  Cosmological models of Bianchi type V and I containing a perfect fluid with a
linear equation of state plus cosmological constant are investigated using a
tetrad approach where our variables are the Riemann tensor, the Ricci rotation
coefficients and a subset of the tetrad vector components. This set, in the
following called S, describes a spacetime when its elements are constrained by
certain integrability conditions and due to a theorem by Cartan this set gives
a complete local description of the spacetime. The system obtained by imposing
the integrability conditions and Einstein's equations can be reduced to an
integrable system of five coupled first order ordinary differential equations.
The general solution is tilted and describes a fluid with expansion, shear and
vorticity. With the help of standard bases for Bianchi V and I the full line
element is found in terms of the elements in S. We then construct the solutions
to the linearized equations around the open Friedmann model. The full system is
also studied numerically and the perturbative solutions agree well with the
numerical ones in the appropriate domains. We also give some examples of
numerical solutions in the non-perturbative regime.

General Relativity and Quantum Cosmology