Improved Fuel Capacity Estimation Method

In this paper a new semi-analytical fuel tank capacity estimation method is developed for use in the conceptual design optimization of transport aircraft. It is based on a simplified spanwise thickness-to-chord ratio distribution model. Three variables are required to define this model, but reasonable simplifications can be made to use only one. The new method accounts for different geometries of the inboard and outboard integral tanks as well as the center wing tank. Rigorous statistical tests demonstrate the new method's superiority in both relative accuracy and consistency to all the other methods tested. The 95 % confidence interval of mean prediction error of the new method is -5.96 to +2.45% for conventional short- to medium-haul transport aircraft, which compares favorably with -13.37 to +6 % of a control method representing the current practice. Prediction error bandwidth observed in the sample is -6.7 to +5%. This improvement reduces the uncertainty about maximum fuel capacity and enables payload-range performance constraints to be more clearly defined.