When does it burn fuel to carry fuel?
Granted, heavy metal transport aircraft - all the current reminders about tankering fuel or carrying an extra ton or so for the wife and kids results in comments of "it burns extra fuel to carry that fuel" - but when does that start to a significant extent?
Does it burn enough fuel to take into consideration when flying a Cessna 150 with full tanks on a one hour flight? Should that 150 go with 1½ hours fuel quantity (all things being equal with regard to known quantities/crap gauges etc).?
When does the fuel burn become significant? What size of aircraft?