# Estimation of Stability Parameters for Wide Body Aircraft Using Computational Techniques
## 6 Conclusions  
In this paper, a detailed analysis of the stability and control parameters of Boeing 747-200 has been presented in light of results obtained from US DATCOM and XFLR software. The results obtained from computational techniques have also been verified with analytical correlations presented in the literature. The analysis of DATCOM gives meaningful results for the estimation of longitudinal stability and control with a complete set of derivatives from the knowledge of aircraft geometrical parameters for stability and control surfaces. The traditional wing-body-tail aircraft, including the control effectiveness for an array of high lift/control devices, are handled satisfactorily by DATCOM. Most of the stability and control coefficients for longitudinal and lateral modes were found to be reliable. However, some stability aspects are not very accurate. Directional stability and control require rudder derivative values, but there is no option for giving rudder input in DATCOM; hence, the directional stability values in the result are compromised. Furthermore, the derivatives obtained from DATCOM are used to calculate forces and moments; hence, the behavior of aircraft in the given flight regime can be analyzed satisfactorily by DATCOM. Hence, DATCOM is a useful tool since it has an inbuilt database of aircraft and airfoils as well. It is primarily a fixed-wing software. To get reliable results for UAVs in DATCOM, additional inputs and commands need to be added because it cannot register a body as an aircraft having conventional anatomy in the software by default. Moreover, twin tails are also not catered for in DATCOM. Hence, calculations on such configurations would yield inaccurate results. On the contrary, XFLR is a well-reputed stability analysis software that initiates the stability part by calculating the neutral point. All the forces and moments generated at given atmospheric conditions including Mach values are calculated in the form of derivatives. The results are produced in the form of graphs between different stability and control parameters and can be improved by merely tweaking the values. XFLR is an excellent option for viscous analysis. Its robustness and remarkable consistency give adequate results for complex flow problems. The results from XFLR can be verified by wind tunnel testing or vice versa. XFLR gives an added option of using a reflex airfoil instead of a conventional airfoil, which may be used for analysis of drones or rudderless aircraft. DATCOM is an old piece of software that needs to be upgraded as per the latest design and mission requirements. It also has a limitation of analysis regarding transonic Mach number regimes. The output file shows an NDM (no method exists) error that must be catered to while upgrading the application. Aircraft with twin tail configuration cannot be analyzed in DATCOM due to its inherent limitations; the same option may also be embedded. To obtain the directional control values, the option for giving rudder input could be included in the software. XFLR is a much better choice for the stability and aerodynamic performance determination of an aircraft; however, it also has certain flaws that must be considered and improved for future versions. For software that is extensively needed nowadays due to ever-increasing development in UAVs and unconventional air vehicle designs, XFLR must be designed with more sophisticated algorithms than the present one. XFLR can become slow for a large number of simulations, and it often crashes without giving a result. [PERSON], [PERSON] have proposed methodology of progressed research. The tasks involving data acquisition, software validation, formal analysis, investigation, draft preparation and editing were performed by them. The project was conceptualized by [PERSON]. Moreover, he was actively involved in the research work by his kind supervision. [PERSON] was involved in project administration and review as well as editing process. All authors have read and agreed to the published version of the manuscript.