From this graph, Fujita then released the following descriptions for the F-Scale http://www.spc.noaa.gov/faq/tornado/f-scale.html. Over the years, the F-Scale has revealed the following weaknesses: 1  It is subjective based solely on the. 2  caused by a tornado.
9 Answers. The empty weight is the weight of the airplane including anything that is permanently attached to it and includes any un-drainable fluids. There is a maximum gross weight for takeoff and on larger aircraft there may be a maximum landing weight. The useful load is the difference between the maximum gross weight and the empty weight. To the empty weight, you have to add the fuel, oil, any other fluids, pilot and passengers, and baggage.
What makes airplanes fly are the four forces of flight, thrust, provided by the engines, propelling the airplane forward, lift pulling the airplane up, drag pulling the airplane back, and weight, or gravity pulling the airplane down. How much an airplane weighs, depends on the plane.