In this paper we consider a fluid-structure interaction problem given by the steady Navier Stokes equations coupled with linear elasticity taken from [Lasiecka, Szulc, and Zochoswki, Nonl. Anal.: Real World Appl., 44, 2018 ]. An elastic body surrounded by a liquid in a rectangular domain is deformed by the flow which can be controlled by the Dirichlet boundary condition at the inlet. On the walls along the channel homogeneous Dirichlet boundary conditions and on the outflow boundary do-nothing conditions are prescribed. We recall existence results for the nonlinear system from that reference and analyze the control to state mapping generalizing the results of [Wollner and Wick, J. Math. Fluid Mech., 21, 2019 ] to the setting of the nonlinear Navier-Stokes equation for the fluid and the situation of mixed boundary conditions in a domain with corners. Contents 1. Introduction 2. The domain 2.1. The flow map and some transformation rules 2.2. Transformation of integrals 2.3. Transformation of the Navier-Stokes equation 3. Existence of solutions for the considered systems 3.1. The Navier-Stokes system 3.2. The elasticity system and the traction force 3.3. The fluid-structure interation system 4. The linearized equations 4.1. Linearized state equation: Coefficients equal to one 4.2. The linearized state equation 4.3. Lower regularity 4.4. Higher regularity 4.5. Limit behaviour 5. Differentiability Appendix A. Transformation of the Navier-Stokes equation Appendix B. Transformation of the linearized Navier-Stokes equation Appendix C. Some properties References