In the season 5 episode "Timeless" of Star Trek Voyager, Harry Kim and Tom Paris concluded that a phase variance would cause a collapse of the Quantum Slipstream drive and thus cause fatal turbulence to star ship Voyager.

To remedy this problem, they decide the best course of action is to ride the Quantum slipstream ahead of Voyager in the Delta Flyer and send the calculated phase variance back to Voyager to make the journey safe. But what they didn't explain is how the Delta Flyer was able to ride the slipstream without problems itself.

Is there an explanation of why the Delta Flyer could calculate the phase variance first that star ship Voyager could not?