-4E(S) was on Dec. 20, 1975 and the first of three modified aircraft was delivered on Jul. 30, 1976, the rest shortly afterwards to 199 Squadron.

While in Texas the noses of the aircraft were painted as if they still had black radome in an effort to conceal the modification. According Norton the (S) aircraft were maintained under the strictest security after returning to Israel until 1998. The type may have taken on more of an electronic warfare role late in the 1980s and ’90s, and is known to have had Elta jammers installed (the EL/L-8230 internal unit having been mentioned).

From the ultrafast F-4X to the F-4E(S): the Odyssey of Israel's recce Phantoms
Description: Israeli F-4E Phantom II (IDF designation Kurnass) with camera pod at Israeli Air Force Museum, Hatzerim airbase, Israel. 2006. Kurnass 323 is a “Toad” (or in Hebrew “Karpada”) plane, one of the planes supplied to the IDF from USAF surplus and thus kept in its original USAF green coloring scheme.

Photo credit: Lockheed Martin, Israeli Air Force and Bukvoed via Wikipedia 

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