The closest I'm aware of for active research is SpinLaunch: https://www.nextbigfuture.com/2018/02/spinlaunch-is-using-large-centrifuges-to-accelerate-to-payload

The closest I'm aware of for active research is SpinLaunch: https://www.nextbigfuture.com/2018/02/spinlaunch-is-using-large-centrifuges-to-accelerate-to-payloads-into-space-target-500000-per-launch.html https://www.nextbigfuture.com/2018/02/spinlaunch-is-using-la... ...but isn't using rails. Rails are kind of a pain anyway as they have a habit of eroding.