How does G force at launch differ between spacecraft when it comes to efficiency between crewed and uncrewed space flight? Does less time in the atmosphere equate to a savings in fuel for an interplanetary launch? Could the common person or seasoned pilot safely withstand more then 3Gs if the burn time is also less?
Historically, Atlas and Titan boosters used in the Mercury and Gemini program subjected astronauts to as much as 8g on ascent for brief periods. Since the astronauts didn't need to do much during ascent, this wasn't a big problem; if they greyed out or even blacked out momentarily, the booster would continue obliviously on. These were practiced test pilots and combat pilots used to functioning through high-g maneuvers, but I believe any reasonably healthy civilian could survive a couple of short blackouts at 7g or 8g.
Later boosters purpose-built for crewed flights traded off a small amount of delta-v capability for crew comfort; Saturn-Apollo topped out at 4g and Shuttle at 3g.
The Titan II Gemini launch vehicle expended about 8950 m/s of delta-v to reach orbit; the Saturn V expended about 9200 m/s, so dropping from 8g peaks to 4g peaks incurred slightly less than a 3% ∆v efficiency penalty.
Due to the nonlinearity of the rocket equation, the difference in fuel mass is less than 3% (and depends greatly on the particular design of the launcher). For a two-stage-to-orbit launcher, all other things being equal, the fuel mass needed for an 8g peak ascent is probably about 1% more than needed for a 4g peak ascent.