The Americans are creating a supersonic submarine with a speed of 5800 km/h

In January, Lockheed Martin and NASA unveiled the X-59 experimental aircraft, which is expected to fly 1.4 times the speed of sound (1,490 km/h) without producing an explosive sonic boom.
That aircraft should play a key role in the re-establishment of supersonic commercial air travel.

But the Americans are now working on a submarine that could travel up to three times faster than the X-59. Although it sounds incredible, it is theoretically possible to dive at these speeds. In 2016, Pennsylvania State University scientists began developing a revolutionary submarine capable of reaching supersonic speeds.

They concluded that a simple solution to overcoming drag underwater was to create a bubble. A technology called supercavitation will submerge the submarine in a bubble of air to reduce water resistance.

This technology, surprisingly, is not new. It was developed by the Soviets during the Cold War period for the 370 km/h Shakval torpedo, making it much faster than any other conventional torpedo.

But the Americans are not the only ones working on creating a supersonic submarine. Harbin Institute of Technology (China) is also working on a supersonic submarine that relies on supercavitation.

In theory, this technology could help the submarine reach supersonic speeds underwater, up to an incredible 5,800 km/h. If developed, the supersonic submarine would cut the travel time from New York to London to just 50 minutes.

Furthermore, the 8,270 km between San Francisco and Tokyo can be covered by the submarine in just 90 minutes.

However, we should not expect the supersonic submarine to revive any time soon as there are some serious challenges along the way.

Conventional propellers will never be able to help propel the ship to such speeds. The submarine is supposed to have a powerful underwater rocket engine that has not yet been developed.

Then there are steering issues as traditional rudders won’t work in the bubble and at those speeds.

Which submarines are the fastest?
Established reports indicate that only a few submarines are capable of speeds in excess of 30 knots (56 km/h). The experimental USS Albacore reached a speed of 33 knots (61 km/h) in 1965.

Furthermore, in 1968 it was determined that a Soviet submarine of the Studeni class reached a speed of 31 knots (57 km/h). In response, the United States Navy developed the Los Angeles-class submarine with a speed of 30–32 knots (56–59 km/h).

The Russian Akula-class ship can reportedly travel underwater at a speed of 35 knots (65 km/h). Its predecessor, the Alpha class, could achieve short bursts of speed of 40–45 knots (74–83 km/h) while underwater.

There are also claims that the Soviet twin-propeller submarine K-222, with an inner and outer titanium hull, reached 44.7 knots (83 km/h) during trials in 1969.