This thesis examines how the composition of the U.S. fleet, with specific focus on small combatants, affects the ability of the United States Navy to undertake homeland defense missions and provides suggestions to improve its core competency. Currently, the U.S. Navy relies on a shrinking group of aging Oliver Hazard Perry class frigates to conduct counterpiracy, counter-narcotics, counter maritime insurgency, and maritime engagement missions. The large warships that make up the rest of the fleet are able to undertake these missions, but their cost and capabilities make them better suited for other operations. This thesis examines the proposed Littoral Combat Ship but argues that it is not the ideal ship: it is too expensive, too vulnerable, and undermanned, and it has a modular concept that is too underdeveloped for practical naval operations. Instead, this thesis proposes that the U.S. Navy would be better served by procuring a traditional frigate or corvette to accomplish the variety of missions that fall under the umbrella of homeland defense. Such a traditional small combatant would provide the U.S. Navy with a warship capable of conducting traditional fleet operations as well as operating at the lower end of the spectrum of operations

A unique high temperature modal test and model correlation/update program has been performed on the composite nozzle of the FASTRAC engine for the NASA X-34 Reusable Launch Vehicle. The program was required to provide an accurate high temperature model of the nozzle for incorporation into the engine system structural dynamics model for loads calculation; this model is significantly different from the ambient case due to the large decrease in composite stiffness properties due to heating. The high-temperature modal test was performed during a hot-fire test of the nozzle. Previously, a series of high fidelity modal tests and finite element model correlation of the nozzle in a free-free configuration had been performed. This model was then attached to a modal-test verified model of the engine hot-fire test stand and the ambient system mode shapes were identified. A reduced set of accelerometers was then attached to the nozzle, the engine fired full-duration, and the frequency peaks corresponding to the ambient nozzle modes individually isolated and tracked as they decreased during the test. To update the finite-element model of the nozzle to these frequency curves, the percentage differences of the anisotropic composite moduli due to temperature variation from ambient, which had been used in the initial modeling and which were obtained by small sample coupon testing, were multiplied by an iteratively determined constant factor. These new properties were used to create high-temperature nozzle models corresponding to 10 second engine operation increments and tied into the engine system model for loads determination.