I got one of my SST's up to Mach 4.335!

Now I know that in terms of Kerbal that's not that fast so I'm gonna give you some context. This puppy carries roughly the same amount of people as the Concorde did (Though with much more leg room), and can go more then 2 times the Concorde's top speed of Mach 2. Yeah. This is an airliner that travels 1,019mph (1,640kmh) faster then a SR-71 Blackbird.

Here it is flying through some mountains as it climbs

and on the runway