As Australia's competitive evaluation process continues there are increasing options in terms of:
- vertical multi-purpose locks (VMPLs) (most developed by the US and there called "Virgina Payload Tubes (VPTs)") and
- horizontal multi-purpose locks (HMPLs) that are being developed by Saab-Kockums and TKMS-HDW. Saab may fit a 1.5 meter HMPL (which Saab calls a "Multiimission Portal") to the A26 submarines that Saab is building for the Swedish navy.
VMPL and HMPL's are being built to potentially carry:
- extra torpedos
- extra anti-ship missiles
- extra land-attack missiles (like the Tomahawk)
- diver swim out cell
- diver delivery vehicles
- an unmanned underwater vehicle (UUV) too large to fit in torpedo tubes, or
- UUV that cannot be reversed back into torpedo tubes.
The proposed design of the 1,000 ton TKMS Type 210mod displays an HMPL (a grey tube) more distinctly. The HMPL sits below what appear to be 4 x 400mm (Baltic small style) torpedo tubes.(Courtesy TKMS website)
The Saab Australia site image can be expanded here. Note large looking (perhaps 1.5 meter) HMPL or "Multimission Portal" (a Saab registered trademark).
The Saab site description indicates - "Saab's A26 [submarine] design includes a new innovative 6m x 1.5m Multimission Portal flexible payload capability with a lock system in addition to its conventional torpedo tubes. The lock system makes it easy for commandos to enter and exit the boat, and is large enough to allow the launch and retrieval of Unmanned Underwater Vehicles. UUVs are expected to play a larger role in future submarine warfare. They can already provide advance surveying and sensing capabilities, and their modification toward a combat role is a certainty. This will likely begin with coordinated decoying tactics, but UUVs are expected to graduate to active combat capabilities before the A26 leaves service."
A UUV exiting an A26 submarine via its Multimission Portal (Courtesy Saab A26 website).