Modern flight configurations are trending towards slender wings of larger wingspans and lower structural weight. New designs are driven by performance requirements (reduction of fuel consumption, or flight at the boundary of the atmosphere, for example) as well as by innovations in softer materials (such as polymers used in rapid prototyping). These result in configurations that are lighter but more flexible than before. For very flexible configurations, the industry-standard computational formulations based on linear structural models are no longer adequate. Consequently, novel, nonlinear structural models are being developed for the aeroelastic analysis of structures that experience large deformations. Due to their complexity, nonlinear structural models tend to be either limited to simple geometries (beams, for example) or highly detailed and computationally expensive (nonlinear finite-element models). The study presents the derivation and application of the Modal Rotation Method (MRM), a nonlinear framework for the static and flutter analysis of highly flexible, slender wing-like strictures accounting for large deformations. It uses a linear modal database which makes it easy to use, and computationally efficient. The framework is used both for the analysis of slender structures under prescribed flight conditions and as a part of a nonlinear strain-based shape sensing algorithm. The talk will focus on the MRM formulation and its validation, both numerically and experimentally, with several test cases including the Pazy wing aeroelastic benchmark for large deformations, and will then briefly present the MRM strain-based a shape sensing application.