I was just looking though Flightaware, and I saw that Polar Air have a non stop LAX-NRT service, operated by 744Fs. I thought that 744Fs, did not have the legs for LAX-NRT, so how is Polar able to this?
Less than full plane? With equal payload, a freighter will fly nearly as far as far as a passenger plane will (freighters tend to have slightly higher OEWs) but the difference in practice is that freighters usually get loaded down, since freight doesn't mind making a stop.
Why do Aerospace Engineering students have to turn things in on time?
LAX-NRT is only 4800 nm (great circle). You can do that with a 747-400F comfortably if you go out at MTOW and reduce payload by about 30,000 lbs from maximum (about an 11% hit). At that part of the payload/range curve you're MTOW limited.
At maximum payload, a 747-400F will go about 4300 nm.
Polar also does HKG-CVG which is about 7700 NM, granted the route has tailwinds. They're usually limited to about 65% payload (about 75 tons of freight max). Polar carries a lot of DHL package freight which can often be bulky but not too heavy, so the payload restrictions aren't a route killer.
I guess you don't remember that the airlines flew the Classic on that route non-stop? Actually, the empty weight of a freighter is less than a passenger plane since you don't have galleys, seats, entertainment, meals etc. Yes, you do have a strengthened floor and cargo handling system. Often, the actual takeoff weight of a freighter is higher than a passenger plane with all seats occupied.