2009/03/23

Streetfighter, LCS and the small warship problem

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"Streetfighter

As of mid-2001 the Office of Naval Research was considering construction of a Littoral Combat Ship with a displacement of 500 to 600 tons. The LCS would have a draft of about three meters, an operational range of 4,000 nautical miles, and a maximum speed of 50-60 knots. The cost per ship might be at least $90 million.

The Streetfighter would be a smaller, very fast ship (part of the more general Streetfighter concept), that could compete successfully with the enemy for control of coasts and littoral waters. These ships are envisioned as costing less than 10% as much as current Battle Force ships, while comprising more than 25% of the total number of surface combatants [that is at least 25 but no more than 50 units].

The President of the Naval War College, Admiral Art Cebrowski, and others such as Capt. Wayne P. Hughes, have advocated the deployment of larger numbers of smaller ships to operate in “harm’s way” in littoral waters. Cebrowski and Hughes talk of “tactical instability,” where a navy is unwilling to risk its ships because the fleet is constituted principally of small numbers of expensive ships. They propose “re-balancing the fleet” by supplementing the currently planned large surface combatants with the procurement of smaller ships."
(source Globalsecurity.org)

Well, this intent turned into two prototypes for a LCS that are rather fast frigates and cost hundreds of millions of $.
The Swedes meanwhile built their Visby corvette (photo) - much slower than the Streetfighter concept, but otherwise quite similar. I have a problem with the Streetfighter/LCS speed requirements anyway. Hughes attempted to make the argument for high speed in his book, but didn't convince me.

The question of many smaller and really affordable ships to balance the big ship fleet of the US Navy as well as for naval actions close to shore ("littoral combat", "brown water") is a popular discussion topic.

Most who discuss this don't seem to start at a FAC (fast attack craft) as basis. They're usually unwilling to shed much firepower in comparison to frigates.
The proposals of individuals (usually free of any real calculation of volumes and weights) often end up as mini AEGIS cruisers with the capability of an Álvaro de Bazán class frigate (5,250 ts full) in a corvette-sized hull (usually imagined as 1,500 to 3,000 tons ).

It would be possible to start at proven FAC designs, adding merely some ASW (anti submarine warfare) equipment as used in helicopters - but this approach doesn't seem to be enticing enough.


The basic tactical idea of Cebrowski and his staff was likely to build ships that are not valuable (and thus not capable!) enough to be targeted by a SSK (modern conventional submarine) or an elaborate air attack.
Such ships would get lost in major naval warfare (as is actually absolutely normal, too many people seem to have forgotten about this) without much loss of life - the crew would be small.

The desire to have a powerful ship (even though as small as possible) looks like an almost primitive instinct to me.
Power is actually NOT desirable for such a design.
Power costs money, thus reduces quantity - and turns the ship into a juicy target, probably even ruining instead of bolstering its survivability.

Attackers have to think twice whether they will spend their surprise effect and resources at sinking ships even if they cannot reduce the enemy's offensive potential by doing so.

It's always possible to add some offensive power, to mount better sensors or to add longer-ranged air defense, maybe a helicopter pad ... but the inability to settle with a low power unit inevitably leads to big ships - ships that cannot meet the demand for "many + cheap" units.


I already mentioned the approaches that use a FAC or frigate/destroyer as starting point for morphing a design into a "smaller" combatant to beef big ship-heavy fleets.

I've got a different approach
(the subject really kept me occupied for a while):

I kept my old decoy/CIWS small boat idea and mated it with the screening small ship idea as Cebrowski and Hughes (who btw wrote an interesting book).

My starting point was the German mine-weeping drone of the "Seehund" (seal) class. It's a proven drone that provokes and survives mine hits using acoustic and magnetic simulation equipment. That design weighs in at 100 tons and has no crew (can be manned, though).

This is what I would add:

- a radar jammer
(some missiles can home on the jamming and I would prefer them to home on this boat than on a frigate or larger ship)
about 200 kg

- several decoy launchers like SRBOC
(infra-red and radar decoys, possibly also acoustic decoys against torpedoes)
about 1,000 kg for 18 loaded SRBOC tubes

- a close-in weapon system against missiles, close aircraft and guided glide bombs
(to increase survivability and to exploit CIWS firepower far ahead of the real warship, also self-defence against very small surface targets like speed boats)
about 7,000 kg (if Vulcan Phalanx and a few RAM tubes were combined)

- basic ESM system
(to detect enemy radars and radio communications)
about 500 kg

- towed radar decoys
(really just a rubber dinghy with simple 90° radar reflectors)
about 100 kg

- a dipping sonar as used by helicopters
(to complicate enemy sub operations)
about 500 kg

- a lightweight multi-function radar, possibly one of the Sea Giraffe family
(to complicate enemy air operations and to support aerial surveillance radars)
less than 1,000 kg including mast and console

- an infra-red scanner for air search, this weighs almost nothing but is short-ranged
(to detect radar stealth objects in the air and for air search during radar silence)
about 50 kg

- two 324mm lightweight torpedoes /w tubes
about 800 kg

- 18 kts cruise speed
(in order to cruise with the fleet)
? tons for much stronger propulsion and electrical system

- a two-way datalink, involving satellite communications
(to make good use of all this with remote control)
about 200 kg

- volume & weight for a crew of about 6-12 (incl. emergency equipment)
? tons

The CIWS, cruise speed requirement and crew seem to cause the greatest addition of weight, but it looks as if such a boat could be restricted to 250 tons.

It's a pain in the ass of the enemy because of its scouting and deception capabilities. It's difficult to hit even though it has no strong SAM armament. It's not be part of the fleet's main strike capability.
It's useful, but the enemy would waste time and resources on its destruction. The purpose of defensive power of a fleet - buying time for the offensive power to do its job - seems to be served if the enemy attacks such small warships.
The enemy might choose to evade it - in that case it would aid the friendly defense by adding depth / early warning.
A nice dilemma.

A little bit larger and more capability (especially more offensive capability) would lead to a design similar to the Swedish Stockholm coastal corvettes (380 tons), the predecessors of Visby.


I began at a mine sweeping drone and moved up to FAC-sized craft, almost up to a coastal corvette. The end result fills a tactical niche instead of packing a big ship into a small hull. The actual tactical value and seaworthiness of such a small craft would need to be tested in experiments and maneuvers - it's impossible to determine for a single thinker.

Sven Ortmann

P.S.: Some sources tell about 1,200 tons as planned "Streetfighter" displacement.
I wasn't even able to find a line drawing or artist's impression for the Streetfighter concept, it seems as if it was primarily a discussion topic by the office for force transformation.
Admiral Cebrowski: R.I.P.
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5 comments:

  1. I'm glad to see you've kept up the pace and quality of articles on this blog. I like this concept of a small fast attack craft with ASW, AA(at least a vulcan or two), and some Anti-surface capability. This type of craft would be very effective as part of a screening force for the a larger fleet, locating and engaging the enemy before they can get close enough to strike the main fleet. I worry about the potential vulnerability of some of our navy's biggest ships. In the event of a major, long-term war, it would be much better to have a less top-heavy fleet, and to have a ship design that can be used for coastal defence and that can be produced quickly, cheaply, and in marginal shipbuilding facilities. It would be nice to somehow squeeze a helicopter pad on the ship, it would make it much more versatile and powerful. I might also want to up-gun the air defence a bit too. If it's going to be used against surface targets as well, it'd be nice to have a little more firepower. Of course this would make it bigger and more expensive, but something in the corvette range wouldn't be too unwieldy for this role.

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  2. The key problem that leads to all-big-ship navies is likely exactly this; the need for self-discipline among administrative leaders.

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  3. Sven,

    I've been thinking about small, unmanned vessels as well.

    My hangups are how do you manage mundane things like refueling and repairs during long ocean voyages, and especially in bad seas.

    I have a feeling a 25m vessel may just be too small to handle rough ocean transit. How slow will a task force have to go for these ships to keep up in SS5+?

    OTOH, they could be carried by a mothership which would also perform drone care and feeding.

    One parent craft I was considering for this role is the Arie Visser class Life Boat.

    http://www.habbeke.nl/arievisser.html

    It's an 18.8m, self-righting RHIB that can sail at 32kts for 16 hours straight. Presumably it could go further and longer at slower speeds.

    They claim it can sail in any weather. Being a rather beamy RHIB it should have a lot of excess buoyancy and stability.

    I would strip it down to its hull and propulsion (the "sea frame"), and line the deck with mount points for modular equipment. Maybe keep a small pilot house for optional manned use.

    A mothership would carrying many of these sea frames and a variety of modules for various purposes.

    A "normal" ASW sea frame configuration might include,

    - a 30mm Mk 38 MOD 2
    - a 15 rnd Netfires container
    - a lightweight towed array, VDS or active source (for a multi-boat multistatic system)
    - 2-4x lightweight torpedoes
    - surface search radar
    - EO/IR
    - sat & LOS coms

    Or you could change it out for a MIW kit, an AAW-Shooter kit with VL ESSM or AMRAAM, an AAW-Sensor kit with an air search radar like Sea Giraffe or TRS-3D, an SF kit with a modular cabin or seats.

    Smaller RHIBs just can't carry this kind of thing, and have limited endurance, range, seakeeping and ability to tow sonar arrays or MIW UUVs.

    Existing 11m RHIB USVs also can't carry a self-defense ASuW system along with their mission package.

    Having multiple means of communications is also vital. In a war, Satcom links are limited. Having capable LOS links that can talk to a UAV relay or warship may be critical.

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  4. How about a uav instead of a manned A/S helo to save mass & space?

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    Replies
    1. Less payload means less utility.
      Your UAV couldn't be capable of SAR or of ferrying supplies, ferrying personnel or landing some marines on a freighter for an inspection.

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