Dynamic Rollover of Gyroplanes during Landing—Cause and Prevention

Abstract

While new-generation gyroplanes are very stable during flight, the susceptibility to roll over briefly after touching down is still the issue due to incorrectly applied landing procedure. A tendency to dynamically roll over is also known from helicopters but rarely from airplanes. The main cause for rotary wing aircraft’s risk to rollover is the rotor force which is still relevant after touching down. The triangular wheel system of a gyroplane in combination with high centre of gravity is another factor for gyroplane’s rollover susceptibility during landing. Typical situations provoking a rollover are landings during severe crosswind or taxiing at too high ground speeds with a rotating rotor. Both situations are related to incorrect piloting techniques. In this paper, the forces acting on the gyroplane during landing were investigated to understand the physical principles. Analytical equations were evaluated using the data of a reference gyroplane in combination with a single-track model known from road vehicle dynamics. It appeared that a steering oversensitivity may occur if the pilot moves the stick forward too early after touching down. Non-linear simulations with a validated model of the reference gyroplane confirmed these analyses. Design parameter studies were conducted to analyse the impact on rollover susceptibility. Finally, this study confirmed that a rollover of a gyroplane during landing is most unlikely if the pilot applies the correct technique, which means pulling the control stick back properly after touching down.