747-400 take off from Fairmont State Airfield, KFMZ. No passengers or cargo, two 115 pound women pilots, an 18 mph headwind, just enough fuel to get over to Offutt AFB. Fairmont was originally home to B-24s and B-29s. 4315 ft. runway. I tried this in both FSX and X-Plane with the same results. When I was young, I used to sit at the end of Love Field runway, and watch 747-100s loaded, clear the fence by about 15 feet. That was an 8800 ft. runway.