SSN Design Challenge

[Lebroba]

there we go, oh... seems I've forgotten the rocket motors

What would be the point of a super cavitating submarine?

[Razgriz BSG-27]

You know, I'm not entirely sure I think it would be most useful for torpedo evasion, as one can rig for supercavitation in about two minutes, which is basically closing the cover for the impeller and opening the rocket vents, getting everyone aboard , er secured and reeling in all you wires, and towed arrays. Also high speed transit undetected by satellite surveillance, now anything with a sonar will here you, but te odds that it or it's weapons could catch you are very slim, unless they happen to have Shkval's embarked, now on the subject of maneuvering, how long it would take you to slow down is something I won't even touch for the sake of my own dignity, but for pitch and yaw, those airbrake looking things are for course correction( I have made the error of not showing them in the correct position for supercavitation) as they hold the bubble around the hull just ever so slightly , you would move one of the four in which ever direction you wanted to go and it would reform the bubble in such a way as to create drag and you would turn , however this would be almost certainly computer controlled because if you weer off by even an inch you would run your boat into the wall of it's own bubble and break the pressure-causing your bubble to collapse and a bare hull (Slicked by the lubricant but for all intents and purposes bare) hitting the water at that speed (around 70-80 knots) would ball it up or disintegrate it ,and the sudden stop would eviscerate anything on the inside.
SO in-short my idea is impractical of little strategic value and dangerous (per usual)

but I make it a policy of mine (since I have no real background or experience in naval architecture, however I have a rudimentary understanding of tactics) to inject something different or interesting into my designs, even though it tends to end up repetitive or useless-sometimes even counter productive (In the case of the mixed boomer attack boat)

[acelanceloet]

I think you will destroy the sub if you do so. I am not entirely sure, but the amount of pressure on your hull seems to be enormous to me.

[Razgriz BSG-27]

"Supercavitation is the use of cavitation effects to create a bubble of gas inside a liquid large enough to encompass an object travelling through the liquid, greatly reducing the skin friction drag on the object and enabling achievement of very high speeds. Current applications are mainly limited to projectiles or very fast torpedoes, but in principle the technique could be extended to include vehicles"

"A supercavitating object uses cavitation in a larger and more sustained manner than with the (typical) ship's propeller (hence the name supercavitation). A supercavitating object's main features are a specially shaped nose, usually flat with sharp edges, and a streamlined, hydrodynamic and aerodynamic shape. When the object is travelling through water at high speeds, the flat nose deflects the water radially outward at speeds such that there is a tremendous drop in pressure aft of where the water passes over the sharp edge of the periphery of the nose, causing a cavitation bubble that will generally close in behind the object. The bubble will persist, travelling with the object, forming at the nose and closing in behind. If the resulting cavity is not large enough, it may be extended by internally generating additional gas to inject into the cavity. The result is that the only portion of the object in direct contact with the water is the nose, and skin friction drag is substantially reduced"

Now the nose bit I forgot when I drew this but, I shall amend the drawing as such

[Razgriz BSG-27]

Updated:

[acelanceloet]

for an object this size, you will need additional gas to be pushed at the nose, otherwise you need to go for an high speed before you use supercavitation.
also, it is very hard to make your nose with an working shape (which you don't have now) and let it keep strength, so your sonar and weapons will not be able to go into the forward 10-15% of your ship.

also, what are those weird hatches and openings in your stern section?

also note that you cannot control nor see anything when you super-cavitate.

all in all, I think this is an bad idea.

[Razgriz BSG-27]

Mentioned above when I tried to explain what it's good for, It is infact a bad idea




Also my two bits on challenges (not like my opinion matters)
I think that we should have some challenges where a very specific goal needs to be met, say with submarines torpedo evasion (evading after the torpedo has been fired), or for surface warships, a combination of roles into one vessel, but have these things be entirely serious, what comes to mind when I think of these type of challenges is DARPA (which as we all know comes up with some off the wall problems&solutions)

[BrockPaine]

Renommée-class Nuclear-Powered Guided-Missile Submarine
Length: 111.25 m (365 ft); 112.25 m (368.2 ft) (second pair)
Beam: 11 m (36 ft)
Draft: 8.3 m (26.9 ft)
Displacement: 6,000t surfaced - 7,000t submerged
Propulsion: Pressurized Water Reactor
Speed:
- 30+ knots submerged
- 18 knots surfaced
Test Depth: 250 m (820 ft)
Crew: 131 men
Armament:
- 4 x 53cm (21") torpedo tubes with F17 Mod 2 torpedoes and Exocet SM39 missiles (~24 reloads carried)
- 14 x VLS tubes for Makaire antiship missiles (Renommée and Le Fantasque); 12 x VLS tubes (Surcouf, and Casabianca)
Ships in Class:
- Renommée (1980)
- Le Fantasque (1981)
- Surcouf (1984)
- Casabianca (1985)

As the French Marine Nationale entered the 1970s, the first Redoubtable class ballistic missile submarine was well along in construction, with more vessels planned. Although France had chosen to pursue nuclear-powered ballistic missile submarines as their first priority, interest in a dedicated nuclear-powered attack submarine grew among the submarine force (Forces Sous-marines). An upsized nuclear-powered variant of the Agosta class diesel-electric submarines was tendered by DCNS, with the anticipation that these small SSNs, the smallest combat types in the world, would be suitable to both the Mediterranean and the Atlantic Oceans. However, a much larger type, similar in many ways to the American, British, and Soviet submarines entering service at the time, was likewise offered. The Forces Sous-marines felt the nation would be better served by this larger, faster, and more capable vessel. The final design, started in 1974 and presented to the MN in 1976, adopted a number of intriguing nods to Soviet designs such as the "Charlie" class (Project 670 Skat).


First design study for a missile-launching nuclear attack submarine.

Six submarines were ordered, but only four vessels were laid down. The first pair, Renommée and Le Fantasque, were essentially identical in all respects. The second two boats, Surcouf, and Casabianca, had a few subtle differences; these two boats were deemed to be a sub-class.


First pair of boats, as constructed.


Second pair of boats, as armed in 1994.

For the first time, the French designers adopted a more streamlined hull form, similar in many ways to the American Sturgeon (SSN-637) and Los Angeles (SSN-688) hull forms. This allowed the boats to achieve over thirty knots submerged, with figures as high as thirty-six knots quoted among popular media. Despite this, the French rarely operated the boats faster than twenty-five knots until after their mid-life refit, as the Renommée and Le Fantasque suffered from excessive reactor noise at those speeds. This was the result of difficulties with altering the Redoubtable's reactor design for higher power and speeds. Many of these problems were fixed in Surcouf, and Casabianca prior to their commissioning, however, and Renommée and Le Fantasque both received refits of new reactor components to bring them up to standard.

Renommée's most potent capability was the vertically-launched sea-skimming Makaire antiship missile. Developed in tandem with the Exocet, the Makaire ("Marlin") tipped the scales at 1,205 kg. With a range of 330km, a speed of 815 knots (Mach 1.2), and a 200 kg (441 lb) warhead, the Makaire seemed to be the West's equivalent of the powerful submarine-launched ASMs in use by the Soviet Union. The missile was developed by Aerospatiale in conjunction with the Délégation Générale pour l'Armement (DGA) and entered service in 1981, four months after Renommée. The French banked on their experience with submerged launch of ballistic missiles to refine the Makaire's design.

The first submarine in the class, Renommée, was laid down in December 1976 and entered service four years later, in 1980. The Makaire missiles which formed the greater part of her armament, however, did not enter service until 1981, only two years before the slower, but otherwise comparable Tomahawk TASM entered service with the US Navy.

Unlike the first pair of boats, Surcouf and Casabianca were completed to a slightly different design. Along with improvements in reactor cooling and silencing, these two boats had only twelve VLS tubes (down from fourteen) in exchange for a swimmer lock-in-lock-out chamber and docking collar for a swimmer delivery vehicle. The second pair of submarines were also one meter longer.

Due to their operational similarities to the Soviet SSGNs, the Renommée class alarmed many Western strategists particularly in the United States, as the adoption of the Makaire implied, in their minds, an expected opposition force such as a NATO carrier battlegroup. The French Navy, by contrast, saw little strategic difference between the Exocet or Harpoon, launched from torpedo tubes, and the vertical-launched Makaire. The successful Argentine use of the "little brother" Exocets in the Falklands War similarly heightened British worries about the more potent Makaire being sold to potentially-hostile states. US intelligence documents leaked in 2010 reveal high-level speculation that the Renommée class and the Makaire antiship missile were pushed ahead both as a boost to French prestige and a way to signal their independence from NATO policy.

Based at Ile Longue with the strategic Force de Frappe, the Renommée and her sisters formed the escadrille des sous-marins nucléaires d'attaque (Nuclear Attack Submarine Squadron). In 1982, Renommée was at sea when Argentine forces invaded the Falklands. According to popular rumor, the Royal Navy temporarily loaned the submarine and her French crew for participation in the Falklands War, and her supposed presence in the South Atlantic caused the retreat of Argentine naval forces. Both the British and French governments unequivocally deny that such an event ever took place, and records show that the Renommée returned to Ile Longue by May 3rd. Rumors of the submarine's supposed loan were recorded by Argentine naval staff during the month of April, but rejected as a likely ploy by British intelligence.

All four of the submarines made regular appearances in NATO wargames held in the Atlantic Ocean, at the request of the United States. As they resembled Soviet SSGNs in many ways, the Renommées often played the role of hostile Russian submarines as "Red Force". These exercises often tested the French against Los Angeles and Trafalgar class boats operating in carrier escort missions. High-speed maneuvers were often required to intercept the carriers, but at these high speeds, Renommée and Le Fantasque were blind and vulnerable. British submariners believed the quieter Surcouf and Casabianca, however, were among the toughest opponents faced in wargames, and noted "below fifteen knots, Surcouf is as quiet as modern bomber (SSBN)". The French improved their skills substantially during these exercises, and in 1988, Le Fantasque gained the satisfaction of "sinking" USS Enterprise.

In 1988, Renommée received a refit to improve her silencing and modify her vertical missile tubes to fire the latest variant of the Makaire missile, the Tencendur. Although not supersonic like the original Makaire, the Tencendur was capable of land attack. Le Fantasque was upgraded in 1990, while Surcouf and Casabianca did not refit until 1994.

In 1991, the Marine Nationale sent Le Fantasque, armed with Tencendur missiles, to participate in Opération Daguet, the liberation of Kuwait. Le Fantasque joined American and British submarines in launching attacks on targets within Iraq. This was the only time any of the Renommée class fired missiles in anger. Renommée herself was later deployed to the Persian Gulf, but arrived after the end of active hostilities, and never fired her payload of Tencendurs. In 1993, Surcouf briefly participated in Operation Sharp Guard, the NATO blockade of Yugoslavia; this mission was short-lived, as submarines were not very widely used in this operation.

By the end of the 1990s, it was clear the Renommée class was aging and would require replacement within the next ten to fifteen years. Design work therefore started on a replacement class, which would appear in 2014 as the Suffren.




Side-notes:
- Hull dimensions are based on the Los Angeles class attack submarines, as they fit the specifications (barely) and I wanted to get some reasonable specifications off a historical submarine.
- I chose a sorta-SSGN because I've always loved the idea of the Soviet Charlies and Oscars. Giving something similar to the French Navy required a bit of handwaving, at least on the strategic front.
- In this theoretical alternate universe, the four Renommées replace the six Rubis class, and are based in Brest rather than Toulon.
- I considered, like the Rubis, starting with a sort of bluff-bowed SSN (like the bow of Redoubtable) and then streamlining it in a pseudo-Amythest upgrade. I finished a doodle as a sort of early "proposal".
- Please pardon my long-winded storytelling penchant. I was tempted to let the drawing stand on its own, but meh.
- Considered making coats-of-arms for all four of the boats, but I think that was more trouble than I wanted to get into this week...
- From the French, because not enough people pay much attention to one of the more interesting navies in the world...
- I've simultaneously been doodling on another potential entry, so you may see another sub (or group of subs) from me later.

[Hood]

Brock,
Nice to see you active on these boards again!
Excellent work, those subs look plausible enough to be real. I like the 1970 Design Study too, it looks very much like an enlarged Agosta and strongly reminds me of Redoubtable. The Makaire is an interesting AU weapon too. Don't worry about a long backstory, a good backstory can explain more than a simple picture sometimes can, and shows the level of depth needed for a decent AU design.

[Colosseum]

Now THAT is some nice work!