Continental Air Defense

As the Cold War started heating up in the late 1940s and early 1950s, particularly after the USSR detonated its first atom bomb in 1949, the great fear was that fleets of Soviet bombers would attack the US.  The opacity of the USSR meant we had no real idea of the size of the Soviet bomber fleet. At a minimum, we knew they were equipped with a cline of the B-29, known as the Tupolev Tu-4 “Bull.” As we advanced our own bomber designs, it was sensible to presume the Soviets were likewise building more advanced designs.

The challenge of defending the airspace of the US lead to two massive defense programs, one Air Force and the other Army.

The Air Force spent billions forming and equipping the Air Defense Command, and later integrating it with the Royal Canadian Air Force as the North American Air Defense Command. Why Canada? The shortest, most logical route for any Soviet bomber attack against the US would be by flying over the arctic and through Canada’s airspace.

ADC, and later NORAD had a network of radar stations to detect any incoming attack, air defense sector control stations to direct interceptions, and widespread fighter interceptor bases from which to attack the Soviet bombers. Plus, of course, hundreds of interceptors to actually do the attacking.

But US experience in World War II had clearly shown that no matter how determined any fighter attacks were, at least some bombers would penetrate to the target area. Clearly, some form of terminal defense was needed.

The Army first started by emplacing large numbers of anti-aircraft guns in rings around major US cities. But WWII had also clearly shown that even the best anti-aircraft guns had low probabilities of killing a target. In the age where only one bomber had to reach a target, something better was needed. The advent of jet propulsion would also mean bombers would soon be flying far above the range of any conceivable gun.

The Army had actually began to explore the possibility of using guided missiles for air defense as early as 1944. The V-1 buzz bomb attacks were bad enough. But the frustration at having no defense against the V-2 ballistic missiles lead the Army to consider the possibility of using missiles as a defense. Alas, it was beyond the state of the art at that time, but the germ of an idea was planted. The need for improved terminal defense in the US lead the Army to launch Project Nike.

After a development program at speeds that would stun any procurement official today, the first fruits of Project Nike lead to the Nike Ajax missile, which made its first intercept in 1951. By 1953, the missile was ready for deployment.

Nike Ajax

Nike Ajax Missile

The Nike Ajax was a two-stage guided missile fired from a rail launcher. The missile itself was 21 feet long, and the booster stage was 13 feet long. The booster was a solid fuel rocket, while the sustainer motor of the missile was liquid fueled, with kerosene as the fuel, and red-fuming nitric acid as the oxidizer.

Four launchers, and a Battery Control Section consisting of an Integrated Fire Control (IFC) van, and the three associated radars formed a battery.

The missile was guided by a command guidance system that consisted of three separate radars. First, a long rang target acquisition radar (cued by one of the Sector ADC commands) would detect the target. The acquisition radar would then hand off the contact the the Target Tracking Radar. When the target was in range, the battery commander would launch the missile. By way of a transponder in its tail, the Missile Tracking Radar tracked the Ajax missile. By comparing the positions of both the target and the missile, the IFC could develop an intercept solution, and then send steering commands to the missile by injecting them into the MTR signal. The missile would be detonated by command from the IFC.  The Nike Ajax had an unusual, and large, three part warhead, spread along the length of the missile body to help ensure target destruction. The Nike Ajax had a range of about 25 miles, which wasn’t bad for a first generation guided missile.

The Army originally intended the Nike Ajax system to be semi-mobile, but since the targets it would defend weren’t going to move, they redesigned the system to operate from fixed locations. Since major metropolitan areas are spread out, that meant that cities such as New York, Los Angeles and Chicago would need several batteries to form a ring around them. Between 1953 and 1962, the Army built 300 Nike batteries scattered across the country, most near major metropolitan areas or Strategic Air Command bomber bases.

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Nike Ajax Batteries in the US- Click to embiggen.

Each battery had three sites- The Control Site, the Launcher Site, and the Administration Site.

The Control Site housed the Integrated Fire Control van, and also housed the three radars of the battery. It was usually located on the highest ground available in the sector that was being covered. The Launcher Site was usually located within a mile or two of the Control Site. Originally, the Launcher Sites had been intended to store their missiles above ground, but the pressure to reduce the real estate footprint of the batteries lead to the Army building underground magazines to store the missiles. Each Launcher Site had four launchers, and an underground magazine holding twelve missiles. Missile assembly, checkout, maintenance and preparation would take place in the magazine, then a powered elevator would lift the missile above ground. It would then be transferred to the launcher rail, and ready to fire.  The Admin Site was home to the offices, motor pool, barracks and messing facilities for the battery. It was usually, but not always, co-located with the Control Site.

Each battery had just over 100 soldiers assigned. Batteries were assigned to a Defense Area responsible for the target area defended. These Defense Areas controlled anywhere from two to twenty-tw0 batteries. All these Defense Areas reported to the Army Air Defense Command or ARADCOM.

Nike Ajax was a remarkable achievement, and would have been fairly effective against Soviet Tu-4 and Tu-95 Bear bombers. But the missile had a short range, and if the Soviets started developing higher flying, supersonic bombers like the US was developing, something better would be needed. In response, Nike Hercules was developed.

Nike Hercules was intended from the start to be used from the same bases as Nike Ajax, with minimum modifications. The main improvement was not to the guidance systems, but to the missile itself. Hercules was a much larger, faster, and higher flying missile. It too was a two stage missile. It’s booster was essentially four Ajax boosters strapped together. Improvements in solid fuels meant the finicky liquid propellants could be disposed with and the sustainer motor of the Hercules was solid fueled. A maximum speed of almost Mach 4 gave the Hercules a range credited from about 85 miles to up to 100 miles. It could engage any existing or projected bomber, and it could even target short and medium range ballistic missiles.

Nike Hercules

Nike Hercules

The Hercules much longer range also meant fewer batteries were needed to cover a given target area. This meant the Army could relinquish expensive land in metro areas, and reduce the total number of soldiers dedicated to the air defense mission.

Most Nike Hercules used in the US were armed with a 20 kiloton nuclear warhead. Now, the idea of popping off a nuke twice the power of the one dropped on Hiroshima over Manhattan might not have been terribly appealing, but Army planners figured it beat the alternative of a 5 megaton nuke detonating right on Wall Street.

The Nike Hercules was also widely deployed overseas, particularly where the US had bomber and missile bases, such as in Germany, Greece, Turkey, Okinawa and Korea. Missiles overseas were armed either with the nuclear warhead or an 1100 pound conventional warhead.

The Nike Hercules system remained operational in the US continental air defense role until 1974 though a handful of sites were still employed along the eastern seaboard. By that time, the primary threat to the continental US was Soviet intercontinental ballistic missile systems. Further, the SALT I agreements categorized the Hercules as an anti-ballistic missile system.  Budget pressures in the post-Vietnam era also reduced the ability to provide what was increasingly a very limited capability.

Even as the Nike Hercules was being designed, the Army recognized that intercontinental ballistic missiles (ICBMs) would become the primary threat to the US. Development began in 1959 on a missile system to counter that threat, the Nike Zeus.  Unlike the Hercules, the Nike Zeus used entirely new radars as well as a radically different missile.

Nike Zeus

Nike Zeus

As early as 1962, Zeus actually intercepted an ICBM target at Kwajalein Island in the Pacific. In spite of this impressive achievement, the program was plagued with technical difficulties and cost overruns. Development was scrapped in 1963, but technologies from the program were used in the development of the Sprint/Spartan Anti-Ballistic Missile program that was (very briefly) deployed in 1975.

As the Army got out of the continental air defense business, hundreds of sites were decommissioned and either turned over to the National Guard (in fact, many batteries had been operated by the Guard), other federal agencies, or to the states or cities.  San Francisco is home to the only preserved launch site, SF-88L, which is open for tours. The remains of other launch sites can be discovered with a little detective work.

Addendum: Since shooting live missiles over cities was generally frowned upon, and the launching equipment was of a fixed site design, crews would travel to White Sands Missile Range in New Mexico for live fire training. All Ajax missiles used a conventional warhead, and Hercules crews would live fire the conventional warhead version of the missile.

Addendum 2: For you sharp eyed observers out there, you probably noticed a similarity between the Nike Ajax and the Soviet SA-2 Guideline missile system. They were in fact contemporary systems, and used similar configurations and guidance techniques. The similarity between them isn’t so much an example of espionage leading to reverse engineering, but of the state of the art leading separate groups of engineers to propose similar concepts to solve a given problem. But where the Ajax system was withdrawn from service fairly quickly, and replaced by the Hercules, the Guideline can still be found in service in modified form in some former Soviet client states. Modest improvements in the missile itself and more radical changes to the radars supporting the system kept the Guideline viable as a mid-range, mid- to high-altitude anti-aircraft system.

MANPADS

You’ve probably seen the news reports of missiles missing in Libya. And you’re almost certainly familiar with the story of US Stinger shoulder fired missiles being supplied to the mujihadeen in Afghanistan during the Soviet War there. What you may not realize is just how long shoulder fired anti-aircraft missiles have been around.

Less than 10 years after the Sidewinder missile entered service, someone had a bright idea. The Sidewinder was originally based on the 5” unguided rocket. What could be done with the smaller 2.75” rocket? As it turned out, quite a bit. Not that it was easy and quick, but a small rocket, a simple guidance system would eventually lead to the worlds first Man Portable Air Defense System or MANPADS, the FIM-43 Redeye.

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If you compare the Redeye to larger air defense systems, it’s not that impressive. But when you consider that it was the replacement for the quad .50cal mount, it comes off a bit better.  A quad .50 needed a pretty substantial truck to move around, as well as a crew of three or four. The Redeye, on the other hand, only had a two man crew (one man, in a pinch), and could easily move around the battlefield on a jeep or by hitching a ride on the vehicles of supported units. Heck, a paratrooper could jump with the thing.

It also had a better range than the quad .50 and a higher probability of kill or Pk.  It lacked the quad .50s utility for engaging ground targets, but given the massive size of the Soviet Frontal Aviation units facing the Army in Western Europe, that was a decidedly secondary consideration as far as Air Defense Artillery was concerned.

The missile itself was issued as a round of ammunition, stored and fired from a sealed tube. A reusable pistol grip firing device was attached to the tube, and the weapon was ready to fire.

Since the motor exhaust of a 70mm rocket would likely fry the face of the gunner, a small “starter” motor fired very, very briefly to kick the round out of the tube, with the main sustainer motor igniting when the missile was a few meters downrange.

The missile was not without its limitations. Its infrared seeker system was a lead sulfide system similar to early Sidewinder missiles, and like early Sidewinders, could only track the target airplane’s hot exhaust. This meant that Redeye gunners could only engage planes that were moving away from the gunner, most likely after having attacked our friendly unit. Without getting into the whole science of relative motion and kinematics, it also meant the practical engagement range suffered from geometric limitations.  It was also vulnerable to spoofing by high intensity flares and later “brick” infrared jammers.

Even with its limitations, it was an amazing feat to build such a missile as early as 1961, and eventually introduce it into widespread service by the late 1960s. Virtually every successful man portable system since then has closely followed the concept of the Redeye.  Indeed, very soon after the introduction of the Redeye into Army service, the Soviet SA-7 GRAIL near-clone entered service. The SA-7 was soon supplied to the North Vietnamese, and was a dire threat to US helicopters in Vietnam.

The US almost immediately started development of in improved model which eventually became the Stinger missile (we’ll write about that some other time). The Soviets built upon the success of their SA-7 with a variety of different systems, up to about the SA-24 system right now. IIRC, the series includes the SA-14, SA-16, SA-18 and SA-24.

We’re all familiar with the US supplying Stingers to the Mujihadeen. But the fact of the matter is, the majority of US supplied missiles were actually Redeye missiles (though a large number of Soviet made SA-7s were also supplied by the CIA).  We’ve all seen the terrific pounding our helicopters have put on Iraqi and Afghani insurgents. The Mujihadeen faced similar punishment from Soviet attack helicopters… right up until we supplied them with an air defense weapon that struck fear into the hearts of Soviet aviators.

[youtube=http://www.youtube.com/watch?v=GtVShpxDeOs&w=448&h=252&hd=1]

[youtube=http://www.youtube.com/watch?v=e-s4u4l5BPo&w=448&h=252&hd=1]

Talos

USS Long Beach (CGN-9)
Image via Wikipedia

Continuing in our series on US missile systems.

The US Navy’s experience against the Luftwaffe in the Mediterranean Sea during World War II became the impetus for development of long range guided missile systems. The HS293 and Fritz X guided bombs gave Luftwaffe bombers great enough standoff range to avoid most anti-aircraft fire, and sufficient accuracy to be deadly to ships. The need for a weapon with much greater range than the standard 5’/38 gun was clear. The added devastation inflicted by the Kamikazes (especially the Baka bomb) in the last stages of the Pacific War only added urgency to the desire to develop a long range weapon system.

Simply adding bigger guns was not a terribly practical approach. Larger guns would theoretically provide longer range, but the increasing speed of aircraft, especially jets, and the longer range would decrease gun accuracy unacceptably. Coupled with the greater weight and lower rate of fire of a larger gun system, little benefit would be gained. The Navy had been unimpressed with Japanese cruisers using 6” and 8” guns as “dual-purpose” guns (that is, against surface and air threats). Nevertheless, at the very end of the war, a dual purpose 6” gun mount was designed for our Navy. It was not terribly successful, and other approaches to long range anti-aircraft fire were pursued instead.

The “outer layer” of a fleet’s air defense was provided by its fighters, operating radar control from the carrier, picket destroyers, and finally, via Project Cadillac, airborne radar planes.  But the Combat Air Patrol sometimes let “leakers” through, and the carrier’s cruiser escorts needed a way to solve that problem.

Enter Project Bumblebee.1 The navy decided to build a guided missile system. Early solid rocket motors were not powerful enough to provide the range and altitude needed, so the development settled on ramjet propulsion. Ramjets are very simple engines, with essentially no moving parts. But they have to be boosted to high speed before they can work. So an enormous solid booster was needed also just to get the missile off the ship and up to speed.

This ramjet powered missile, later christened Talos, used beam-riding guidance. The launching warship aimed a pencil beam of radar energy at the target aircraft and the missile centered itself on the radar beam and eventually intercepted the target. Since the radar beam was pointed at the target aircraft, there was radar energy reflected back toward the ship- and the missile. As a final guidance mode, the Talos used 4 nose mounted antennae to steer the missile toward the radar reflection, a mode known as Semi-Active Radar Homing or SARH.2

Coupled with the large warhead needed and the bulky electronics of the late 1940s, this resulted in a missile almost as big and heavy as some fighters of the day. The tracking and illumination radars were large and heavy as well. Clearly, this wasn’t a system adaptable to smaller warships such as destroyers. The logical choice was to modify some of the many cruisers left over from World War II, many of which had barely entered service when the war ended. By removing the after main gun turret, revamping the magazine spaces, and rebuilding the topsides (to accommodate the guidance and illumination radars) it was possible to install a Talos missile system onto three Cleveland class light cruisers. Even more radical modifications to Baltimore class heavy cruisers resulted in the three ships of the Albany class with Talos systems for and aft. The only other ship to operate the Talos system was the only nuclear powered cruiser ever built, the USS Long Beach. The Talos system worked, but was far to expensive to be installed on large numbers of ships.

As development of the Talos progressed, the range of the missile increased greatly from its initial goal of 10 nautical miles. By the time the first operational missiles were deployed, the system had a range of 50 miles. Later improvements almost doubled this range. Coupled with the ability to carry a nuclear warhead (to defeat mass attacks), the RIM-8 Talos system was a potent long range system. Three MiG pilots in Vietnam learned the hard way not to stray too close to any Navy task force equipped with it.

After only 20 years of service, the Talos was retired from active duty. Other smaller, lighter, cheaper missile systems were providing similar performance (though usually at somewhat shorter ranges) and could be installed on smaller, more numerous ships. The remaining Talos missiles were used as targets representing supersonic cruise missiles. Descendants of the Talos proved their capabilities by shooting down their predecessor.

[youtube=http://www.youtube.com/watch?v=IaeDP4p1qZI&w=448&h=252&hd=1]

One of themissile systems that replaced the Talos was Terrier. Terrier actually began life as a two staged, rocket powered test vehicle to validate the guidance system of Talos. As solid rocket motors improved, it quickly became clear that Terrier itself would be a viable weapon system, and it actually entered into service before Talos. Tartar, a smaller missile, basically a Terrier without the first stage booster, was developed from Terrier and equipped smaller destroyers and frigates. Since all three missiles sprung from the same intellectual well of Project Bumblebee, they are usually referred to as the “3T” missiles. For 20 years, the 3T’s formed the backbone of the Navy’s surface air-defense system, until replaced by the Standard Missile System.

1 Sometimes called “Operation Bumblebee”

2 SARH was for many years the most common radar guidance method, and is still used to this day by many missile systems, including the Aegis/Standard missile system on US Navy cruisers and destroyers.

Skipper

I hadn’t really intended to start a series on various missiles, but I enjoy watching the youtube videos, so I might as well share with you.

Back in the early 1980s, the Navy faced the challenge of small missile armed fast attack craft in close waters such as the Mediterranean Sea or the Persian Gulf. Widely used, ships such as the Osa II or La Combatantte III were capable of dashing out from port, firing a salvo of anti-ship missiles, and scurrying back to port. While the Navy had the R/U/AGM-84 family of Harpoon missiles to attack surface targets, the Navy also wanted more than one weapon available. Further, the Harpoon had a relatively small warhead, and something a little bit heavier was wanted. But even during the Reagan buildup, money for new weapons was tight.

Someone at the Naval Weapons Center China Lake  (the same bright folks that brought us the AIM-9 Sidewinder) had the nifty idea of using a laser guided bomb as the basis for a new missile. By strapping two surplus rocket motors from the obsolete AGM-45 Shrike missile to the back of a 1000 pound GBU-16 LGB, they could achieve a standoff range of about 15 kilometers, more than enough to keep the launching aircraft out of anti-aircraft missile range of most small attack aircraft. And its heavy warhead was almost certain to knock any small warship out of the fight. The resulting AGM-123 Skipper II served for several years, and saw some combat action. It was a simple, quick, cheap solution to a nagging problem, and the development costs were very low. No wonder the Air Force never adopted it.

[youtube=http://www.youtube.com/watch?v=dBqlBAj0Vw0&w=448&h=252&hd=1]

There never was a Skipper I, by the way. The “II” refers to the fact that the Skipper was built using the Paveway II guidance package.

B

RAM

The Rolling Airframe Missile is a point defense weapon developed jointly by the US and Germany to provide close-in defense to surface ships against anti-ship cruise missiles.

By taking the body of a Sidewinder missile, and combining it with the seeker system of the Stinger missile, development costs were kept to a minimum. The launcher is cued to the target by the ships radar, but the missile is a fire-and-forget system. A passive radio frequency seeker detects the anti-ship missile’s seeker radar or radar altimeter, and directs the RAM to the general vicinity of the target. As the RAM approaches, its passive infrared seeker head locks on and guides the missile to impact.  The RAM has a couple advantages over the older Phalanx Mk15 CIWS. It has a significantly longer range than the CIWS, and it has a 21 round launcher, giving it more engagements before reloading than the CIWS. There is also an 11-round launcher based on the radar and mount of the Phalanx in development.

The latest versions of the RAM can engage helicopters, aircraft, and surface targets. The last bit, surface targets, is becoming increasingly important, as the Navy is very concerned about ships being swarmed by small boats.

[youtube=http://www.youtube.com/watch?v=Xvo7Mb9EwJY&NR=1&feature=fvwp]

I got nuttin’

I can’t find anything interesting today, so here’s some videos of TOW missiles.

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