2.2.2 Vehicle Physical Properties

Ranger NBV's overall dimensions are listed in Table 2-1.

Table 2-1 Overall vehicle dimensions

These dimensions are to the surface of the vehicle and do not include cover plates, fasteners, and fiber optic connectors. These items add about 1/4" to the front, top, and bottom of the vehicle, about 1/2" to the sides, and about 2" to the back.
The current mass properties are listed in Table 2-2. These values include the vehicle and two dexterous manipulators. The video and grapple manipulators have not yet been installed on the vehicle.

Table 2-2 Overall vehicle mass and buoyancy characteristics (NBV + 2 Dexterous Manipulators)

The approximate Ranger NBV manipulator mass values are shown in Table 2-3.

Table 2-3 Ranger NBV manipulator mass

When the video and dexterous manipulators are finally added to the vehicle, the total weight will be approximately 2000 lb. At this point, the manipulators will make up about 29% of the total vehicle mass.
These mass values were measured while the vehicle was on the deck, and do not represent the virtual mass added to the vehicle when it is in the water. When the vehicle is submerged, a large part of the propulsion module fills with water. When the vehicle is accelerated, this water, along with some of the water surrounding the vehicle, must also be accelerated. This virtual mass is difficult to calculate, and significantly alters the inertial properties of the vehicle.
A series of tests were performed with the vehicle both on the deck and under water in order to calculate the location of the vehicle center of mass and buoyancy. These are shown in Table 2-4. Notice that the location of these are the same since the vehicle is neutrally buoyant. The mass and buoyancy tests were conducted with the two dexterous manipulators in the stowed configuration. Changes in manipulator configuration can significantly modify these values.

Table 2-4 Locations of center of mass and buoyancy (in vehicle coordinates) (NBV + 2 dexterous manipulators in stowed configuration)