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This paper aims to introduce the take-off and landing performance analysis modules of the software library named Java toolchain of Programs for Aircraft Design (JPAD), dedicated to the aircraft preliminary design. An overview of JPAD is also presented.

The calculation of the take-off and landing distances has been implemented using a simulation-based approach. This expects to solve an appropriate set of ordinary differential equations, which describes the aircraft equations of motion during all the take-off and landing phases. Tests upon two aircraft models (ATR72 and B747-100B) have been performed to compare the obtained output with the performance data retrieved from the related flight manuals.

The tool developed has proven to be very reliable and versatile, as it performs the calculation of the required performance with almost no computational effort and with a good accuracy, providing a less than the 5 per cent difference with respect to the statistical trend and a difference from the flight manual or public brochure data around 10 per cent.

The use of a simulation-based approach to have a more accurate estimation of the ground performance with respect to classic semi-empirical equations. Although performing the simulation of the aircraft motion, the approach shown is very time-saving and can be easily implemented in an optimization cycle.

This work aims to deal with a comprehensive review of design methods for aircraft directional stability and vertical tail sizing. The focus on aircraft directional stability is due to the significant discrepancies that classical semi-empirical methods, as USAF DATCOM and ESDU, provide for some configurations because they are based on NACA wind tunnel (WT) tests about models not representative of an actual transport airplane.

The authors performed viscous numerical simulations to calculate the aerodynamic interference among aircraft parts on hundreds configurations of a generic regional turboprop aircraft, providing useful results that have been collected in a new vertical tail preliminary design method, named VeDSC.

The reviewed methods have been applied on a regional turboprop aircraft. The VeDSC method shows the closest agreement with numerical results. A WT test campaign involving more than 180 configurations has validated the numerical approach.

The investigation has covered both the linear and the non-linear range of the aerodynamic coefficients, including the mutual aerodynamic interference between the fuselage and the vertical stabilizer. Also, a preliminary investigation about rudder effectiveness, related to aircraft directional control, is presented.

In the final part of the paper, critical issues in vertical tail design are reviewed, highlighting the significance of a good estimation of aircraft directional stability and control derivatives.