  We study some properties of the tangent bundles with metrics of general
natural lifted type. We consider a Riemannian manifold $(M,g)$ and we find the
conditions under which the Riemannian manifold $(TM,G)$, where $TM$ is the
tangent bundle of $M$ and $G$ is the general natural lifted metric of $g$, has
constant sectional curvature.
