Sea Indigo

[Howedar]

Adorable! I'd seen the missile, but never the launcher. Any idea as to the scale of the director set?

For scale, Sea Indigo is 3.076m long.

 

[RP1]

The Naval Institute Guide to World Naval Weapons Systems seems to indicate that Super Fledermaus is 1m in diameter.

RP1

 

[Petrus]

Adorable! I'd seen the missile, but never the launcher. Any idea as to the scale of the director set?

For scale, Sea Indigo is 3.076m long.

Sea Killer Mark 2's length was 4.7 m.

Piotr

 

[Petrus]

This is an article on the Indigo missile system from the "Flight International" magazine of 25 January 1973:

Indigo is a low-level and very-lowlevel anti-aircraft missile which became operational last year with the Italian Services. It is fired from towed or self-propelled launchers and is designed for use with a wide range of existing fire-control systems such as Contraves' Superfledermaus (in the towed version), or Thomson-CSF Mirador Eldorado acquisition and tracking radars coupled with Officine Galileo's fire-control unit (when the self-propelled launcher is used). The six-round missile launcher can be deployed on a gradient of up to 7° and can be trained and elevated extremely rapidly. Indigo may be fired singly or in salvo (two missiles), the method of operation being selected by the engagement computer, but with a manual override being possible. A typical firing sequence when beamriding guidance is being used is:

T = 0sec—The alarm is given by the acquisition radar, the target is identified and information is passed to the tracking radar.
T = 3sec—The tracking radar locks on to the target.
T = 6sec—The fire director, acting on information displayed by the engagement computer, starts the automatic firing sequence.
T = 8sec—The motor of the first missile ignites and the ballistic flight phase begins.
T = 10sec—The guided phase of flight begins.
T=.10-5sec—The motor of the first missile burns out and that of the second missile is fired if a salvo launch has been selected.

The weapon can also be used with optical fire-control. In this case the target is identified, the range is established and the missile is armed. Launch then comes under the control of the fire-control officer and guidance is by radio command, using an infrared sensor to determine the missile's deviation from the optical axis.

Indigo leaves the launcher under the impulse of its single 3,750kg-thrust solid-propellant booster, supplied by Imperial Metal Industries, at an initial speed of 850m/sec and can be accelerated at 30g for manoeuvring. After 10km of flight these values are 240m/sec and 8g. The weapon- is effective against aircraft flying at up to Mach 1-3 between altitudes of 15m (nominal) and 5,000m, and has a slant range of 10km. Control is by cruciform wings on the fuselage centre section, with stabilising tail fins. Radio commands are sent to correct dynamic errors resulting from the curvature of the missile's trajectory during beamriding guidance.

Detonation of the 22kg axi-symmetrical fragmentation warhead is by impact or infra-red proximity fuzes.

A naval version of Indigo is under study for ship point defence, using Contraves' Sea Hunter fire-control system.

As for the naval variant, I wonder how many missiles the revolving magazine could have had. Watching its drawing I think there were to be two missile "drums", one beneath each of the launcher's arms (in the picture only one is visible). Any opinion (or - even better - information) would be really welcome.

Piotr

 

[RP1]

The drum appears to be designed to load both arms at once - if you look closely it is more of a polygon than a circle in cross section, which each "bay" formed by the flanges holding 2 Small or 1 large missiles.

RP1

 

[Petrus]

I have just found notes that I took while reading Jane's publications a few years ago. Among them there is a note on the Sea Indigo system: there were to be two versions of it. One intended for larger ships, which has already been described in previous posts here, and the other for smaller ships displacing around 500 ts. It would have had a quadruple launcher that was to be reloaded manually.

Unfortunately, I have never found any pictures of the launcher. Perhaps though someone else did?

Best regards,
Piotr

 

[Howedar]

I've never heard of such a creature. I wonder if it would have ended up more influenced by UK launchers (like the quad-armed lightweight Sea Wolf launcher) with individual boxes around a center trunnion, or more of an American-style box cluster between a pair of trunnions.

 

[Petrus]

I have no idea. But at the moment I am looking at a photo of a Libyan frigate "Dat Assawari" that was built by Vosper, which had an Italian designed and made launcher for the Aspide missiles. It had for containers side-by-side mounted on a pillar. I suspect the Sea Indigo launcher could have been similar, if the Italian engineers had followed the same "style" in case of this system too.

Piotr

 

[Petrus]

I'm sorry, I have forgotten to attach the photo I mentioned. Here is the four-cell Albatros launcher for the Aspide missiles on-board of the Libyan frigate.

Piotr

 

[batigol]

Could this possibly be the launcher? I found this picture on an Italian forum and for the life of me I haven't been able to find the site again.

 

[Petrus]

Could this possibly be the launcher? I found this picture on an Italian forum and for the life of me I haven't been able to find the site again.

Surely it is the Sea Indigo launcher.

Piotr

 

[Pioneer]

Wow that seems quite a large launcher for such a small vessel!

Regards
Pioneer

 

[Nico]

I'm really delighted to see that interest in an old Italian missile system.
Unfortunately I lost a photographs of the mock-up of a very early experimental Contraves Italiana Indigo-G surface-to-air missile, but I found some other interesting shots. The first shows the Indigo-I version (I think the cylinder in foreplane is a section of the rocket engine).
I found also a diagram of the complete Sistel Indigo/Fledermaus weapon system. This version had a wheeled six-cell launcher and was offered to the Italian Army.
I have also a photo of a test firing from that launcher (SISTEL Indigo launch_2.jpg).
Later-on was developed the Indigo MEI you mentioned in your post, a self-propelled weapons system with Thompson-CSF fire control radar mounted atop an OTO-Melara (FMC) M548 MEI armored carrier. I enclose also another shot of a test firing during Sisties or Seventies.
Unfortunately I lack any pictures of the naval Sea Indigo version.

Nico

 

[Thiel]

Maybe a bit off topic, but does anyone have some more info on that corvette?

 

[Grey Havoc]

From FLIGHT International, June 7th 1973:

Sistel Indigo The Italian Army now has an evaluation
battery consisting of a six-round launcher and six reload
missiles. The definitive system is self-propelled and consists
of three vehicles—a launcher, using the present equipment
mounted on an M548 tracked vehicle; a radar vehicle,
again using an M548 (Elettronica San Giorgio is about
to deliver an evaluation model of the radar); and a crane
for loading the missiles. Sistel is not hopeful of a large
order from the Italian Army and is concentrating on export
sales. Sea Indigo has virtually been abandoned.