An Evaluation of the Accuracy of Existing Empirical and Semi-Empirical Methods for Predicting the Wing Mass of Large Transport Aircraft

This paper investigates and evaluates the accuracy of various empirical and semi-empirical methods for predicting aircraft wing-structure mass. Eight methods were selected and analysed using data from large passenger-transport aircraft. The required technical data variables and specifications associated with these methods of wing-mass estimation were identified. When data were unavailable, sound engineering assumptions and judgments were applied as a last resort. The root mean square percentage error (RMSPE) was employed as the comparative indicator of accuracy to compute the average discrepancy between the predicted and actual wing-mass values. The resulting RMSPE values were 10% for the Kundu method, 13% for the Torenbeek II method, 15% for the Basgall method, and 17% for the Howe and LTH methods. According to the findings, the Kundu and Torenbeek II methods achieved the highest accuracy, with nonsignificant differences in their RMSPE values. Predicted wing mass was within [−12.5%, +11.7%] of the actual wing mass in approximately 62% of the study cases, which is adequate for most conceptual and preliminary aircraft-design purposes. Predictions were within [−22.3%, +20.6%] for about 25% of cases and within [−39.0%, +29.7%] for about 13% of cases. Furthermore, more complex methods did not enhance accuracy, as essential variables for these methods are often unavailable during the early design stage, rendering their inclusion less practical. Based on the collected and analysed data, a new updated formula for estimating aircraft wing mass is introduced. In comparison to the methods previously discussed, the new formula yields a superior overall RMSPE of 11%, significantly improving the accuracy of wing-mass estimation. Specifically, the results show an RMSPE of 6.5% for aircraft with a maximum takeoff mass exceeding 300,000 kg and 13% for those with a maximum takeoff mass below 300,000 kg. The refined method proves effective for wings with an aspect ratio of up to 10, offering reasonable accuracy during the conceptual design phase. However, some discrepancies still arise when this method is applied to unconventional aircraft.