Almost as soon as the Navy managed to get the 3-T missile family into service (that is, the Talos, Terrier, and Tartar missiles and their associated launchers, guidance radars, and missile control systems), they began to look for ways to improve the actual missiles themselves. The pace of improvements in electronics and solid rocket motors was such that far more effective and reliable missiles could be built than those already in service. But whatever missiles were built would have to be backwards compatible with existing launchers, handling systems, and missile guidance radars and control systems. The desire to achieve commonality was also present. But the variety of different first generation systems in use meant that while some core components could be common, there would have to be some level of specialization. In the end, the Navy bought a family of similar missiles that shared a basic architecture, and came to be knows as the Standard Missile (no cool nicknames here!).
A bit on missile designations here. US missiles tend to have more than one name or designation, and they can be quite confusing. The actual missile itself is usually knows by a tri-service designation with a three letter prefix showing its launch platform and purpose, as well as its numerical designation in that sequence, and a suffix letter showing which variant of the basic missile it is. That same missile tends to have a common name as well (in this case Standard is a “proper name”), but even that name may be modified. Even further confusing, the entire system of handling equipment, launchers, radars and control systems may be referred to by a name (and its own designation under a separate tri-service series of designations) that doesn’t quite seem to add up. Finally, the Standard missile family has evolved in “series” and variants are routinely referred to by those series, i.e. SM-1, SM-2, SM-3, SM-6, and further, especially the SM-2 series has evolved in “Blocks” such as SM-2 Block III.
I’ll try to keep the alphanumeric jargon to a minimum.
When the move to the Standard missile program began, the long range Talos missile was only in use on a handful of ships, and was considered satisfactory for the time being. Accordingly, the Standard program focused on replacing the medium range Terrier missile, and the short range Tartar missile.
Using an airframe almost identical to the Tartar missile, the first series of Standard missiles came in two varieties, the MR and the ER. The RIM-66(SM-1MR) was a single stage missile for use on lighter, destroyer sized installations and was a medium range missile. It was used with the Tartar Missile System, and little modification was needed to those Tartar equipped ships. The RIM-67 (SM-1ER) was a virtually identical missile, but was equipped with a solid rocket booster. It was used on ships equipped with the Terrier missile system. Again, few modifications were needed to adapt the ship to the new missile.
Both these missiles in the SM-1 family were semi-active radar guided. That is, the launching ship had radars, looking much like searchlights, that would shine a radar beam on the target. The missile would sense the reflection of this beam off the target, and steer toward it. The missile had to be guided from launch to impact. And ships were limited in the number of these “illuminators” they could carry. Generally, they only had as many illuminators as launch rails, usually two. Given the limited numbers of missiles they could control, and the limited time for engagement available, a ship could quickly find itself overwhelmed by a “saturation” attack. The Soviets planned to fire dozens, even hundreds of missiles at shipping targets. If they all arrived at roughly the same time, the defending Navy missile ships would kill some, but in the meantime, many others would strike their targets.
Extending the range of the missile helped some. But it also meant that a longer missile flight tied up illuminator time as well. The ability to cope with saturation attacks was a goal of the Navy for many years. First the Typon program tried to address it, but it collapsed under its own weight due to technical challenges and exploding costs. The second attempt was the Aegis program. Aegis began as a missile guidance program, but evolved into an entire battlespace management system. The increase in computer power over the 1970s allowed Aegis to succeed where Typhon had failed. But still, even an Aegis cruiser only carries four illuminators. How do you cope with more than four targets at once? The answer is to time-share the illuminators. Aegis was coupled with the SM-2 family of missiles in a way that didn’t require the target to be illuminated throughout the time of flight.
With the SM-2 family, the missile would be launched and pointed in the general vicinity of where the interception was expected to take place. The radar system would update the location of the target, the location of the missile, then inject steering commands into the radar signal to steer the missile to the updated intercept point. Only during the last few seconds of the interception would the target need to be illuminated. Thus, four illuminators could handle a vastly greater number of interceptions at one time. As an added benefit, the missile itself was flown along a much more kinematically efficient path, and thus had much greater range, meaning even more time was available for more interceptions. Older non-Aegis equipped ships armed with the ER missiles were updated under a program known as New Threat Upgrade (NTU) to have a similar capability.
After the first five Aegis cruisers entered service, the Navy switched to the Vertical Launch System to carry guided missiles. Since the missile didn’t have to be guided to the target the entire flight, it didn’t have to be pointed at the target before launch. Instead, the autopilot would steer the missile in the general direction, and the update/terminal guidance process would begin. This had quite a few advantages. First, eliminating mechanical launchers meant a lot less maintenance was needed. Second, for a given volume, a greater number of missiles could be carried. Finally, each “cell” of the VLS could be loaded with any of a variety of missiles, either one of several Standard variants, the Vertical Launch ASROC rocket boosted torpedo, or of course, the Tomahawk land attack missile. While the cells of the VLS were too small to accept the RIM-67 with its booster, a large diameter, but shorter booster could be fitted, leading to the RIM-156 SM-2ER Blk IV family with an effective range of up to about 130 miles. Not bad, when you consider the original SM-1MR had range of about 15 miles.
The SM-3 leverages improvements in booster and sustainer motors linked with an all new reaction thrust controlled kinetic kill vehicle to provide an effective anti-missile system against medium and intermediate range ballistic missiles. Planned improvements should give the SM-3 family a viable ability to intercept intercontinental ballistic missiles. This is the missile that will equip the cruisers and destroyers providing a missile shield to Europe under the Obama administration’s deployment plan.
The SM-4 was intended to be a family of land attack missiles using remanufactured earlier missiles with GPS and inertial guidance, but was cancelled.
SM-5 seems to have not been used.
The SM-6 family incorporates the improvements of the later SM-2 missiles with a modified guidance radar from the AIM-120 missile to provide self contained terminal guidance, reducing further the demand for “guide time” from the launching ship’s illuminator radars. It also incorporates an infrared homing system adapted from the Sidewinder missile program.
We mentioned in an earlier post the Standard ARM, using the earlier SM-1 airframe to provide a long range anti-radar missile during the Vietnam War. There was also an “interim” surface launched version of the STARM used on some surface ships, giving a limited anti-ship capability until the Harpoon guided missile was fielded.
The Standard missile family will likely continue to evolve, and there are no plans to replace it in US Navy service in the foreseeable future. Not bad for a weapon system over 45 years old.