AƩrospatiale/BAC Concorde supersonic passenger airliner for when you need to get out of the country in a hurry.
Carries up to 32 of your richer Kerbals past Mach 2 for a comfortable cruise of about… 30 minutes.
On normal power the engines are useless for anything but landing, although you can take off with them and cruise subsonic if you’re flying over populated areas. Otherwise afterburner all the time, it’s the Kerbal way. Accelerate past Mach 2 at around 7k altitude then climb to 10k and cruise at half throttle.
High G Maneuvers above Mach 2 are not recommended. Handles gentle enough at slow speeds and is pretty easy to land.