Alpha Sea Trials
Navy officials and shipyard workers strained to catch a glimpse of the attack submarine VIRGINIA through the mid-day fog. On that Friday afternoon, July 30’h 2004, VIRGINIA was returning from her first time at sea to the Electric Boat shipyard in Groton, Connecticut where she was constructed. As VIRGINIA came into view, steaming up the Thames River, a straw broom was seen strapped to a mast, evoking the tradition of World War II submarines returning from successful war patrols. “The broom signifies exactly what it should -a clean sweep,” said Admiral Frank L. “Skip” Bowman, Director, Naval Nuclear Propulsion. Every test conducted on VIRGINIA ‘s first sea trial had been a success.
VIRGINIA’s Alpha Trials were the first in a series of Builder’s Trials that every nuclear powered submarine undergoes before entering the Fleet. Alpha Sea Trials brought the ship to life. It consisted of maneuverability testing, propulsion testing, an initial tightness dive, a dive to maximum authorized depth and an Emergency Main Ballast Tank (EMBT) blow. “She performed as expected and more,” according to Captain David Kem, CO of VIRGINIA. “Everything went great.”
VIRGINIA’s initial dive was conducted as a controlled and closely monitored evolution. It started by submerging to periscope depth. After obtaining a diving trim at speed, VIRGINIA continued going deeper step-by-step. The initial trim dive was concluded with a successful emergency main ballast tank (EMBT) blow from 200 feet, proving that the EMBT blow system was operationally ready to support deeper diving evolutions. As the lead ship of its class, VIRGINIA also conducted a dive to test depth-the maximum permissible depth-on this trial. Later ships will make the first dive to test depth during the second or Bravo Sea Trials. On the dive to test depth, all major hull, machinery, and electrical equipment were checked at incrementally deeper depths. The Crew also monitored for any evidence of leakage from hull penetrating systems. Overall, VIRGINIA performed three emergency blows and dove to test depth three times. She also conducted maneuvers to validate hydrodynamic modeling and observe that responses of the hull and control surfaces were as expected.
Propulsion plant testing went flawlessly. The testing included runs at maximum speed surfaced and submerged. VIRGINIA’s top speed met expectations. In addition, a test from all ahead flank speed ahead to back emergency, called a crash back, proved that the propulsion plant could handle rapid changes and slow the ship in an emergency as prescribed. Drills were also used to test the response of the crew and the propulsion plant in abnormal situations. The level of automation in VIRGINIA’s propulsion plant has made it more user-friendly and has even reduced the number of crewmen required to operate and maintain it. The new plant design incorporates modem electronics, micro-processing, and digital analysis and displays to a greater extent than ever before. Furthermore, the new design propulsion plant is quieter than that of any previous submarine class. VIRGINIA ‘s reactor fuel will last the lifetime of the ship, which will reduce lifecycle cost and increase the operational availability of the ship.
For Alpha Sea Trials, there were 206 personnel on board or the equivalent of I 3/4 crews on a submarine designed with 119 berths. Temporary test equipment and supporting instrumentation further limited available space, which is always at a premium on submarines. Nevertheless, the crew and people from the shipyards, navy labs, and vendors adapted to these conditions and smoothly worked together around the clock for three days in order to accomplish all tests. This large number of people on board imposed a test of its own on eating and sleeping facilities, but VIRGINIA was capable, thanks to her new design. A torpedo room which can be reconfigured to accommodate special operations forces greatly aided berthing of non-crew members. The new food service arrangement, which facilitates serving and eliminates forward and aft traffic through the crew’s mess, assisted the cooks in feeding all that were on board.
Overall, successful completion of required tests validated propulsion, ship handling, and safety characteristics, setting the stage for subsequent trials. The ship demonstrated superior dynamic stability and ship handling characteristics, and the fly-by-wire ship control system not only met, but exceeded expectations. There were fifty non-propulsion deficiencies-all minor and more representative of a ship of a mature class of submarines than the lead ship of a new class. The minor nature of these problems was evidenced by our ability to turn VIRGINIA around to be ready for the second sea trial in just three days.
Preparation Was Key
Major credit for the triumph of this first underway operation must be attributed to the high level of crew training, dockside testing, and certification that was concluded before VIRGINIA ever proceeded to sea. All the advance preparations significantly reduced the risks of problems at sea and greatly improved the chances of achieving successful test results. As with all new construction submarines, the steps to underway operations for VIRGINIA included Phase I Crew Certification, Salvage Inspection, Habitability Inspection, Dock Trials, Phase TI Crew Certification, and Fast Cruise. In addition, VIRGINIA already had successfully completed intensive equipment and systems testing in order to be certified as ready for underway operations. As a result, VIRGINIA had been more fully tested before getting underway than any previous class of submarine.
VIRGINIA ‘s crew had likewise been exhaustively preparing themselves. For several years, they have supported construction of their ship and recently were very busy as the time came for them to accept turnover of ship systems and spaces from the shipbuilder. In preparation for at-sea operations, the crew also spent numerous hours learning new equipment and systems, including time in trainers and classrooms. They also practiced equipment operation, ship evolution, and casualty drills to satisfy crew certification testing. At sea, I was extremely impressed by their proficiency especially since this was their first time underway in a new class of ship with a plethora of new systems and procedures to follow.
A high level of early testing was performed on VIRGINIA’ s Non-Propulsion Electronics System (NPES), and provided results that gave confidence that the risk of using new commercial-off-the-shelf (COTS) technologies and standards was minimized. In other words, VIRGINIA NPES had gone to sea through computer simulation many, many times, before the ship headed down the channel. The NPES is a system of systems consisting of 23 electronics systems, such as Command and Control, Sonar, and Navigation, integrated into a ship wide network that hosts an impressive 20 million lines of computer code. It was designed to facilitate rapid incorporation of new computer technology or mission capability to keep the submarine technologically current. To meet these goals, the NPES design is almost completely based on COTS electronic systems and the concepts and processes of Open Architecture (OA). OA has simplified many of VIRGINIA’s systems and has reduced the cost and time to develop them.
The NPES with its largely COTS-based hardware is not inherently shock resistant. Therefore, it is assembled into a specially designed Command and Control System Module (CCSM), a modularized, shock-isolated, deck structure package. Then the CCSM is tested as a complete system. An off-hull test facility called COATS (Command and Control System Module Off-hull Assembly and Test Site) was built in Groton, CT, for complete NPES system assembly, checkout and integration testing.
At the COATS facility, VIRGINIA ‘s CCSM completed integration testing a full two years prior to sea trials versus the typical nine to twelve months. This process reduced costs and helped to ensure that once the CCSM systems were aboard the ship they functioned reliably. This approach drastically reduced the risk of testing impacting VIRGINIA’ s delivery schedule by allowing time for fixes or refinements as needed. We also greatly reduced the waterborne testing effort and eliminated an enormous amount of administrative work. Leaning alongside the developers at COATS, VIRGINIA Sailors gained important understanding of the inter connectivity of systems that they ably demonstrated at sea.
Upon completion of testing, Commander, Operational Test and Evaluation Force (COMOPTEVFOR) performed an operational evaluation (OT-JIB) of NPES. During this event, Fleet Sailors participated in 571 hours of system operation under test conditions that increased their familiarity with the new equipment and procedures. VlRGINIA passed this rigorous test on the first try. OT-IIB validated NPES and identified deficiencies while plenty of time remained to make corrections and changes without delaying the construction and sea trials schedule. The testing results of Alpha Sea Trial showed how closely the land-based testing predicted actual performance.
Pre-underway testing of VIRGINIA ‘s torpedo system was passed with 12 flawless firings of torpedo test shapes over two days in March. The tests checked every aspect of torpedo handling and firing systems from loading into the ship, moving and stowing in the torpedo room, loading into torpedo tubes, and firing. Three shapes were fired from each of four tubes. The dozen shots and dozen successes have laid the foundation for repeating the successful test results at sea.
Certification for Sea
Before PCU VIRGINIA cast off the last mooring line and headed for sea trials, she was certified under the highly structured Submarine Safety (SUBSAFE) Program. Before VIRGINIA could be certified for sea by SUBSAFE requirements, she was subjected to many tests of systems built with certified material using approved assembly procedures that were thoroughly documented. Objective quality evidence (OQE) of material control and work discipline was reviewed to assure compliance with SUBSAFE requirements. Then documentation and information required for NA VSEA Headquarters Certification was reviewed and approved by SEA 07T, the warranted Technical Authority, and SEA 07Q, the SUBSAFE Office. Subsequently, as the Program Manager, I had the responsibility of reviewing all material records and waivers to assess that VIRGINIA met the requirements for diving safely. After approving the package, I presented it to RDML John Butler, PEO SUB, the Certifying Official.
SUBSAFE lessons came to mind when a digital Fly-By-Wire Ship Control System (FBW SCS) was specified for VIRGINIA. With Fly-By-Wire (FBW), steering and depth are controlled electronically by computer without mechanical inputs, in both normal and emergency modes. This new method of ship control with no hydraulic or mechanical linkage between the ship control station and the submarine’s control surfaces required a new certification process. Therefore the Requirements Manual for Submarine Fly-By-Wire Ship Control Systems was developed under the leadership of Commander Gary Dunlap in my office and instituted to provide a certification program parallel to the SUBSAFE Program. This system uses the same kinds of requirements and disciplined practices as SUBSAFE, but applies them specifically to ensure fail-safe operation of the FBW SCS. The program requirements focus on software and electronics that process ship control related signals. As with SUBSAFE, FBW has critical component material identification and control requirements for elements contained within the FBW boundary.
Much is radically new about the Ship Control Station (SCS), which is the main interface between the crew and 11 ship control-related subsystems. The SCS has a graphical user interface with four miniature operational stations (mini-stations), two joysticks, and a Mode Select Panel. Each mini-station provides complete ship control capability and consists of a large flat panel display screen and a small one. Each display accepts touch inputs. There are two SCS operator stations manned by the Pilot and Co-pilot. In automatic mode, the Pilot or Co-pilot orders course and depth on the touch-sensitive screen for steering and diving. In this mode, the system computes and moves the stern planes, bow planes, and rudder, to attain ordered course and depth. Because VIRGINIA has two sets of stem planes, the mini-station shows if inner and outer stem planes angles match. The inner and outer stem planes are about equally effective, so if one set jams or fails, the other set moves to counteract the effect. When entering a steering or diving order, there is a way to accelerate or limit the automatic performance. Three screen buttons allow selection of normal, limited, or maximal response to cause the system to move the planes or rudder within preset limits with the desired expediency. One feature is straight from the Star ship Enterprise with the computer that spoke with a human voice: A planes casualty in automatic produces a human voice prompting action to take manual control.
In normal manual mode, operators use either of two joysticks for manual control of the rudder, planes and the hovering and depth control seawater flow control valve. The SCS senses the position of the operator’s joystick via fiber optic cable and digitally translates this movement into corresponding commands to hydraulics to move the control surfaces. While modem aircraft use this type of link, it is a first for US submarines. Operators previously used an aircraft-style stick and yoke, operating servo-control valves to change the flow of hydraulic oil to the control surfaces.
VIRGINIA Class has no mechanical-hydraulic mode of operation for backup as in the past. The emergency mode for loss of power is the Minimal Electronics Mode (MEM). If AC power is Jost, MEM can use battery power for about 30 minutes to command positioning of aft control surfaces independent of computer control. In addition, the SCS system has fault-tolerant and performance-monitoring features to provide reliability.
The SCS Fault-Tolerant Processing System (FTPS) allows the ship control system to operate following failures of ship control electronics, sensors, or actuation systems. FTPS has four redundant processing units that control and monitor all operator interfaces, control outputs, and sensor inputs. All four units are synchronized for real-time data sharing and data comparison. Their performance-monitoring circuitry provides detection of processing and communications errors and auto recovery. Recovery from ship control failures is accomplished by automatic switching from a faulty component to a redundant copy that has not failed. Performance monitoring software development was a major challenge for VIRGINIA Class because of the complexity of dealing with several hundred signals, each connected with various forms of quad, dual, or simplex redundancy in order to build in the necessary reliability.
Why deal with a system that is so complex and different and has lots of new requirements? There are a number of advantages that accrue to VIRGINIA by using fly-by-wire technology. Fly-By-Wire provides a self-stabilizing capability. The SCS receives depth, heading, pitch and roll data to cause it to react with the right amount of limited control input to maintain stability. The electronic control system enables intelligent operator assistance in hazardous situations and assists recovery from a casualty. For example, there is an emergency-deep algorithm and corresponding screen “button”. If “emergency deep” is ordered, the Pilot just touches the Emergency Deep button on screen, and then confirms the order. When he confirms, the system takes all the initial actions to go deep. This reduces the demand on the Pilot and is part of the reason the size of the ship control party is reduced on VIRGINIA. Fly-By-Wire decreases the space and weight requirements of SCS too; always a welcome feature on a submarine. Fly-By-Wire also offers a reduction in cost, especially life cycle cost as it reduces required maintenance, crew size, and training.
Underway, the performance of the SCS in auto was very smooth. The operators love it. To go to periscope depth, the Pilot merely brings up the keypad on the depth screen and touches and enters the depth order akin to using a calculator. The system achieved more stability than human operators typically do. This was really apparent during periscope depth operations when depth control is the most challenging. Even on the edge of Hurricane Alex, early in Bravo Trials, depth control in automatic was precise and the ship never broached. VIRGINIA’s hovering system is another means of automated depth control when near zero speed. Hovering will aid launching or recovering of SEALs. While maintaining depth by hovering for lockout trunk testing, the need arose to expose the deck because of fouling of a deck hatch. A specific depth was put into hovering that would broach the ship. While planes would have been ineffective under these conditions, hovering took the ship to that shallow depth and held it.
To ensure operator proficiency is maintained for the manual mode of operation a new trainer has been placed in operation at the submarine school in Groton, Connecticut.
All these trials lead up to authorization for “unrestricted operation”.
VIRGINIA ‘s second sea trial integrated the standard Bravo and Charlie Sea Trials. The second set of trials concentrated on a noise survey and in-depth testing of all ship control, trim, and ballasting systems, and the weapons and combat systems. These trials lasted three weeks. The majority of time was spent on acoustic testing in the Caribbean for the shipbuilder to characterize the ship’s acoustic signature. Later the Navy will conduct more extensive signature definition trials. With initial sea trials complete, VIRGINIA arrived at Norfolk, VA, having already traveled some 6000 miles. At this writing the ship is in dry dock for about two weeks at Norfolk Naval Shipyard, followed by three to four weeks waterborne for correction of trials deficiencies and final preparations. The Naval Board of Inspection and Survey (INSURV), or Acceptance Trials, is combined with the final contract trials. These trials will be conducted for about a week by the INSURV Board as an independent verification of the ship’s material readiness condition. Subsequently, VIRGINIA will return to Norfolk to prepare for delivery to the Navy and for commissioning on the 23’d of October 2004. This schedule is in keeping with the Acquisition Program Baseline approved over 11 years ago that set down delivery of VIRGINIA by this year-a very significant accomplishment!
The success of VIRGINIA sea trials is near-term fulfillment of all the promise that VIRGINIA holds. To my knowledge, no lead ship has undergone trials with so few problems. The superb results are gratifying, but were made highly probable by the measures taken during design, construction, and testing to reduce the risk of problems once VIRGINIA got underway. Yet there is only so much that can be proven from modeling, simulations, and ashore and dockside testing. The full-scale ship tests in the unforgiving ocean environment have now confirmed that the designers got it right. The splendid performance of men and machinery underway should instill even greater confidence in the Program and in our shipbuilders.
VIRGINIA proved by these results that she is quiet, fast, maneuverable, and ready. She is fulfilling in every way the promise inherent in her design to be a key instrument in the Navy’s transformation. With superlative results from Builder’s Trials, we look forward to successful accomplishment of the remaining steps to ship delivery when VIRGINIA officially joins the Navy. The multi-mission flexibility that VIRGINIA Class submarines offer to fleet and joint forces, combined with their new and expanded war fighting capabilities, places VIRGINIA on the cutting edge of future Submarine Force operations.