Fire and forget

Torpedoes are a lot smarter than they used to be.

Originally, torpedoes weren’t too bright. They went where they were aimed, but couldn’t change course to follow a target. Later, sonar let them home in on a ship’s acoustic signals. That made them a little smarter, but they could be fooled by ship-mimicking signals.

In the 1980s, the Soviets brought out a torpedo that shot to the head of the class. Instead of looking for a ship, it uses upward-looking sonar to detect a ship’s wake. When it finds one, it zigzags from one side of the wake to the other until it reaches its target. The ship can’t take evasive action because wherever it goes, its wake follows. And because the torpedo is not tracking the ship’s noise, it can’t be diverted by phony ship-sounds.

Now, the U.S. Navy has a potential defense against this threat: an even smarter torpedo. Designed at Penn State’s Applied Research Laboratory, the Countermeasure Anti-Torpedo Torpedo, or CAT, is part of a defense system that can find and destroy a wake-homing torpedo. When a sensor array towed behind the ship detects an incoming threat, the CAT is launched. From then on, it’s on its own — “fire and forget,” says acoustics scientist Russell Burkhardt, director of ARL’s Undersea Systems Office.

“It goes out with its own sensors, searches, determines its own targeting, and makes decisions on how to maneuver,” says retired Naval officer Gary Watson, who has managed the CAT project for the past year. “The level of technology in the vehicle, nose-to-tail, is light years ahead of other torpedoes in our fleet. This is probably the smartest torpedo that’s ever been produced.”

Perhaps as impressive as the torpedo itself is the way it was developed — and how fast ARL got it into the water.

The Lab had already done some work on an anti-torpedo torpedo when, in December 2011, Chief of Naval Operations Admiral Jonathan Greenert gave them the full go-ahead on the project — with a catch.

“He challenged us to deploy this within roughly 24 months,” says Burkhardt — which meant building and testing a prototype themselves rather than having the Navy put it out for bids by industry. “We had to finish our design, then go through all of the testing that has to be done to prove that the weapon is safe for the sailor,” says Watson.

That urgency drove many of the innovations in how the vehicle was made, such as using simulation-based design to test and refine their ideas. “Simulations allow you to quickly assess a design without building it and testing it in water, which can be very expensive and take time,” says Burkhardt.

Simulations also made it possible to design all the sections of the torpedo — each carrying different components such as the power supply or navigational instruments — independently. That meant the sections could all be worked on at the same time, rather than following the usual, more time-consuming process of working on one at a time. If one section was ready for testing before the others, the simulation filled in the missing pieces.

To top off this modular construction process, the team came up with a new way to put all the sections together. Rather than being connected by cables, as with other torpedoes, the CAT’s communications and electrical connections at the ends of each section are joined by pins in what’s called a “blind mate” arrangement:  The operator doesn’t even need to see the pins to align and connect them.

As well as saving time, doing so much of the design via simulations trimmed costs. “This is one of the most inexpensive weapons, given what it is,” says Watson. “Compared to any of its predecessors, it’s probably a half to a third of the cost — because of the way it was designed, because of how easy it is to assemble.”

Once they built physical prototypes of key pieces of the vehicle, the group began tests in ARL’s water tunnel, one of the best facilities of its kind in the country. After live trials at sea, the new torpedo defense system began a test deployment on the supercarrier USS George H.W. Bush in March 2013. It has now been installed on four other ships.

Although the ARL has been one of the Navy’s go-to partners for research on undersea weapons systems since the mid-1940s, its story is not well known, says Burkhardt, in large part because much of its work is classified, and employees simply can’t talk about it.

That restriction also means that the engineers and scientists who worked on the CAT — 250 individuals, at the project’s peak — can’t do one of the major things university researchers are expected to do. “They’re not allowed to publish,” says Watson. “They give up that opportunity when they come here to work on these projects.”

“There’s a lot of pride with this group, and we love talking about it,” says Burkhardt. “It’s important for people to know that we are doing good things here.”

This story first appeared in the Spring 2017 issue of Research/Penn State magazine.