  We address a free boundary model for the compressible Euler equations where
the free boundary, which is elastic, evolves according to a weakly damped
fourth order hyperbolic equation forced by the fluid pressure. This system
captures the interaction of an inviscid fluid with an elastic plate. We
establish a priori estimates on local-in-time solutions in low regularity
Sobolev spaces, namely with velocity and density initial data v0,R0 in H3. The
main new device is a variable coefficients space tangential-time differential
operator of order 1 with non-homogeneous boundary conditions, which captures
the hyperbolic nature of the compressible Euler equations as well as the
coupling with the structural dynamics.
