The Woodruff School

SUMMARY

Helicopters are a vital asset to both civilian and military sea operations. Navy and Marine missions are conducted on a continuous basis to support sea operations and occur during the day, at night, and in all types of weather conditions. Due to aircraft endurance limits, helicopter ship landings are sometimes time critical, forcing landings in non-ideal conditions. Landing a helicopter safely on a ship at sea is a difficult task for military helicopter pilots as it is difficult to accurately estimate the orientation of the landing surface as the ship heaves, pitches, and rolls. Compounded with the limit landing area, small ships are even more susceptible to large movements in inclement weather. Aircraft equipped with robotic landing gear have the potential to rapidly and safely land on highly sloped terrain that is much greater than current limits of approximately 10 degrees. Furthermore, robotic landing gear will enable these aircrafts to land onto small, moving landing areas that is not possible with current rotorcraft. This new active landing gear concept could be used by both piloted and autonomous aircraft, and could expand operational capability for future rotorcraft by greatly expanding available landing areas and greatly increasing the speed of landing while reducing pilot workload. A helicopter-ship landing event simulation was developed to evaluate the viability of robotic landing gear for use on rotorcraft for shipboard landing. It is composed of a dynamic ship model, rotorcraft multibody dynamic model, pilot model, rotor model, contact force model, and landing gear control system. The rotorcraft multibody dynamic model were derived for a rotorcraft with a quadruped, 2-legged robotic landing gear (RLG). The Virtual Model Controller (VMC) was derived and adapted to this RLG configuration, which aims to keep the fuselage level after the rotorcraft lands on the ship deck. Trade studies and Monte Carlo simulations were conducted with the helicopter-ship landing event simulation to evaluate the RLG performance during shipboard landing in harsh landing conditions. The use of a grasping, or deck-locking, mechanism on the ends of the RLG to keep the RLG in contact with the ship deck was also investigated.

SUBJECT:	Ph.D. Dissertation Defense

BY:	Dooroo Kim

TIME:	Friday, March 1, 2024, 1:00 p.m.

PLACE:	Teams Meeting, virtual

TITLE:	Shipboard Landing of Rotorcraft with Robotic Landing Gear

COMMITTEE:	Dr. Mark Costello, Chair (ME/AE) Dr. Aldo Ferri (ME) Dr. Anirban Mazumdar (ME) Dr. Jonathan Rogers (ME/AE) Dr. Caudio Di Leo (AE)

SUMMARY Helicopters are a vital asset to both civilian and military sea operations. Navy and Marine missions are conducted on a continuous basis to support sea operations and occur during the day, at night, and in all types of weather conditions. Due to aircraft endurance limits, helicopter ship landings are sometimes time critical, forcing landings in non-ideal conditions. Landing a helicopter safely on a ship at sea is a difficult task for military helicopter pilots as it is difficult to accurately estimate the orientation of the landing surface as the ship heaves, pitches, and rolls. Compounded with the limit landing area, small ships are even more susceptible to large movements in inclement weather. Aircraft equipped with robotic landing gear have the potential to rapidly and safely land on highly sloped terrain that is much greater than current limits of approximately 10 degrees. Furthermore, robotic landing gear will enable these aircrafts to land onto small, moving landing areas that is not possible with current rotorcraft. This new active landing gear concept could be used by both piloted and autonomous aircraft, and could expand operational capability for future rotorcraft by greatly expanding available landing areas and greatly increasing the speed of landing while reducing pilot workload. A helicopter-ship landing event simulation was developed to evaluate the viability of robotic landing gear for use on rotorcraft for shipboard landing. It is composed of a dynamic ship model, rotorcraft multibody dynamic model, pilot model, rotor model, contact force model, and landing gear control system. The rotorcraft multibody dynamic model were derived for a rotorcraft with a quadruped, 2-legged robotic landing gear (RLG). The Virtual Model Controller (VMC) was derived and adapted to this RLG configuration, which aims to keep the fuselage level after the rotorcraft lands on the ship deck. Trade studies and Monte Carlo simulations were conducted with the helicopter-ship landing event simulation to evaluate the RLG performance during shipboard landing in harsh landing conditions. The use of a grasping, or deck-locking, mechanism on the ends of the RLG to keep the RLG in contact with the ship deck was also investigated.