The VMS motion base, the largest in the world, is a vital element in producing high-fidelity flight simulation. Housed in a ten-story building and driven by powerful motors, the motion base can sustain a movement for a relatively long period of time. For this reason, the VMS excels at reproducing conditions during critical phases of flight that are difficult to reproduce, such as landing and takeoff.
The motion base at the VMS features six degrees of freedom, meaning that the cab, with the pilot inside, can be driven in the six ways an aircraft moves. This includes the three translational degrees of freedom (vertical, lateral, and longitudinal) and the three rotational degrees of freedom (pitch, roll, and yaw).
The Motion Base from the top of the tower
The Motion Base from the bottom of the tower
VMS Motors
Providing the vertical degree of freedom is the vertical platform, which spans the 70-foot length of the building and supports the mechanisms for the remaining degrees of freedom. These photographs, looking down on the vertical platform and cab, show the vertical platform at its lowest and highest points.
Supporting the vertical platform are two columns that extend into 75-foot deep shafts. Guides on either end and on one side of the vertical platform keep it aligned.
Moving the 70-ton weight of the vertical platform and its load quickly is made possible by an equilibrator. This system pressurizes the two supporting columns with nitrogen, neutralizing the immense load. Eight 150-horsepower motors drive the columns, accelerating the vertical platform up to 22 feet/second/second, or almost 3/4 g.
Details of the VMS Motion Base
A small portion of the vertical platform is visible in the photograph below, together with the mechanisms for the remaining degrees of freedom. Providing lateral movement is the lateral carriage, which is capable of moving 40 feet toward the viewer. The lateral carriage is driven by four 40-horsepower electric motors.
Longitudinal movement is provided by the longitudinal carriage, with a range of 8 feet; in the photograph, it would move from left to right. The longitudinal carriage is driven by telescoping hydraulic actuators.
For flexibility in the delivery of cues, the cab can be mounted 90 degrees from the usual orientation. In this way, the larger 40-foot range can be used for longitudinal, instead of lateral, movements. For example, a study of the parachute used to slow the Space Shuttle Orbiter after landing used this orientation to provide maximum deceleration cues.
One of the VMS Caternaries
Like the longitudinal carriage, the three rotational degrees of freedom are driven hydraulically. The rotating center post provides yaw movements, and the pitch and roll actuators provide pitch and roll movements.
Two catenaries, which attach to the lateral carriage, protect the many electric, electronic, and hydraulic lines that connect the moving cab to the rest of the simulator. Hinges in the catenaries make them flexible, allowing them to move as the cab moves.
The motion base at the VMS delivers unexcelled motion cues for realistic flight simulation. It features six degrees of freedom and the largest motion range of any flight simulator in the world, providing invaluable realism in piloted simulation.