AIM-7 SAM version?

[saltedfish]

Just got done watching Not a Pound for Air to Ground's video on the AIM-7, and I got to wondering why the AIM-7 was never adapted for surface launching until they started bolting launchers to ships in the 70s.

The video seems to imply that the two major factors that lead to the AIM-7s poor performance were (a) the need to maneuver the aircraft pretty precisely into position in order to properly illuminate the target and then to keep the target illuminated long enough for the seeker to lock on, and possibly more importantly (b) damage to the missiles due to poor maintenance, shock/vibrations from flight/handling and environmental effects.

A ground-based version of the missile would seem to solve many of these issues: the missiles could be stored inside sealed containers until launch, helping to protect them from environmental factors, and a stationary illuminator (with a more powerful power source) might offset the issues with guidance. Certainly once they were put onto ships, they seemed to perform pretty well. But the missile was being launched from aircraft for decades before someone thought to slap it on a ship?

Is there a reason for this delay? It's especially odd when the Navy spent so much time developing the Three Ts when a secret, fourth option was at hand? Or was it that the Air Force didn't want to share their toys?

 

[Dilandu]

Just got done watching Not a Pound for Air to Ground's video on the AIM-7, and I got to wondering why the AIM-7 was never adapted for surface launching until they started bolting launchers to ships in the 70s.

Mostly because it wasn't exactly good for that role. Early version of Sparrow used conical scan seekers, which could be easily confused by echo from surface, trees, terrain, ect. Over the sea it's not a big problem, because reflective capability of sea surface is generally monotonous and could be easily filtered out. But over land, it would seriously limit the low-altitude performance. And without the low-altitude capability, Land Sparrow would not exactly have much more advantages over HAWK.

For 1960s, low altitude interceptions over land were a major headache for the SARH missiles. Too many complex reflections, too hard for missile tiny brain to maintain the target lock. The absolute majority of mobile SAM's in 1960s used command guidance; it allowed to relegate the thinking to much more capable computers (and human operators), while missile merely following orders where to fly.

 

[Dilandu]

Certainly once they were put onto ships, they seemed to perform pretty well.

Actually not exactly. The early Sea Sparrow was considered "better than nothing, but not much better". The launchers were heavy and clumsy (which precluded them from being installed on the small ships - which originally was the whole idea), the illumination radar was manually aimed (and operator only have its Mark 1 Mod 0 eyeballs to track the target, which made the whole system next-to-useless in night or bad visibility) and missile maneuvering capability was insufficient.

But the missile was being launched from aircraft for decades before someone thought to slap it on a ship?

Mostly because Navy started to experiment with Sparrow only after running out of other ideas. Initially, Navy wanted a naval version of Army MIM-46 Mauler - a self-contained unit with automatic guidance and beam-riding & IR guided missiles - as a close-range, low-altitude defense. But Mauler never managed to work as intended, and was cancelled in 1965. They looked on Army's MIM-72 Chaparral as alternative, but it was a tail-chaser only, and Navy wanted a head-on interception capable missile.

 

[yeetmahboi]

They looked on Army's MIM-72 Chaparral as alternative, but it was a tail-chaser only, and Navy wanted a head-on interception capable missile.

And then there's the AIM-9C, already carried by the Cru2s.

Generally I agree with the sentiment that HAWK as a purpose built system is superior to any early iterations of Sparrow by several magnitudes and with how Mauler turned out there was definitely some reluctance in proliferating smaller SAMs like a SL-Sparrow.

 

[Dilandu]

And then there's the AIM-9C, already carried by the Cru2s.

Well, I actually played quite a lot with the idea of equipping the Chaparral with AIM-9C SARH missiles, but my idea was to install a very simple (illumination only) narrow-beam radar that would be slaved to operator optical gunsight (like on Vulcan VADS system, the rangefined radar was slaved to the optical gunsight and could only measure distance to the target, tracked by operator). In combination with IR AIM-9D such concept could work reasonably fine, IMHO.

 

[xena]

Actually not exactly. The early Sea Sparrow was considered "better than nothing, but not much better". The launchers were heavy and clumsy (which precluded them from being installed on the small ships - which originally was the whole idea), the illumination radar was manually aimed (and operator only have its Mark 1 Mod 0 eyeballs to track the target, which made the whole system next-to-useless in night or bad visibility) and missile maneuvering capability was insufficient.

They looked clumsy but they were not heavy. It was a simple system without much electronics under the surface. Something like Seacat in UK. But Sparrow missile was much bigger than Seacat. So it could not fit small ships like Seacat. But for big carrier and many other ships it was ok and a cheap opportunity.

 

[Dilandu]

They looked clumsy but they were not heavy. It was a simple system without much electronics under the surface. Something like Seacat in UK. But Sparrow missile was much bigger than Seacat. So it could not fit small ships like Seacat. But for big carrier and many other ships it was ok and a cheap opportunity.

True, but the original idea was a bolt-on system that could be installed on ships like escorts, minesweepers, FRAM destroyers, landing ships, ect. For that Sea Sparrow was way too big and clumsy.

 

[saltedfish]

I appreciate all the replies!

Regarding ground clutter -- I had it in my head that firing "upwards" would enable the target to be mostly silhouetted against the sky, thus making the SARH more effective than in an aerial dogfight. Apparently this is not the case?

The impression I'm getting from a lot of the reading I've done is that most of the early SAMs and AAMs were all kinda... not great. Which I guess makes sense for the 60s-70s since computing technology was still nascent and engineers were still figuring out high speed aerodynamics.

Mostly because Navy started to experiment with Sparrow only after running out of other ideas. Initially, Navy wanted a naval version of Army MIM-46 Mauler - a self-contained unit with automatic guidance and beam-riding & IR guided missiles - as a close-range, low-altitude defense. But Mauler never managed to work as intended, and was cancelled in 1965. They looked on Army's MIM-72 Chaparral as alternative, but it was a tail-chaser only, and Navy wanted a head-on interception capable missile.

This helps put everything into context, thank you. It makes sense they'd pursue the most promising options first.

On the topic of US SAMs in general, my understanding is the US didn't invest as heavily into SAM technology as, for example, the Russians, because the assumption was the Air Force or Naval Aviation would be providing air cover for ground forces, which made mobile SAM launchers sort of redundant. Is there any truth to this? It does seem like the majority of American SAMs are launched from ships, and the land versions seem to mostly be afterthoughts or shortly-pursued projects.

Are there examples of successful mobile US SAM launchers other than the Chaparral?

 

[Dilandu]

Regarding ground clutter -- I had it in my head that firing "upwards" would enable the target to be mostly silhouetted against the sky, thus making the SARH more effective than in an aerial dogfight. Apparently this is not the case?

It's a bit complicated here. While this method would work against high-altitude targets - i.e. when radar could be aimed at high enough angle for the beam not to touch ground - against low-altitude targets it would work only when the plane is very close to radar.

This helps put everything into context, thank you. It makes sense they'd pursue the most promising options first.

You are welcome)

On the topic of US SAMs in general, my understanding is the US didn't invest as heavily into SAM technology as, for example, the Russians, because the assumption was the Air Force or Naval Aviation would be providing air cover for ground forces, which made mobile SAM launchers sort of redundant. Is there any truth to this? It does seem like the majority of American SAMs are launched from ships, and the land versions seem to mostly be afterthoughts or shortly-pursued projects.

Not exactly. The main problem was, basically, that Army was an underdog, and constantly got under-funded for anything "not essential". The "essential" was assumed to be provided by Nike-Hercules (protection of stationary targets and populated areas), HAWK (protection of bases and deployed troops) and Redeye (close-range protection). While the Army recognized the need of mobile air defense, capable of operating with armor columns, it rarely was considered a priority.

because the assumption was the Air Force or Naval Aviation would be providing air cover for ground forces,

Ironically, this assumption was almost nonexistent in 1960s, because Air Force did not want to provide any air cover. They insisted that their role is to strike enemy rear with nuclear bombs, and that the best way of providing air cover is to destroy enemy air force on airfields, not fighting a dogfights over frontline.

 

[saltedfish]

Not exactly. The main problem was, basically, that Army was an underdog, and constantly got under-funded for anything "not essential". The "essential" was assumed to be provided by Nike-Hercules (protection of stationary targets and populated areas), HAWK (protection of bases and deployed troops) and Redeye (close-range protection). While the Army recognized the need of mobile air defense, capable of operating with armor columns, it rarely was considered a priority.

The interdepartmental rivalry is wild to me. The Air Force's position on the matter seems... really short sighted.

Mostly because Navy started to experiment with Sparrow only after running out of other ideas. Initially, Navy wanted a naval version of Army MIM-46 Mauler - a self-contained unit with automatic guidance and beam-riding & IR guided missiles - as a close-range, low-altitude defense. But Mauler never managed to work as intended, and was cancelled in 1965. They looked on Army's MIM-72 Chaparral as alternative, but it was a tail-chaser only, and Navy wanted a head-on interception capable missile.

What was the issue with the Mauler that led to it being cancelled?

 

[Dilandu]

The interdepartmental rivalry is wild to me. The Air Force's position on the matter seems... really short sighted.

Essentially Air Force wanted to concentrate on nuclear weapon delivery & area protection, and nothing else. Air-to-air combat (outside of interception of enemy long-range bombers, threatening the rear cities) were viewed as superfluous; the dominating idea was, that it's always better to destroy enemy air force on ground, and Army should rely on SAMs instead of diverting Air Force planes from bombing operations. That's why USAF pilots were so inept in air-to-air combat during early Vietnam War. They simply weren't trained enough for that. And that's why USAF lacked any kind of precision air-to-ground weapon to attack such targets as bridges, too. The assumption was, that such targets should be attacked by nuclear weapons.

What was the issue with the Mauler that led to it being cancelled?

To put it simply? It didn't work.



The whole system was overcomplicated from the beginning. The system was supposed to use a multi-channel aquisition radar for target search and separate tracking/illumination radar for missile guidance. The missiles were initially supposed to have beam-riding guidance, but it was found to be not accurate enough, so they switched to semi-active radar seekers (and later, out of desperation, tried to adapt the Redeye seeker). And all this was supposed to be set on one M113 chassis.

The development was prolonged and complicated, with many revisions and delays and requirements changes. And when they finally tried to test the system circa in 1963... it just didn't work. The tracking radar was unable to discriminate between the missile & fast target - it could just lose the target and start to track the missile itself. The missile's guidance systems were half-deafened by their own electronic components noise. The missiles themselves have major aerodynamic problems, that caused them to spin out of control. The launch containers, huddled together in 3x3 formation were placed too close, and launch of one missile damaged the others. Many of fire control system electronic components were re-designed by different teams so many times, that they basically became incompatible.

The program was eventually turned from weapon development into research & development, and - despite some progress, including replacing semi-active guidance with infrared one - was eventually deemed unsalvageable and cancelled in late 1960s.

 

[BlackBat242]

True, but the original idea was a bolt-on system that could be installed on ships like escorts, minesweepers, FRAM destroyers, landing ships, ect. For that Sea Sparrow was way too big and clumsy.

Well, they did make it aboard the Knox class... on the stern:

 

[Dilandu]

Well, they did make it aboard the Knox class... on the stern:

True, but Knox-class weren't exactly "small units".

 

[Scott Kenny]

Are there examples of successful mobile US SAM launchers other than the Chaparral?

The missile system now known as Crotale NG. It was a competitor in the ADATS competition where it was called Liberty VT-1, and did well enough to be adopted by France. Has radar tracking, thermal tracking, and visual tracking, with radar and IR search systems.

 

[xena]

True, but Knox-class weren't exactly "small units".

From a modern point of view they were small. BPDMS could also be installed on FRAM ships, but then instead of the Asroc, not because of the weight, but because of the size. Or instead of the drone on their landing platform. That was not the purpose of these ships. All guided missiles were larger than ww2 weapons, so the ships were also larger. BPDMS was ideal as light weapon on aircraft carriers as additional weapon on cruiser and destroyer. An it did well, because it was smaller and lighter than Tartar.

 

[xena]

The missile system now known as Crotale NG. It was a competitor in the ADATS competition where it was called Liberty VT-1, and did well enough to be adopted by France. Has radar tracking, thermal tracking, and visual tracking, with radar and IR search systems.

So far I know the missile came from US but the Crotale II system was French.

 

[Archibald]

The missile system now known as Crotale NG. It was a competitor in the ADATS competition where it was called Liberty VT-1, and did well enough to be adopted by France. Has radar tracking, thermal tracking, and visual tracking, with radar and IR search systems.

It became the Clemenceau and Foch close air defense system after early 1980's mid-life SLEP, replacing old guns. Just like CdG has Aster 15 nowadays.

 

[Dilandu]

From a modern point of view they were small. BPDMS could also be installed on FRAM ships, but then instead of the Asroc, not because of the weight, but because of the size. Or instead of the drone on their landing platform. That was not the purpose of these ships. All guided missiles were larger than ww2 weapons, so the ships were also larger. BPDMS was ideal as light weapon on aircraft carriers as additional weapon on cruiser and destroyer. An it did well, because it was smaller and lighter than Tartar.

Theoretically it could be installed in place of upper turret (which was already removed on FRAM II ships), but the space would be rather tight.