Some Questions

[Timerover51]

In the YIARN CAARDEE Vehicle Catalogue, there is continual references to a standard of weight and volume referred to as "vl". Nowhere is "vl" defined in terms of volume. What exactly is it?

There is also the comment that

Because water occupies about one cubic meter per metric ton, the displacement tonnage also defines the volume of the ship below the waterline.

One metric ton of fresh distilled water at a specified temperature equals one cubic meter of volume. There is no "about" to it. A cubic meter of salt water weighs slightly more than one metric ton, approximately 1.026 metric tons. One long ton, 2240 pounds, of salt water occupies 35 cubic feet, which gives the submerged volume of the ship, and also the weight of the ship in long tons. When specifying the displacement of a ship, you need to be careful to specify whether you are using a metric ton or a long ton. The difference in weight between fresh water and salt water means that a ship will ride deeper in fresh water than salt water, as fresh water is less buoyant.

Lastly, there is the statement that

a vehicle's loaded weight in kilograms is equal to its size in vls.

The 1943 Half-track CARRIAGE, MOTOR, MULTIPLE GUN, M16 with a quad powered .50 caliber machine gun mount had a gross weight of 19,800 pounds. The 1953 DUKW had a gross weight of 20,055 pounds, so very close to the same weight. The Half-track, when boxed for transport by cargo ship, had a volume of 1188 cubic feet. The volume for the DUKW, uncrated, was 2260 cubic feet. In 1943, the listed gross weight for the DUKW was 19,800 pounds. There is no hard and fast rule for volume verses weight in ground vehicles, and for buses, the cubic footage for volume is even higher than the DUKW. Conversely, the M4A4 Sherman tank had a combat weight of 71,900 pounds, and a shipping cubic volume of 1,529 cubic feet.

 

[steventirey1985]

Somewhere in the T20 core rulebook (not going to dig in the closet trying to find mine, but the vehicle design chapter would be the best bet), it says what the volume of a vl (volume liter) is. If I remember correctly, it says 1 vl is equal to 10 liters, but there is other places that point to 1 vl = 1 liter. 1 cubic meter of water is 1000 liters, so depending on which number you use that is either 100vl or 1000vl.

 

[aramis]

In the YIARN CAARDEE Vehicle Catalogue, there is continual references to a standard of weight and volume referred to as "vl". Nowhere is "vl" defined in terms of volume. What exactly is it?

There is also the comment that



One metric ton of fresh distilled water at a specified temperature equals one cubic meter of volume. There is no "about" to it. A cubic meter of salt water weighs slightly more than one metric ton, approximately 1.026 metric tons. One long ton, 2240 pounds, of salt water occupies 35 cubic feet, which gives the submerged volume of the ship, and also the weight of the ship in long tons. When specifying the displacement of a ship, you need to be careful to specify whether you are using a metric ton or a long ton. The difference in weight between fresh water and salt water means that a ship will ride deeper in fresh water than salt water, as fresh water is less buoyant.

Lastly, there is the statement that



The 1943 Half-track CARRIAGE, MOTOR, MULTIPLE GUN, M16 with a quad powered .50 caliber machine gun mount had a gross weight of 19,800 pounds. The 1953 DUKW had a gross weight of 20,055 pounds, so very close to the same weight. The Half-track, when boxed for transport by cargo ship, had a volume of 1188 cubic feet. The volume for the DUKW, uncrated, was 2260 cubic feet. In 1943, the listed gross weight for the DUKW was 19,800 pounds. There is no hard and fast rule for volume verses weight in ground vehicles, and for buses, the cubic footage for volume is even higher than the DUKW. Conversely, the M4A4 Sherman tank had a combat weight of 71,900 pounds, and a shipping cubic volume of 1,529 cubic feet.

10 L (T20 B2 p.223)

 

[Timerover51]

Thanks for the answers. As the vehicle book states that a vehicle has 1 vl per kilogram of weight, that would equate to 1 kilogram per 10 liters. Ten liters of water weighs 10 kilograms, so this would make all vehicle considerably lighter than water.

In the example of the M4A4 Sherman tank cited about, 71,900 pounds equates to 32,613 kilograms. Using the 10 liters per kilogram, that would give the tank a volume of 326,613 liters, or 326.6 cubic meters. Converting that to Traveller dTons at the more precise 13.5 cubic meters per ton, that would be 24.19 Traveller dTons, or about one-fourth the volume of a standard Scout Ship. That would also equate to 11, 529 cubic feet, using 35.3 cubic feet per cubic meter.

 

[tjoneslo]

There is also the comment that

Because water occupies about one cubic meter per metric ton, the displacement tonnage also defines the volume of the ship below the waterline.

One metric ton of fresh distilled water at a specified temperature equals one cubic meter of volume.

Yes, pure water at standard pressure, temperature, and gravity is one metric ton per cubic meter. However the "Displacement tonnage" of ships is based upon their displacement (approximately) in salt water. Water not under conditions of standards pressure and temperature can vary in volume by as much as 9%. If you add impurities (e.g. salt or other dissolved minerals). This again changes the ratio of mass to volume.

Lastly, there is the statement that

a vehicle's loaded weight in kilograms is equal to its size in vls.

<snip example>

This is an abstraction and definition from the T20 design rules. The vehicles are build using VLs. As it says in the same paragraph:

The volumes (vls) used by the T20 vehicle design system represent both weight and volume. This is an abstraction to make the vehicle design process easier and faster.