APL's Underwater Launch Program provides valuable information to both the system designers and the Navy in understanding phenomena associated with the underwater launch of ballistic missiles from Trident submarines (SSBN) and from Trident submarines that are being converted to carry Tomahawk missiles. The Underwater Launch Program also has been responsible for designing and implementing the Launcher Integrated Diagnostics System (L-IDS), and developing a Sustainment Program to ensure the preservation of knowledge and information relevant to launching missiles underwater.

• The Underwater Launch Program investigates all phenomena affecting underwater launch. For the Trident II missile, underwater launch can be divided into five main phases, as shown in the following picture.

Significant progress has been made in understanding related issues by installing special crossflow instrumentation on the submarine for launches conducted during Demonstration and Shakedown (DASO) operations; this instrumentation has provided precise knowledge of the velocity of the water flow across the missile deck during those launches. This knowledge is critical to the validation of models which predict the Probability of Successful missile launching. This knowledge has aided the understanding of many phenomena affecting launch, such as how ventilation gas from the missile affects underwater flight stability, and the formation of the reentrant water jet. The figure below shows a depiction of the crossflow instrumentation system developed by the Underwater Launch Program to record and display real-time water speed across the SSBN missile deck during DASO missile launches.

DASO and other at-sea test launches (e.g., Commander Evaluation Test [CETs] or Follow-on CETs [FCETs]) provide opportunities to gather data to increase the understanding of underwater launch. The Laboratory works with other members of the underwater launch community (i.e., U.S. Navy Strategic Systems Programs [SSP] and SSP contractors) to recommend the depth and submarine speed for each DASO launch. The DASO launches are usually conducted at depths and ship speeds that normally will not be tested by the FCET program.

Launcher Integrated Diagnostics System

The Underwater Launch Program developed a Launcher Integrated Diagnostics System (L-IDS) that monitors components within the Trident II Launcher Subsystem and estimates their "health." One of the objectives of this project is to demonstrate the feasibility of implementing a condition-based maintenance system in a legacy system. An L-IDS prototype was defined and installed on the USS Louisiana for evaluation during deterrent patrol at sea. Based on results from the prototype testing and further project resource consideration, the system being tested at sea is limited to monitoring: relative umbilical positioning and movements of the Variable Energy Ejector (VEE) valve actuators.

As a result of initial investigations into Launcher components for L-IDS, the Underwater Launch Program is participating in some Integrated Product Teams (IPTs), which have been formed to investigate emergent problems. Among these are corrosion issues associated with the gas generator cooling chamber, and issues associated with the premature aging of Trident II gas generators.

Technology Sustainment

Since the beginning of the Navy’s Fleet Ballistic Missile Program, there has been a considerable investment in the technology required for the development and deployment of strategic underwater launched weapon systems. This investment has resulted in the most reliable, effective, and survivable strategic deterrent. Underwater launch of missiles is a key to the stealth of strategic systems and involves the interaction of a broad range of hardware and phenomena during several phases of flight from gas generator ignition to in-air powered flight.

The Underwater Launch Program is participating in a technology sustainment effort whose goal is to produce an historical collection of knowledge and a smart user interface which captures critical underwater launch technology and expertise that will guide future designers to the relevant test data, reports, validated models, and lessons learned. The historical collection will describe the underwater flight physics of submarine launched strategic missiles from gas generator ignition to initiation of powered flight. Appropriate new technology information also will be investigated and incorporated into the knowledge base. Establishment of a smart user interface to the knowledge base, the integrated launch models, and test facility evaluation will enable the cost-effective and timely development of future strategic underwater launch missile systems.