Lateral-directional trim for air and ground minimum control speeds evaluation in conceptual design

This paper presents the development of a comprehensive methodology for accurately estimating minimum control speeds both in the air (VMCA) and on the ground (VMCG), addressing a gap in conceptual design methodologies. These speeds are critical for appropriately sizing the rudder and vertical tailplane and ensuring controllability during one-engine-inoperative scenarios. The proposed approach integrates a nonlinear lateral-directional trim analysis and a time-domain simulation of ground manoeuvres, accounting for landing gear-runway interaction effects. The methodology facilitates a precise and rapid estimation of VMCA and VMCG while adhering to physical and regulatory constraints, making it suitable for early design iterations. It serves as a key procedure for optimising the design of aircraft with Short Take Off and Landing capabilities, which may exhibit controllability issues at near-stall speeds. A comparison of the data with those documented in the C-130J Performance Data Manual and the ATR 72–500 Flight Crew Operating Manual exhibits a close match across a wide range of operational conditions.