A26 Blekinge Submarine: The World’s First Fifth-Generation Conventional Submarine Explained
When Saab Kockums began deliveries of the A26 Blekinge, it claimed a title that defence analysts had been debating for years: the world’s first fifth-generation conventional submarine. The label is contested — as such classifications always are — but the hardware supports an argument. Stirling air-independent propulsion enabling over 45 days submerged without surfacing, a dedicated special-operations portal for diver and UUV deployment, and a seabed-warfare module for critical infrastructure operations represent a qualitative step beyond the diesel-electric boats that dominated the Cold War. Poland’s 2025 order for three A26s, driven by Baltic security demands in the aftermath of Russia’s full-scale Ukraine invasion, is the most commercially significant submarine contract in Scandinavia in a generation.
Kockums: From Independence to Saab
Kockums was founded in 1840 in Malmö. Its submarine division built successive generations of Swedish boats — the Draken, Näcken and Västergötland classes — while pioneering Stirling AIP technology in the 1980s and 1990s. In 1999, the German firm HDW (later ThyssenKrupp Marine Systems) acquired Kockums, creating an awkward situation in which Sweden’s most sensitive naval technology resided in foreign hands. In 2014, the Swedish government brokered Saab’s purchase of Kockums, restoring domestic control and enabling the A26 programme to accelerate under a Swedish industrial champion.
Stirling AIP: The Underwater Endurance Engine
The A26’s most operationally consequential feature is the Kockums Stirling MkV AIP system. A Stirling engine operates on an external heat source; in the submarine application, that source is the controlled combustion of diesel fuel with stored liquid oxygen (LOX). The engine produces electricity without consuming atmospheric oxygen, meaning the boat can remain fully submerged as long as its LOX and diesel reserves permit. On AIP propulsion alone, the A26 can remain underwater for approximately 18 days; combining diesel-electric and AIP endurance produces a total submerged capability exceeding 45 days. In the Baltic Sea — where Russian anti-submarine warfare (ASW) assets are permanently present — 45 days of silent, submerged operation represents a significant survivability advantage.
Multi-Mission Portal (MMP)
The A26 incorporates a 1.5-metre-diameter Multi-Mission Portal in the bow section. While the submarine is submerged, the MMP allows the safe egress and ingress of special-operations personnel, swimmer delivery vehicles and unmanned underwater vehicles (UUVs). This capability transforms the A26 from a purely strike/surveillance platform into a covert force-projection asset: it can insert special forces into a hostile coastline without surfacing, maintaining its acoustic and electromagnetic silence throughout.
Technical Specifications
| Parameter | Value |
|---|---|
| Length | 66.1 m |
| Beam | 6.75 m |
| Displacement (submerged) | ~2,100 tonnes |
| Propulsion | Diesel-electric + 4× Stirling MkV AIP |
| Maximum Speed (diesel) | 20 knots |
| Silent Speed (AIP) | ~6 knots |
| AIP Endurance | ~18 days |
| Total Submerged Endurance | 45+ days |
| Standard Crew | 26 |
| Special Operations Capacity | +35 additional personnel |
| Heavy Torpedo Tubes | 4× 533 mm (Torped 62) |
| Light Torpedo Tubes | 2× 400 mm (Torped 47) |
| UUV Deployment | Yes (MMP) |
| Poland variant VLS | 18× Tomahawk |
| Combat Management | 9LV CMS |
Operators and Orders
| Country | Quantity | Status |
|---|---|---|
| Sweden | 2 (Blekinge + Skåne) | Under construction |
| Poland | 3 | Contract signed; ~2030 delivery target |
The Polish contract is the programme’s commercial breakthrough. Warsaw chose the A26 specifically for Baltic operations, and the Polish variant will carry a vertical launch system (VLS) configured for Tomahawk cruise missiles — a capability that no other A26 operator has requested and that significantly extends the platform’s strategic reach. Poland’s defence procurement is being shaped by the recognition that maritime denial in the Baltic is as important as land-based deterrence on its eastern flank.
Strengths
- 45+ day submerged endurance — unmatched in the conventional submarine category
- Multi-Mission Portal for covert special-operations insertion
- Seabed warfare capability for critical underwater infrastructure protection and operations
- Polish VLS option for Tomahawk — long-range land-attack capacity
- Comprehensive multi-spectrum signature management
Limitations
- No combat record — an entirely new platform
- LOX storage and Stirling engine maintenance demand specialised technical expertise
- Kockums’ limited production capacity means extended delivery timelines for large orders
Competitive Landscape
| System | Origin | Length | Displacement | AIP | SOF Capability |
|---|---|---|---|---|---|
| A26 Blekinge | Sweden | 66 m | 2,100 t | Stirling | Yes (MMP) |
| Type 212CD | Germany | ~64 m | ~1,800 t | Yes | Limited |
| KSS-III | South Korea | 83.5 m | 3,700 t | Stirling | Yes |
| Soryu class | Japan | 84 m | 4,200 t | Stirling | No |
| S-80 Plus | Spain | 80.8 m | 3,000 t | MESMA | Limited |
Why It Matters for Turkey
The Turkish Navy operates six Type 209/1400 and six Type 214 submarines. The domestic submarine programme, MÜRTED, is in concept and preliminary design under SSB coordination. The A26 provides a useful design reference: its Stirling AIP architecture, modular mission concept and seabed-warfare capability define what the next generation of Turkish submarines should aspire to deliver. The 45-day submerged endurance, in particular, is directly relevant for operations in the Eastern Mediterranean and Black Sea, where Turkish submarines must operate against ASW-capable adversaries.
Bottom Line
The A26 Blekinge is the most consequential advance in conventional submarine design in 20 years. Poland’s contract, driven by Baltic security imperatives, confirms that the market for advanced AIP submarines is expanding rather than contracting. For Turkey’s MÜRTED programme, the A26 sets the performance bar: Stirling AIP, special operations integration, and seabed-warfare capability are the baseline requirements of the 2040s underwater battlespace.
