With supercavitating torpedoes, such as the VA-111 Shkval, come the promises of unparalleled speeds and lethality that will revolutionize underwater combat. Developed during the Cold War era, the Shkval torpedo promised unprecedented speed of up to 200 knots through the use of the supercavitation phenomenon to outpace traditional underwater armaments.
Supercavitation occurs when water is vaporized into gas, creating a bubble that envelops the torpedo, drastically reducing drag and allowing it to travel at high speeds. However, the breakthrough of this technology creates huge setbacks regarding guidance and control. Traditional torpedoes use control surfaces that interact with water in a similar way as the wings and rudder on an airplane. However, supercavitating torpedoes cannot extend such surfaces from outside their protecting bubble without risking its collapse, thus allowing only straight-line trajectories and maneuverability losses.
The Shkval, with its rocket engine, solves the drag problem by venting hot exhaust through its nose, flash-vaporizing water into steam and creating a gas bubble. That enables the torpedo to maintain its tremendous speed but also limits the ability of the torpedo to make turns. Early models of the Shkval featured very basic guidance systems, adequate for simple, straight torpedo runs. With the nuclear warheads they would have carried, precision was less an issue than speed.
Its speed is indeed phenomenal, but it has one serious deficiency: its noise levels. The gas bubble and the rocket engine both generate enough noise to give their position away. Of course, its speed might be able to neutralize the target before it could respond, which is a tactical plus.
The U.S. Navy has been working on its supercavitating torpedoes since 1997, but nothing worthwhile has been put into service. The requirement for the Navy to turn, identify, and home into targets is considered beyond the existing supercavitating designs. Incidentally, the Russian submarines are reportedly the only ones fitted with updated versions of the Shkval fitted with conventional warheads. Russia offers an export version called the Shkval E, and Iran reportedly has developed a similar torpedo, the Hoot that analysts consider a reverse-engineered Shkval.
The legacy of Shkval finds a continuation in a modern conceptualization of naval tactics since the speed and uniqueness of this technology challenge traditional thinking about undersea warfare. In this respect, supercavitating torpedo development and deployment is expected to become the leading factor in possible future maritime conflicts.