Israel’s radar-busting Shermans

The M4 Sherman was the main American tank type of WWII. After the war, it saw additional combat worldwide – first as a tank in its original WWII form, then in following decades through various upgrades, and in rebuilt form for non-tank uses.

One of the more remarkable of the latter was the Kilshon, an Israeli system to destroy the radars controlling and guiding enemy surface-to-air missiles (SAMs).

m4

(US Army M4 Sherman tank in action during WWII.)

main

(The Israeli Kilshon ARM launch vehicle, which used a WWII Sherman as the lower portion.)

An ARM (anti-radiation missile) is a weapon which homes in on enemy radars. Along with ECM (electronic countermeasures, or jamming), ARMs are the cornerstone of what is today called SEAD – Suppression Of Enemy Air Defenses; the total tactical concept for crippling a foe’s anti-aircraft defenses.

the Sherman

Little introduction is probably needed for the M4 Sherman. Now 75+ years after WWII, it remains one of the most recognized items of the war with the general public, and probably the best-known American tank ever.

m4ford

(Sherman tanks being built by Ford during WWII.)

origins of SEAD during WWII

During the Allied bombing campaign against Germany, a variety of ECM were used against the Reich’s anti-aircraft defenses. The simplest and most common was chaff. This was (and still is, today in the 21st century) strips of metal foil ejected from a warplane to temporarily blot out radar with thousands of false returns. Another idea was the RAF’s Airborne Cigar project, which disrupted the Luftwaffe’s GCI (ground-control intercept) radio network between air defense radars on the ground and fighters in the sky.

The United States considered that instead of temporarily blinding German radars, it would be better to somehow directly target and physically destroy them. This seems logical today but during WWII, it was borderline science fiction. Using crude early-1940s analog electronics then available, any weapon with any sort of internal guidance of any type was quite remarkable. A new piece of air-dropped ordnance with completely autonomous operation, homing on enemy frequency bands, probably seemed impossible.

mothharvard

(The Moth was to be based on the Mk7 Pelican glide bomb. This weapon’s development was cancelled late in WWII as technology had already passed it by.)

A joint team between Harvard University and the National Bureau of Standards developed the Moth ARM, a powered version of the Mk7 Pelican the US Navy was working on during the middle part of WWII. The Moth project bounced from the US Navy to US Army, and in the final concept was a powered winged bomb to be dropped against German ground radars. Development lapsed after Germany surrendered in May 1945 and was altogether abandoned when WWII ended four months later. Moth was never deployed and as far as is known, never even fully tested.

Japan studied the I-Go Model 1 Hei, a SEAD missile with a microphone in the nose. It was tuned to home in on the distinctive report of US Navy Mk2 and Mk4 40mm shipboard anti-aircraft guns. This work is sometimes confused today with the unrelated Yuuji Shinkan project, which was a failed effort to fit a microphone fuze to an air-to-air bomb (aka “aerial mine”), that would detonate when the sound of a B-29’s engines passed close by.

This sound-homing SEAD weapon was developed by Tokyo Imperial University in early 1945, based on the I-Go anti-ship missile. Japan completed 150 of those by WWII’s end but never employed them in combat. Regarding the acoustic weapon, development was cancelled mid-1945 as it required twin-engined Ki-48 “Lily” or Ki-102 “Randy” planes to test-fire and Japan was desperately trying to conserve aviation fuel by then.

This unusual acoustic SEAD concept was perhaps sparked by the Type 97, a microphone device which the Imperial Japanese Army used to remotely locate Chinese howitzers, surprisingly with some occasional success. After WWII, the US Navy was made aware of the sound-homing SEAD project, and concluded it would have never worked even if development had continued.

the road to Shrike after WWII

SEAD development was fully halted by budget cuts the American military underwent after Japan’s surrender.

bat

(A WWII TBM Avenger armed with a Bat anti-ship missile. During WWII the missile was typically employed by twin-engined or four-engined types but the Avenger torpedo plane, Corsair fighter, and Helldiver dive bomber were also compatible.)

When the Korean War started in 1950, it was once again determined that an ARM was needed. During WWII’s final months the US Navy used some ASM-N-2 Bat guided missiles against Japanese ships. Of the roughly 3,000 Bats made during WWII, many were still warehoused in 1950 and it was attempted to rebuild them into an ARM, known as Bat II. The old WWII weapon was not really a suitable foundation and a reliable anti-radar seeker was not perfected.

After the Korean War, development of the US Navy’s Corvus began. This ARM cobbled together parts of Bat II with new technology. It was fitted with a 10kT nuclear warhead; about half the yield of the Nagasaki bomb during WWII. It was intended to home against the air traffic control radar of an enemy airbase; then taking out the radar, hangars, parked warplanes, the control tower, the runway, pilot’s barracks, and any AA defenses all in one shot.

corvusExBat21950s

(Corvus aboard a US Navy aircraft carrier.)

Obviously the biggest problem with Corvus was that it would be unusable in a conventional-only war. It was also extremely expensive and still had design bugs. It finished development in 1959 – 1960 and was set for low-scale production, but was cancelled later in 1960.

In 1959 the US Navy started a project, codenamed “Cobra”, for a more tactically usable and affordable SEAD weapon. The Cobra was a 8″-diameter airframe using a Corvus seeker and the AIM-9 Sidewinder’s control mechanism, powered by a quad-pack of rocket motors based on the FFARs and HVARs of WWII.

cobra1959

(Cobra test missile in 1959.)

Cobra was not an immediate success but was good enough to convince Congress that a workable ARM, elusive since WWII, was now finally within reach. With that, more funding was secured.

In 1961 the Cobra project was redesignated AGM-45 Shrike. It was advantageous to adapt the project to the airframe of the AIM-7 Sparrow air-to-air missile, which was also 8″ in diameter and already cleared for existing underwing pylons. This was paired with a new seeker, a new warhead, and a new rocket motor; all developed specifically for the ARM mission. The final product was approved for production in 1965.

AGM-45 Shrike

The Shrike was 10′ long, 8″ in diameter, with a 1’6″ finspan. It was powered by a single-stage solid-fueled rocket and flew at Mach 1.5.

shrik

To fire a Shrike, the carrying warplane aligned itself down the bearing of the enemy radar, which had to be transmitting at the time. A “nose dip” maneuver oriented the Shrike in the up/down direction. After this, the plane went into a steep climb, firing the Shrike mid-climb (effectively “lobbing” it, adding some range), then finishing an Immelmann maneuver (a vertical u-turn to leave the area). The “dip” maneuver was mandatory, the lob was not, and the Shrike could be fired in a dive if desired. After firing, the Shrike was already locked on and no further action was needed by the plane’s pilot.

The warhead was 149 lbs of pour-cast high explosive, lined by 22,000 3/16″ cubical pellet-like fragments. Compared to the design of WWII HE-Frag bombs, a lot of study and effort was put into the Shrike’s warhead pellets; as to how they dispersed upon detonation and in what pattern.

shriketest

(Near-miss of a Shrike on a generic target transmitter during a 1987 exercise with a F-16 Falcon fighter.)

The fragments shot out in a 70° fan pattern. Their speed varied somewhat; many would impact the target at extremely high velocities; others slightly less causing more “blunt” damage. There was also a blast wave. It was not necessary for the Shrike to directly impact the radar to destroy it.

22kpellets

(Effect of a Shrike near-miss on an American emulator of the Soviet “Fire Can” gunnery radar.)

The fragments had a wide range and it was intended that besides the actual radar being targeted; things like its electric generator trailer, towing truck, crew tents, offboard radio antenna, and so on might be damaged too. The weapon detonated still several feet off the ground and some of the pellets projected on a downwards angle, where umbilical cables might be laying. The intent was as much not just to totally obliterate one thing but to also cause time-consuming damage to many things nearby.

sa3goaAusairpower

(A typical SA-3 “Goa” SAM battery of an Arab army. In the center is the SNR-125 “Low Blow” guidance radar and with it the battery command cabin, towed electric generator, flatbed, support gear, and umbilical cables in its shared revetment. A Shrike hit on the transmitter might damage all of these as well. The three missile launchers in their separate revetments would be protected.) (photo via ausairpower website)

Shrike was first used in combat during the Vietnam War, starting in 1966, only a year after it began production. The initial 1965 AGM-45A version was limited to 10 miles and had numerous problems. The AGM-45B version, which appeared at the decade’s end, increased this to 25 miles and eliminated many of the bugs.

seeker

(The internal anti-radiation seeker of the Shrike, with its spiral antenna inside a dielectric retainer.)

Like any weapon, Shrike was not perfect. The main flaw is that it lacked a memory. If the targeted radar stopped transmitting after the Shrike was fired, the missile broke lock and just flew “dumb” until it ran out of fuel and crashed.

Another issue was that each was hardwired against a specific Soviet-made radar. On the missile, this was noted by a numerical suffix, for example AGM-45B-2 could only be used against the SNR-75 “Fan Song” SAM guidance radar, while AGM-45B-7 only against the P-15 “Flat Face” early-warning radar, and so on. This meant that squadrons had to keep a variety of missiles on hand, and had to know what the target would be before the plane took off.

None the less, by late 1960s standards, Shrike was a tremendous asset to the United States, finally filling the niche envisioned during WWII.

Shrikes to Israel

The USA was initially very reluctant to export this new technology. It was a completely new form of warfare, and an overtly offensive weapon.

upiMarch1970

(This map is from a March 1970 UPI media packet and illustrated a recent air raid against two Egyptian (United Arab Republic as it was then known) radar sites across the closed Suez Canal. Prior to obtaining ARMs the Israelis attacked these with brute force, flying extremely low to hopefully approach the radars beneath their lower limit and then trying to hit them at point-blank range with free-fall bombs. This was, naturally, very risky.)

In late 1970 the USA agreed to a limited export of Shrikes to Israel, capped at 100 missiles, with deliveries starting in 1971. These were all AGM-45As; the shorter-ranged, less-reliable early model. The IAF (Israeli air force) assigned them to A-4 Skyhawk jets.

shrike

The first use was during the “war of attrition”, the skirmishes inbetween the Six-Day War and the Yom Kippur War. On 18 September 1971, a dozen AGM-45A Shrikes were fired by A-4s across the Suez Canal at Egyptian radars associated with SAM launchers. Only one of the twelve hit and it did not fully destroy the radar.

start of the idea: land-based Shrikes and WWII vehicles

An ARM-firing sortie was not risk-free. A typical SAM of the Arab forces, the Soviet-made SA-2 “Guideline” itself had a range equal to or greater than the Shrike. The firing plane also risked getting bushwhacked, where it would detect one SAM-guidance radar and mount an attack, but then a second SAM guidance radar from a different direction would come on line to target it. Finally the Shrike-carrying plane still risked getting bounced by enemy fighters.

For a small country like Israel with limited resources, the loss of even one trained combat pilot is a big deal. Therefore it was attractive to find an alternative way to use Shrike against enemy radars, especially Egypt’s formidable assortment.

Prior to the 1973 Yom Kippur War, the Israelis constructed the Bar Lev Line, a string of 22 firebases in the occupied Sinai peninsula along the east bank of the closed Suez Canal. Directly on the Canal a 60′ sand berm was made, topped by barbed wire. About 100′ – 300′ behind that were the firebases which housed an infantry platoon along with machine gun positions, mortars, and light artillery. Slightly behind them were two north-south roads, the Lexicon Road which linked the firebases together and the Artillery Road, which was more amenable to moving trucks, tanks, and towed artillery. Even further behind it was the Supply Road, a final north-south path that linked into east-west roads towards Israel.

On the other side the Egyptians were steadily inching their radars and SAMs closer and closer to their bank of the closed Canal. This was logical as every thousand yards eastward allowed the radars to look another mile or two deeper into the Israeli-occupied peninsula, and fire SAMs at any approaching Israeli jets before they even crossed the Canal.

barlev

(An Israeli soldier in the occupied Sinai peninsula looks across the Suez Canal. This was atop the sand berm; the firebases were usually about 100′ or so behind it.)

The IAF decided to develop a method of ground-firing Shrikes against the Egyptian radars across the Canal, from the roads of the Bar Lev Line. Work on this started shortly before the 1973 Yom Kippur War. The project’s name was Potifar.

POTIFAR

Work on this system started and was perhaps even completed, or close to it, by the time of the October 1973 Yom Kippur War but it was not fielded during that conflict.

The vehicular mount chosen was a WWII American half-track, the M3. During WWII half-tracks proved quite useful to several armies, the USA being one of them. The advantage was that compared to a fully tracked vehicle, they were cheaper and quicker to build. Each cost $10,310 or $150,671 in 2021 dollars. They steered like an automobile and the M3 in particular was easy; any GI with a civilian drivers license could master it in a few days. This compared well to fully tracked tanks, which had specialized driving training. Half-tracks retained some (but not all) of the cross-country mobility of a fully tracked tank and had highway speed (45mph) similar to a wheeled truck.

M3-Halftrack

(US Army M3 during WWII.)

The M3 of WWII weighed 10 tons and was 20’3″ long. It had the driver and a passenger in the cab, and a dozen soldiers in the rear. It was very lightly armored (¼” – ½” at most, in some areas even less and with the top completely open). It was not really intended for direct combat although during WWII it often found itself in such. Tens of thousands were built during WWII.

There was nothing inherently flawed with the concept but after WWII, half-tracks faded away as new military trends turned to a split between either fully tracked APCs, or all-wheel drive armored vehicles.

Israel used WWII American half-tracks heavily, starting in the late 1940s and then in every major war afterwards. The Israeli army favors dynamic fast engagements and for this, whatever their limited armor, the WWII half-tracks were very ideal. Israel imported not only the basic M3 but also the smaller M2, the M5 International Harvester-production version, and the M9 which were intended for Lend-Lease. Israel designated them all as “M3″s, whatever their actual WWII lineage.

Besides their intended role, the Israeli M3s were adapted to many new uses, at least two dozen different modifications being known. Before the Potifar project, some of these involved missiles.

24854544

(WWII M3s were the intended mount of the Luz surface-to-surface missile of the 1960s. In the end, Luz was judged too expensive and not fielded.)

ssmisiles3

(Israel rebuilt some WWII M3s as modern tank destroyers, carrying SS.11 wire-guided missiles. These were indeed fielded and used in active combat.)

For Potifar, a basic stock M3 had its onboard machine gun and passenger area removed, with the area behind the cab cut down to the chassis. A twin launcher for Shrikes was installed, fixed in bearing but adjustable in elevation. The work was done by Israeli Aircraft Industry’s Mabat factory.

potifar

The WWII half-track was simply a carrier for the launcher. It was not intended that the vehicle travel with Shrikes on the launcher, in fact, the M3 was basically immobilized with a missile mounted. A separate truck would be assigned to carry missiles to the launch site and load them once the M3 was positioned.

Gen. Benny Peled, who was at the time the commander of the IAF, was interested in the Potifar project. During Israel’s war of independence in 1948, Peled was a mechanic for Avia S.199s, the Czechoslovak-made half-clone of WWII Germany’s Bf-109 fighter. Later he was the first Israeli pilot to use an ejection seat. Peled was open to new or unusual ideas, and ensured the Potifar project got funding.

a target-rich environment

While Potifar was being considered, ground-firing ARMs from WWII vehicles in the occupied Sinai across the Suez Canal seemed like an idea with promise.

Egypt’s Abu Suweir airbase is located 11 miles west of Ismailia and about 12 miles away from the Suez Canal. During WWII, it was known as RAF Abu Sueir and housed a British squadron of Wellington medium bombers fighting the German Afrika Korps, and later in WWII an American B-24 Liberator strategic bomber unit. After WWII, a Meteor squadron was based here. Because of deteriorating diplomatic relations between the UK and Egypt, the RAF handed the base over to Egypt on 14 April 1956.

ww2

(RAF Abu Sueir during WWII on the left, and on the right Abu Suweir during the mid-1950s as it was turned over to Egypt; having been enlarged and paved to fly jets.)

In the early 1970s Abu Suweir housed modern MiG and Sukhoi jets but was also the GHQ of one of Egypt’s four air defense zones. The desert around the base and eastwards in the 12 miles towards the Suez Canal was plastered with radars and SAM sites.

egyptiansa2

(Egyptian SA-2 “Guideline” SAM reload bearer in front of a launch rail.)

a failed system

Potifar was not a success. For one, it was just completing its final development when the Yom Kippur War began on 6 October 1973. The Egyptian operation “Badr”, the cross-Canal assault to open the war, was masterful and a complete success. The Israelis estimated it would take at least half a day just to breach the sand berm, if an Egyptian force made it across at all. Instead, Egyptian sappers used high-pressure water pumps to gouge holes through the sand berm. Only 180 minutes after the war started, Egyptian forces had not only breached the berm but overran one of the Bar Lev Line firebases.

Using pontoon bridges, the Egyptians established three bridgeheads on the Sinai side by 7 October, then another three by 11 October, then another two by the 13th including ones now south of Great Bitter Lake. The Bar Lev Line had been a failure. The Egyptian advance into the Sinai peninsula petered out as they passed the air-protective umbrella of their SAMs on the African side of the Canal. The Israelis pushed the Egyptians back and by the short war’s end on 23 October 1973, had themselves crossed the Canal and held a small bridgehead on the African side, marooning Egypt’s entire III Army Corps in the Sinai desert.

30oct1973

(The Israeli flag flying again on the Bar Lev Line’s berm on 30 October, where the war had started a few weeks earlier. The WWII M3 half-tracks are TCM-20 conversions, which replaced the WWII crew area with two HS404 20mm autocannons. Intended as mobile air defense, in 1973 these were more useful in the anti-infantry role against Egyptian AT-3 “Sagger” wire-guided missile gunners.)

This course of events would have prevented Potifar from being used, even if it had been ready. But this would not have really mattered as the weapon itself was not a success.

The M3 half-track was no problem, and there were no issues integrating the modern Shrike with the WWII chassis.

The problem was the AGM-45A Shrike itself when used in this way. The early-version AGM-45A had a 10 mile range when fired off a combat jet, as intended. Here, the missile would already “start” inherently with whatever speed the warplane was flying when it was fired, and would fly a downwards angle of some slope all the way assisted by gravity.

With Potifar, the Shrike would start at 0′ altitude and 0 kts airspeed. This meant that the rocket motor would expend some of its potential energy just getting the missile to the apogee of its flight arc. The Israeli design team was not foolish and realized this, and estimated that the range would be cut from 10 miles to 6¾ miles at best.

What was not immediately recognized is that the Shrike would “atmospheric transition” not once, but twice. Instead of going from cooler, lower-density air downwards to warmer denser air as altitude decreased, instead it would go through this cycle twice. This meant it could not fly a true arc, wasting more energy.

While a 6¾ miles range was apparently achieved at some point during the development, a more realistic maximum was felt to be between 5¼ – 5¾ miles.

The closest the Potifar launchers could have gotten on the occupied Sinai would have been the Bar Lev Line’s Artillery Road, which was set back between 155′ – 400′ from the berm along the Suez Canal’s east bank. The waterway itself was at that time between 310′ – 485′ wide, in some areas with passing lanes, 524′. All this meant that the missile would waste between a sixth to a quarter of a mile before it even began passing over Egyptian-held territory.

After Anwar Sadat made his mind up for another war sometime earlier in 1973, the Egyptians continued inching radars and SAMs closer to the Canal. By late 1973 they were, in some places, only about 1½ – 2 miles away. But obviously the Egyptians were not going to put extremely expensive, “soft” things right up on the bank. Mostly, 3 to 3¾ miles was the closest as this kept them out of range of the light artillery in the Bar Lev Line’s firebases. Many were even further back.

egyptianfansong

(An Egyptian “Fan Song”. This was the guidance radar for the SA-2 “Guideline” SAM. Actually a combination of several radars, it had the two planar antennas (one vertical, another horizontal), two narrow-beam tracking dishes, and an offset transmitter dish to communicate with inflight “Guideline”s. One “Fan Song” could serve a half-dozen SA-2 launchers.)

The final sum of all these distances was that, from firing off the Artillery Road towards the realistic locations of Egyptian radars, Potifar could have only targeted a usable slice of Egypt 122 miles long north-south, but only between 4,800yds – 5,300yds wide east-west. There was little practical value to this.

An unrelated problem was that the AGM-45A had to be aligned with the targeted radar no more than ±3° off-axis when fired. On a warplane this was no problem, the pilot just tapped the rudder a bit until the plane’s nose lined up. But with Potifar, the launch vehicle had to correlate its fixed parked position with reconnaissance maps of where the targeted radar was at. The Artillery Road was not a well-mapped highway, but a hastily-built military road. It was predicted that Potifar might have issues knowing exactly where it was at when fired.

Potifar was abandoned several months after the end of the Yom Kippur War. The number built is unknown, most Israeli sources say “two launchers” but it is unclear if that means the twin launcher on one M3 or two converted WWII half-tracks.

This was by no means the end of the basic M3’s Israeli service. They were in frontline use until 1987 and the final WWII half-track did not leave the Israeli army until 1999.

takenout1999

the interim

Shortly after the Yom Kippur War, Gen. Peled was in the Golan Heights looking towards Syria and expressed a wish that there was a way by which he could “push a button” to engage Syria’s air defense network. So although even Potifar was a failure, the concept was still alive within the Israeli military.

Several things that happened during and after the Yom Kippur War would influence how the idea moved forward, and to what WWII vehicle it would be paired with.

The first was the Shrike itself. During the conflict the USA had, as part of operation “Nickel Grass” (the emergency resupply of Israel with ammunition and weapons) delivered later-model AGM-45Bs with increased range. These were in many cases yanked from USAF units on NATO bases in Europe and flown straight to IAF squadrons in Israel for use. The United States also opened up this version for purchase to Israel, and eventually 300+ of the AGM-45B version were delivered.

The second was Israel’s strategic situation after the war. Even though the Israelis had pushed the Egyptians back to the Suez Canal (and briefly themselves crossed it), afterwards both nations decided on a “disengagement”. Instead of Egyptian and Israeli troops again directly staring at one another across the narrow waterway, Israel pulled back to a line deeper in the occupied Sinai while the Egyptian army did not move into the vacated zone, creating a buffer. With that, there was no possibility of using a ground-fired ARM in the south, as Egypt’s air defense network was now way out of range. So attention turned north towards Syria.

During the 1973 Yom Kippur War, Israel’s upgraded M4 Sherman versions had performed decently enough but during the war, the Arab armies used T-54/55s and T-62s and it was expected that they would soon have T-72s. Unavoidably this WWII tank’s place on the battlefield would be coming to a close. So there were a lot of recently-upgraded Israeli Sherman hulls that could be dipped into for other uses.

KILSHON

Using the later-model AGM-45B Shrike as a starting point, work began in late 1973 on a longer-ranged system mounted on an upgraded Sherman hull.

the M4 Sherman in Israel

The story of Israel’s long use of the WWII Sherman is outside the scope of this writing and itself could fill a book. (Indeed several have been written on the topic.) The first Israeli Sherman was a WWII derelict found in a shed as the British were departing. These were joined by a buy of junked, gunless Sherman hulls from a WWII scrapyard in Italy re-armed in Israel during 1948, and then later still other buys from as far away as the Philippines.

earlysherman

(M4 Sherman in the early Israeli Defense Forces.)

Shermans were kept current by a series of upgrades. The M-1 Super Sherman (which is commonly a nickname to any of the upgrades) was a M4A1 armed with a 76mm main gun and HVSS suspension replacing the original vertical volute design. The M-50 was any WWII Sherman rebuilt with a turret counterweight, French CN 75-50 main 75mm gun, Cummins diesel engine, and HVSS. The M-51 Ishirman was the most dramatic upgrade. It had a Modéle F1 modified 105mm main gun along with every possible earlier improvement.

m1inYKwarCIA

(M-1 Super Sherman early upgrade.)

As Israel upgraded its Sherman fleet, WWII hulls were also adapted for other non-tank uses including self-propelled artillery, armored ambulance, and so on.

MAR240

(The MAR-240 was an idea to mate the Sherman hull with a launcher for Soviet-made BM-24 rockets, of which the Israelis had captured huge numbers and also reverse-engineered. Although a success it was not selected for mass production.)

Israel definitely had experience with converting Shermans to non-tank uses, and the technological skill to proceed with further such projects. For the Kilshon (pitchfork in Hebrew) project, the Sherman selected was the M-50 upgrade.

m50sla

(M-50 rebuilt Sherman)

The M-50 upgrade removed whatever WWII engine was in the Sherman and replaced it with a 460hp Cummins V-8 diesel powerpack. Some (but not all) had the bow M1919A4 machine gun removed. During WWII this fifth position had been a “co-driver”, a replacement crewman if needed and an assistant to getting the Sherman started, which in its WWII form was not a turn-key affair. He also operated the second radio. The bow MG had a limited field of fire and new radios made his other duties redundant. The Israelis sometimes removed the machine gun and filled the seat with sandbags as extra protection.

The M-50 shown above served in the South Lebanon Army, Israel’s allied proxy force to the north. On 18 April 1979 Saad Haddad, a rogue major in the Lebanese army, created a tiny self-styled statelet in southern Lebanon between the Litani river and the Israeli border. The SLA was equipped entirely with Israeli-supplied weapons or captured Arab weaponry (note the AK-47 on the glacis armor). Unrecognized outside of Israel, this mini-nation was officially called the Free State but was dismissed as “Haddadland” by the skeptical world media. None the less, SLA troops fought tenaciously and were a force to be reckoned with on the battlefield. Haddad passed away in 1984 and the SLA collapsed in 2000.

Kilshon: automotive components

palbaDotcz

(Kilshon ARM vehicle with the travel brace lowered.) (photo via palba.cz website)

All of the combat improvements in the M-50 upgrade were irrelevant as the whole turret was obviously removed. Besides the modern Cummins diesel engine, the vertical volute suspension system was replaced by a HVSS system.

suspension

(HVSS on a Kilshon. By best estimate this much-altered and twice-rebuilt tank had at one point been a WWII M4A1.)

HVSS uses two horizontally-oriented strips of spring steel wrapped into a conical coil, attached to a roadwheel and pushing against each other, on a common bogie. This is better than a vertically-oriented spring on a bogie attached to two wheels. Designed in the latter part of WWII, the Sherman’s HVSS was intended to be substituted with no modifications needed to the basic construction plan of the tank hull. A byproduct of this was that after WWII it was a relatively easy “bolt on” improvement. Of tanks were rebuilt during the M-50 project, some already had HVSS from WWII so even this step was not always needed.

The remainder of the hull remained largely true to the original WWII design of the Sherman.

front

(The front of a Kilshon.)

The rectangular frame held a small cargo box which would have completely blocked the bow M1919, which was almost certainly omitted from the vehicle as the Kilshon was not intended to ever see direct land combat. The white light headlight next to the MG portal always had a hood on M-50s, while the two hoods on the other side were specific to Kilshon and likely shielded those areas from the back-blast of the missile being fired.

The missile (described later below) fired off a launch rail which was supported by an A-frame and elevated by a hydraulic piston. The launcher assembly also had a reloading work platform on the rear. A travel brace mounted onto the Sherman’s glacis armor unhooked and dropped down for firing operations.

rail

(Detail of the arms, jack piston, and travel brace in the raised position.)

rail3

(The same, but with the travel brace disengaged and lowered.)

rail1

(Rear of the launcher arm with a dummy missile aboard, showing the reloading working platform.)

rail2

(A close-up of the turntable and elevation pivot. The Kilshon vehicle carried two spare roadwheels and a small length of replacement treads, both as a repair aid and a bit of extra crew armor.)

Kilshon: the missile

Immediately after the Yom Kippur War, Israel began work on a successor to the failed Potifar, but using the AGM-45B version of the Shrike. This was called Khalilit, sometimes transliterated as Chachlilit. (As a sidenote, the nomenclature overall is still unclear. Khalilit may have been the project name, or the name for either just the missile or just the Sherman; likewise Kilshon the same to any of the above.)

The project was headquartered at Palmachim, a military base on Israel’s Mediterranean coastline. The first commander was LtCol Avihu Kol, a former army paratrooper who had moved to the air force. Most actual test work was done in Israel’s southern Negev desert.

The Kilshon system was cloaked in great secrecy from the start. It was an air force project, but as it was land-based, it used a great deal of army equipment – most of all the Sherman tank. IAF personnel in the project wore army uniforms. Whenever the team was in public they ensured nothing would reveal that they were air force personnel working on a land-based weapon. The prototype Kilshon was always moved around aboard a lowboy trailer covered in tarps.

The AGM-45B gave the team a few minor improvements right from the start. Besides the longer basic range (25 miles vs 10 miles) the newer Shrike had a “gating” feature where it could pinpoint one specific radar in a group of the same type using the same frequency, eliminating an issue of the missile becoming confused.

Still the basic problem of Potifar presented itself – the Shrike would be starting from 0′ altitude and 0 kts airspeed. For Kilshon, the team developed a solid-fuel rear booster rocket, joined to the tail of the Shrike.

kilshon1

The booster essentially turned the Shrike into a two-stage rocket. It propelled the Kilshon off the rail and to the apogee of the mission’s arc, where it extinguished and dropped off the Shrike. The Shrike’s rocket motor then ignited and flew the weapon to the targeted radar.

Basically the booster performed the role which the warplane would perform in a normal use of the Shrike. The total range of Kilshon was 30 miles, meaning that not only was the AGM-45B’s total range preserved, but an extra 5 miles added.

missile

(The whole Kilshon on the Sherman’s launch rail. This is at a museum display today. The forward portion here is actually a ATM-45 which was an inert US Air Force ground training shape, with fins differing from the actual AGM-45B.)

The Kilshon had to be oriented ±4° at the targeted radar. To avoid the “self-location” problem which might have caused issues with AGM-45A and Potifar, the IAF had teams of surveyors precision-map potential exact firing locations in the Golan Heights. These were then pre-marked for any future war. An actual Kilshon firing platoon also included a military surveyor so they could be used elsewhere.

The AGM-45B Shrike needed a “bob” maneuver to align it in the up/down axis prior to locking on. How exactly the Kilshon addressed this is not known. One possibility is that when the booster separated, it oscillated the Shrike in pitch, completing this task. Another possibility is that the Israelis found some sort of work-around and then just wired that into the Shrike portion of the Kilshon.

While the Sherman lower portion added tremendous off-road mobility in general, it was not intended that the Kilshon vehicle move around a lot with a missile mounted. In transit, the actual missiles were carried by Reo 2½-ton trucks. Unlike Potifar however, the vehicle could move if needed with a missile mounted.

rear

A 50-man Kilshon platoon had three Sherman launchers, one or two missile-bearer Reo 2½-ton trucks, and a crane truck. When action was imminent, the three Shermans parked in a three-pointed star around the crane, which then extracted missiles off the Reos and lifted them onto the Sherman launchers. The Shermans then moved, with missile aboard, short distances away from one another.

Initially the whole system was at the mercy of the crane truck. Later still, a small mechanical arm-type crane was developed so the Reos could themselves put the missiles onto the Sherman launchers.

Attached to the platoon was a weather balloon jeep, to calculate in the aforementioned “atmospheric transition” issue. The platoon also received twice-daily updates from Israeli’s national weather service. Surprisingly all the targeting work was done without computers. It was all pencil-and-paper math or with a cheap civilian calculator.

vehicle

The Kilshon system was fully operational by 1980. A total of 15 WWII Sherman tanks were converted, organized into five firing platoons.

KERES

Keres was the final land-based ARM system, but as it would turn out, the Kilshon would be the final one to use WWII vehicles.

standardarm

As a competitor to the AGM-45B Shrike (which none the less remained in production), General Dynamics developed the AGM-78 Standard-ARM. It was a superior missile, with more than twice the range (56 miles vs 25 miles).

Other improvements were numerous. The biggest was that Standard-ARM had a memory, where if the targeted radar stopped transmitting, the missile remembered its location and hit there anyways. The seeker could be “dialed in” on the ground to whatever radar was being attacked. This meant that squadrons no longer had to keep a variety of submodels in inventory. The warhead was more potent and the missile flew slightly faster.

The problem was price. In the early 1970s, a Shrike cost $7,100 while a Standard-ARM cost $200,000. During the Vietnam War, American squadrons were required to fill out special paperwork each time one was used, explaining to the Pentagon why they felt it had been necessary.

The USA agreed to export one hundred AGM-78 Standard-ARMs to Israel during the late 1970s. Unlike AGM-45 Shrike, which was compatible with any pylon that could fire a AIM-7 Sparrow, the AGM-78 Standard-ARM required a separate contract to Loral Aerospace to rewire the IAF’s F-4 Phantom II fighters.

When Kilshon production ended in the late 1970s, it was decided that the AGM-78 Standard-ARM would make an even better choice as a land-fired anti-radar missile. Besides the improvements above, an advantage was that the AGM-78 was an offshoot of the RIM-66 surface-to-air missile, which started at 0′ altitude / 0 kts. The name of the project was Keres (hook in Hebrew).

It was logically intended to mount the system on a rebuilt Sherman, as doing so for Kilshon had been successful. By now, Sherman hulls were plentiful, as not only had the IDF retired baseline WWII M4 Shermans but also the M-1 and M-50 rebuilds.

However this was not to be. During development, it was commented that however good the Sherman’s off-road mobility was, a Kilshon firing platoon was still tethered to the wheeled Reo 2½-ton trucks that transported the actual missiles. Since this limitation was already accepted, it was then decided to just combine launch rails for the AGM-78 and their shipping containers into a single thing, and have the Reo trucks shoot the missiles themselves.

Keres

This is what was done. The Keres system entered service in the early 1980s. There would be no more pairings of ARMs and WWII armor.

IN COMBAT

Lebanon’s Bekaa Valley is in the western portion of the small country, running north-south inbetween a pair of mountain ranges. A WWII-era highway, still serviceable in the 1980s, cut through the valley east-west between Beirut and Damascus and was the only reliable road link between the two capitals.

_41050259_syria2_lebanon_map203

(map via BBC)

By the 1980s, Lebanon’s civil war was in full swing and this picturesque valley of vineyards and well-preserved Roman ruins had become an extremely lawless place, where it was discovered that the soil and climate were ideal for growing marijuana plants and opium poppies. Besides the narcotics-related violence, the civil war, typically concentrated in the country’s south and seaboard, spilled into the valley. The latter was quelled by the Syrians after they occupied the valley; the drugs were not.

For their own reasons both Syria and Israel intervened in the Lebanese civil war. Syrian soldiers occupied part of the Bekaa Valley, to ensure a road link with Beirut and as a new western air defense flank north of Israel’s Golan Heights. Israel had no intention of occupying the valley, but wanted to control the sky above it to block Syrian warplanes from attacking Israeli forces elsewhere in Lebanon.

sa6gainful1980s

(A dug-in Syrian SA-6 “Gainful” triple-launcher vehicle in the Bekaa Valley during early 1982. This SAM used the “Straight Flush” guidance radar which was not targetable by the Kilshon system.)

Throughout late 1981 and early 1982, the already terrible relations between Israel and Syria further deteriorated due to both having forces in Lebanon. Israel was preparing for a future conflict and a prime consideration was the radar and SAM network already in the Bekaa Valley. In 1981 the IAF had already requested, and been denied, permission to take out Syria’s SA-6 launchers there. Throughout the spring of 1982 training continued, including attacks on mockups of Syrian SAM systems built in the Negev.

Reconnaissance photos showed that Syria was not only failing to reinforce its internal air defenses, but was in fact moving additional radars, SAMs, and AA guns in Syria proper across the Lebanese border into the Bekaa Valley. This indicated that Syria was not gearing up for another direct land invasion of Israel as it had in 1948, 1967, and 1973. Instead, it wanted the impending conflict to be fought inside Lebanon, which was fine with Israel as that freed up additional resources and options.

flatface

(Syrian P-15/P-19 “Flat Face”, the ultra-high frequency target acquisition radar for the SA-3 “Goa” SAM. This radar was vulnerable to either Kilshon or Keres.) (photo via MilInME website)

By early 1982 Syria had nineteen SA-6 “Gainful” batteries in a 25-mile stretch of the valley. There were also SA-3 “Goa” sites in smaller numbers, and on the other side of the Lebanon-Syria border (which by then had ceased to have any real meaning because of Lebanon’s civil war) more batteries of both types plus SA-2 “Guideline” SAMs with reach into the valley.

The last spark which finally ignited the situation was the failed assassination of Israel’s ambassador to Great Britain, done by a Palestinian group operating under Syrian protection in Lebanon.

At 14:00 on 9 June 1982, Israel launched operation “Mole Cricket-19”. The opening act was a wave of sacrificial Mastiff and Firebee drones flown en masse towards Lebanon and Syria. Detected at long range by air search radars, these goaded the Syrians into turning on the targeting and guidance radars of their SAMs. In a pre-timed event, this was followed in short succession (all in about 10 minutes) by the firing of Kilshon and Keres missiles, and a mass SEAD wave of warplanes firing Shrikes and Standard-ARMs from the sky. This was successful, with the majority of the SA-6 radars being disabled.

Israel has always been, was in 1982, and remains today in 2021, very secretive about its SEAD capabilities. Israel has never fully revealed the extent of the role which the ground-fired ARMs played in “Mole Cricket-19”, but needless to say it was not huge. Piecing together anecdotal accounts, there were three Kilshon platoons in the Golan Heights which took part – however, this may be a mistaken transliteration of a single Kilshon three-Sherman launching platoon. There was certainly one Keres truck. All belonged to the IAF’s 153rd Squadron.

No exact breakdown of how Kilshon performed is thus available, at least in the unclassified realm. One fairly believable account said that fewer than a dozen Kilshons were fired, of which all but one missed. Other accounts say that all missed. The failures were not because of the WWII lower portion, but the inherent limitations of the Shrike: either the wrong type of radar was targeted and the missile never locked on to anything, or, the Syrian radarmen realized what was happening (contrary to how western media portrayed them, they were skilled) and momentarily cycled their transmitter off & on with a Kilshon inbound, causing the Shrike to break lock and crash.

In contrast three Standard-ARMs were fired from a Keres truck, and two or all three of them hit Syrian radars.

It is possible (but not likely) that the Sherman-fired Kilshons had a slightly better performance than thought. “Mole Cricket-19” involved a rapid sequence: the drones, then the ARMs against radars, then attacks on the blinded SAM batteries with precision-guided bombs, then a follow-on strike with regular free-fall bombs. In post-strike reconnaissance it wasn’t always possible to determine what had been destroyed by which wave.

In the early / mid-1980s even the existence of Kilshon was a secret. The Israelis realized that civilians (Lebanese, Syrian, or their own) might have seen exhaust trails of weapons ascending off the ground towards the Bekaa Valley. Therefore it was publicly stated that “Mole Cricket-19″s ground-based portion had utilized Ze’ev missiles, a completely unrelated short-range battlefield missile of the Yom Kippur War era. The Ze’ev cover story was maintained into the 1990s.

end of the road

After that one day in 1982, Kilshon was never used again in combat. All were withdrawn in the mid-1980s.

While it was an ambitious and creative idea, this pairing of WWII’s legendary tank and new military technology had, by then, been passed by. The original Shrike entered service 20 years after WWII ended, and at that time it was a game changer. The Kilshon was used 17 years after that, and in the meantime radarmen from Hanoi to Damascus had learned tricks to defeat the Shrike, such as momentarily powering down, or “hop-scotching” between radars of the same type.

Israel continued using the M-51 upgrade of the WWII M4 Sherman into the late 1980s, and repurposed Sherman lower hulls were used in niche roles to the turn of the millennium.

In 1992, Israel finally acknowledged that the Potifar and Kilshon systems had existed. In 1994, a Kilshon-launching Sherman was publicly displayed. Today two of the Sherman-based launchers survive as museum pieces.

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