Hi JimO

Tough question. The Sphere of Influence is at about 930,000 km and New Frontiers kicked off at about 16 km/s.

It's hyperbolic excess is pretty straight forward because it's on a parabolic trajectory - i.e. heliocentric speed is sqrt(2)*(Earth Orbital velocity) = 42.13 km/s. Which means a delta-V of (heliocentric) of 12.34 km/s... or thereabouts.

That's the hyperbolic excess. So the burnout speed at its parking orbit that's approx. 16.5 km/s.

The trip time is a little trickier. The SoI is at about 140 times its parking orbit.

So it'll pass 930,000 km after about 21 hours after burnout. Interestingly that's roughly 12.34 km/s x 21 hours, mostly because most of gravity's decceleration is close to Earth.

There's an ephemeris generator at JPL's SSDS web-site that'd be even more accurate, as I'm pretty sure you're already aware. Insider knowledge and all that. It gives distance with respect to Earth as an option.

As for other probes I always thought the previous fastest departing probe was Pioneer X, though the fastest in absolute terms would either be Helios at perihelion or Galileo's entry probe at entry into Jupiter.

Adam