WN27, also known as World Navy 27, was a one-man submarine piloted by World Navy Captain Jacques Jordan.
Piloted by Captain Jacques Jordan, WN27 participated in a joint WN-WASP operation to test a WN underwater missile against the WASP flagship Stingray. It fired the missile at Stingray, and then returned to Marineville after finishing a series of promising tests.
The next day, Jordan piloted the submarine out alongside Stingray for continuation of the tests. Unfortunately for Jordan, some Aquaphibians boarded the ship and hijacked it while holding him at gunpoint. They forced him to fire the missile fully armed at Stingray, with the intent to destroy it and Captain Tempest. Fortunately, Stingray avoided destruction, and the Aquaphibians were subdued.
A disgraced Jordan later left Marineville in the submarine.
- The model's hull was built from a midget racing car kit turned backwards, with the conning tower in the driver seat.
- The model was later painted orange and had turbine parts added for reuse in the Thunderbirds episode "The Man from M15."