Does a caterpillar drive exist?

Does a caterpillar drive exist?

Modern Military

Instead of pushing water through a tube by pushing water through a magnetic field, this drive system is something like a linear motor, moving a piston back and forth. The piston contains a valve, and when the piston moves one way, it sucks water in. When the piston moves in the opposite direction, it pushes water out. Source: A Caterpillar Drive That Actually Looks Like A Caterpillar | Hackaday

The “Red October” caterpillar drive is a fictional propulsion system featured in the 1990 novel “The Hunt for Red October” by Tom Clancy, as well as its 1992 film adaptation. In the story, the caterpillar drive is a revolutionary propulsion system that allows a submarine to move almost silently, making it virtually undetectable by other vessels.

While the Red October’s caterpillar drive is purely fictional, there have been some real-world examples of caterpillar propulsion systems in use.

For example, in 2015, the Japanese shipping company NYK Line launched the MV NYK Blue Jay, a large car ferry that uses a “caterpillar” propulsion system to move through the water.

This system is not the same as the fictional caterpillar drive in “The Hunt for Red October,” however. According to the book:

Moreover, the Red October’s caterpillar drive consists of two main components: a turbine and a magnetohydrodynamic (MHD) pump. The turbine becomes driven by the submarine’s nuclear reactor. And then rotates at high speed to create a flow of water through the MHD pump.

The Sun is an MHD system that is not well understood, possibly because of the simplifications of plasma physics required in this framework.
NASA/SDO – NASA image of the day: Sun’s Quiet Corona

The MHD pump consists of a series of magnets and electrodes arranged in a circular array. As the water flows through the pump, it is ionized by the electrodes, creating a stream of charged particles. These particles are then accelerated by the magnetic fields generated by the magnets, creating a powerful jet of water that propels the submarine forward.

Gentle Leader

Instead, the MV NYK Blue Jay’s caterpillar drive uses two large pods attached to the sides of the ship that can rotate 360 degrees. These pods contain electric motors that power the ship’s propellers and can be moved independently of each other, allowing for greater maneuverability and control.

Head office of NYK Line (日本郵船) at Marunouchi, Chiyoda, Tokyo, Japan

A Magnetohydrodynamic (MHD) drive is a propulsion system that works by using the interaction between a magnetic field and an ionized fluid (plasma) to generate thrust. In a MHD drive, an electrically conductive fluid, such as seawater, is passed through a magnetic field. As the fluid flows through the field, it generates an electric current, which in turn generates a magnetic field that interacts with the original field. This interaction creates a Lorentz force, which propels the fluid and generates thrust.

The basic components of an MHD drive include a flow channel, a magnet system, and an electrode system.

The flow channel is a duct or pipe through which the conductive fluid flows. The magnet system generates a magnetic field that is perpendicular to the direction of fluid flow. The electrode system includes electrodes that are in contact with the fluid and provide an electrical current to ionize the fluid.

When the conductive fluid flows through the flow channel, it passes through the magnetic field generated by the magnet system.

Magnet Powered Submarine

As the fluid flows through the field, it becomes ionized by the electrodes, creating a plasma. The plasma, which is now electrically conductive, interacts with the magnetic field to generate a Lorentz force that propels the fluid and generates thrust.

Schematic view of the different current systems which shape the Earth’s magnetosphere
David P. Stern, 1994: “The art of mapping the magnetosphere” (Journal of Geophysical Research, doi:10.1029/94JA01239);

The efficiency of an MHD drive depends on a number of factors, including the strength of the magnetic field, the speed and density of the fluid, and the degree of ionization. Higher magnetic fields and greater fluid speeds generally lead to higher levels of thrust. However, the degree of ionization also plays a critical role in determining the efficiency of the system. If the fluid is not sufficiently ionized, the Lorentz force generated by the system will be weak and the thrust generated will be low.

MHD drives have a number of potential advantages over other types of propulsion systems, including their high efficiency and low noise levels.

However, they also have some significant drawbacks, including their high power requirements and the difficulty of controlling the ionization process. As a result, MHD drives are still largely experimental and are not currently used in any practical applications.

As for the United States Navy, they have been developing a new type of propulsion system called the Virginia-class submarine, which incorporates a form of caterpillar drive. This system, known as the Virginia Payload Module (VPM), replaces the traditional gear shift used in older submarines with an electric motor that can turn the submarine’s propeller blades more quickly and efficiently.

US Navy 040730-N-1234E-002 PCU Virginia (SSN 774) returns to the General Dynamics Electric Boat shipyard.jpg
Groton, Conn. (July 30, 2004) – The nation’s newest and most advanced nuclear-powered attack submarine and the lead ship of its class, PCU Virginia (SSN 774) returns to the General Dynamics Electric Boat shipyard following the successful completion of its first voyage in open seas called “alpha” sea trials. Virginia is the Navy’s only major combatant ready to join the fleet that was designed with the post-Cold War security environment in mind and embodies the war fighting and operational capabilities required to dominate the littorals while maintaining undersea dominance in the open ocean.

The VPM also allows for greater flexibility in terms of how the submarine’s weapons and other equipment are stored and deployed!

As a result, making it a significant advancement over older submarine designs. However, it is important to note that the VPM is not a true “caterpillar drive” like the one depicted in “The Hunt for Red October,” as it does not allow the submarine to move silently or avoid detection by other vessels.

The Columbia-class submarine is a new class of nuclear-powered ballistic missile submarines that is currently under development by the United States Navy. These submarines are designed to replace the aging Ohio-class submarines, which have been in service since the 1980s.

One of the key features of the Columbia-class submarines is their new propulsion system, which will eliminate the noise produced by metal gearing engaging and disengaging.


Graphic artist concept, 2012

Instead of using a mechanical drive system that relies on gears to transmit power from the submarine’s nuclear reactor to the propellers, the Columbia-class submarines will use electric shaft motors.

Cutaway image
CAPT William J. Brougham, USN – PMS397 Program Manager – NAVSEA – “Document: Ohio Class Replacement 2014

Electric shaft motors are essentially electric motors that are directly coupled to the submarine’s propellers. This eliminates the need for gears, which can produce a significant amount of noise when they engage and disengage. The electric shaft motors will be powered by the submarine’s nuclear reactor, which will generate electricity that is used to drive the motors.

The elimination of the noise produced by metal gearing engaging and disengaging is a significant improvement in terms of the submarine’s stealth capabilities. It will make the Columbia-class submarines much quieter than their Ohio-class predecessors, which are already some of the quietest submarines in the world.

In addition to the electric shaft motors, the Columbia-class submarines will also feature a number of other advanced technologies designed to enhance their stealth and survivability. These include a new quieting system that reduces the noise produced by the submarine’s pumps and other machinery, as well as an advanced sonar system that is designed to detect and track other submarines and surface ships at long range.

Does a caterpillar drive exist?