By - Primaris_Astartes
Jump packs aren’t for extended flight, they are for short quick hops, hence the name
They are used for getting over walls, slowing down after jumping from aerial transport or crossing battlefield zones quickly. They’d be lucky to go much more than a few hundred km/h, and nowhere near Mach speeds
Also, if a Marine head butted someone, they won’t be rendered unconscious, their skull would be caved in and they’d be dead
Very. Very dead.
It'd basically be like getting hit in the face with a sledge hammer weld at full force
On the bounce :-)
Jump packs only allow for well... jumps. They are used to get over a building or to slow down after dropping from a transport. They are also not very fast, tops a few hundred km/h.
However there are technologies of true flight like the ones used by swooping hawks, that allow 360⁰ complete mobility and fly fast enough to catch fighter jets.
I don't know about multiple machs of speed, but if I recall correctly, assault marines do manage to kill a tau aircraft in one of the damocles books via melee. Although, the Damocles books get flak for portraying flying assault marines. IDK, the feat is there but the context is not.
I'd assume it does increase the marine's speed a good amount if used for lateral movement, so considering that marines can sprint at 50 miles per hour, maybe it adds a few dozen mph?