Here’s why when a submarine launches an SLBM, it never gets wet, even though it is fired from under water

Here’s why when a submarine launches an SLBM, it never gets wet, even though it is fired from under water

By Dario Leone
Oct 29 2022
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When a submarine launches the SLBM, it never gets wet, even though it is fired from under water.

The UGM-133A Trident II, or Trident D5 is a submarine-launched ballistic missile (SLBM), built by Lockheed Martin Space in Sunnyvale, California, and deployed with the American and British navies. It was first deployed in March 1990, and remains in service. The Trident II Strategic Weapons System is an improved SLBM with greater accuracy, payload, and range than the earlier Trident C-4. It is a key element of the US strategic nuclear triad and strengthens US strategic deterrence.

Modern SLBMs like the UGM-133A Trident II are closely related to intercontinental ballistic missiles (ICBMs), with ranges of over 5,500 kilometres (3,000 nmi).

‘Both types of missile are hypersonic, have been for more than 50 years,’ Anthony Dagostino, Cavalry Scout at U.S. Army, says on Quora.

He continues;

‘Far more impressive, when a submarine launches an SLBM like the Trident II, it never gets wet, even though it is fired from under water. The system uses compressed gasses that encapsulate the missile as it rises to the surface. This bubble protects the missile from seawater during the ascent. Only after breaching the surface does the rocket motor kick in, launching the dry nuclear tipped ballistic missile on its journey to points only known to those on the short list of knowledge regarding the exact coordinates of the warheads.

‘Here’s how the system works;

‘First, the Trident II is ejected by steam. A tiny amount of solid rocket fuel is ignited, flash boiling water in a tank, which literally pushes the missile out of the launch tube with enough force to cause the missile to completely break the water’s surface. When the missile exits, onboard sensors detected the lost momentum by gravity, igniting the first stage rocket motor.

Here’s why when a submarine launches an SLBM, it never gets wet, even though it is fired from under water
PACIFIC OCEAN (Mar. 26, 2008) An unarmed Trident II D5 missile launches from the Ohio-class ballistic missile submarine USS Nebraska (SSBN 739) off the coast of California. The test launch was part of the US Navy Strategic Systems Program’s demonstration and shakedown operation certification process. The successful launch certified the readiness of an SSBN crew and the operational performance of the submarine’s strategic weapons system before returning to operational availability. (U.S. Navy photo by Mass Communication Specialist 1st Class Ronald Gutridge/Released)

‘Additionally, each missile is pressurized by nitrogen internally.

‘This is the copy/paste from Wiki….

“The missile is pressurized with nitrogen to prevent the intrusion of water into any internal spaces, which could damage the missile or add weight, destabilizing the missile.”

‘This is yet another marvel of modern engineering!

‘Each missile contains multiple warheads, each capable of many times more destruction that both bombs used on Japan in WWII. A single US submarine, or Boomer, is itself capable of wiping one of the greatest threats, either Russia or China, off the map with a full salvo. Not every square inch of soil, or even every military base, but enough cities would be totally wiped out, including command and control centers that contain the chain of command and their capabilities to connect and coordinate the military. It would be a headless state, with no communications, basically the military would be fighting blind and probably unable to work with any cohesion.’

Dagostino concludes;

‘Thank God we have very capable boomers, the true first strike and last strike silent killers. They cut the warning time down from 30+ minutes, to well under 15 minutes, varied upon location and target range.’

Here’s why when a submarine launches an SLBM, it never gets wet, even though it is fired from under water
On Jun. 2, 2014 a UGM-133A Trident II ballistic missile is launched from the U.S. Navy Ohio-class ballistic missile submarine USS West Virginia (SSBN-736) during a missile test at the Atlantic Missile Range. The test flights were part of a demonstration and shakedown operation, which the U.S. Navy used to certify a submarine for deployment after a major overhaul. The missiles were converted into test configurations with kits containing range safety devices and flight telemetry instrumentation.

Photo credit: U.S. Navy


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Dario Leone

Dario Leone

Dario Leone is an aviation, defense and military writer. He is the Founder and Editor of “The Aviation Geek Club” one of the world’s most read military aviation blogs. His writing has appeared in The National Interest and other news media. He has reported from Europe and flown Super Puma and Cougar helicopters with the Swiss Air Force.

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