How fast is Mach 7?
- 7,608.5958 ft/sec
- 1.44102193 miles/sec
- 2.319099997 km/s
- 2.37168138e-4 parsecs/century and stuff
is approximately 1% of the speed of the solar system in its galactic orbit around the Milky Way (approx. 143 miles/sec || 230 km/s), or 1/130,000 the speed of light, or 2.184285873e-6 percent of the distance we travel the orbit around the Milky Way in the Galactic Year/ second, or 1.00830435% of the speed of the Galactic Year ride, zoom zoom! That last figure has a degree of tolerance at more than ± 12%.
You need to be going Mach 1798 to achieve escape velocity from the Local Group (370 miles/second) on its way to the Great Attractor, so you could build something that can go 1,326,934.121 mph faster than a rail gun projectile to do that, maybe.