Internal fuel capacity can be upgraded up to ten times times in sequence, doubling the cost for each consecutive upgrade. The first time costs 1,000Cr and doubles the original fuel capacity per drive, the second costs 2,000 credits and triples the original capacity, the third upgrade is 4,000 credits and quadruples the original capacity. 8,000cr gets you quintuple the capacity, and 16K credits sextuples the capaicty. 32Kcr nets you septuple capacity, 64Kcr octuples capacity, and 128Kcr nonuples the capacity. 256 gets you the maximum decuple (10X) capacity.

Thus, it would cost 15K credits to quinuple the original capacity (five times the capacity). Note that it gets quite expensive at the higher capacities, high velocity comes with a price. External tankage can not be increased, as this is solely for lifting off from an atmosphere. However, ships launching from an orbital station may factor the external tankage into their MSV. It should be noted that anything five times or more will start chewing into cargo and passenger capacity.

Note that the ADF for a ship equipped with the specifed amount and size drives will be 1. This can be increased by a factor of 1 by doubling the number of drives when applicable (no more than eight drives of any type are permitted, so in cases where doubling the number of drives exceeds eight this increase is not possible), which increases fuel capacity and consumption. Also, supercharged chemical drives have been recently made available which increase ADF by a factor of 1, which can be consecutively figured in (re: a ship that requires two A drives can have four SC drives with an ADF of 3). SC Chemical drives are only available through a military contractor and are double the standard price. Note that doubling the number of drives can only be performed once for increased acceleration by a civilian contractor, further doubling will have no effect unless performed by a military contractor. Again total number of drives must be observed for such increases. Due to the high cost of these perfromacne modifications, unless the players are operating under a corporate or military contract, for the most part any chemical thruster powered civilian vessel will have the standard allotment of drives and corresponding ADF of 1. These game mechanics have been introduced to depict what is possible in the absence of atomic drives rather than what is probable for common use.

Also noteworthy is the deck arrangement of system ships. Streamlined craft (available for system ships up to HS:5) will typically have their decks parallel to the main axis so as to permit movement when on the surface. Larger craft will typically (but not always) have the decks arranged perpendicular to the main axis. The bulk of a system ship's travel time will be spent coasting at zero G, as it will spend less time accelerating to the maximum safe velocity (or any other desired travel speed) than it will coasting along to its destination. Larger craft boasting higher fuel capacities will spend a little more time accelerating than their smaller counterparts, and as such at ADF:1 the crew can travel about the craft under such conditions...but once the desired travel speed is reached it will spend the bulk of the trip in zero G coasting.

Also note that if a ship accelerates past 200 hexes per turn, it will enter the void...but this is unlikely to happen on system ship designs considering the enormous fuel capacities and consumption rates. However, assuming if those prohibitive fuel capacity modifications could be made (remember, it would need fuel to decelerate on the other end), it would possible to convert a system ship into a starship. Realize this is merely a theory, not a rule. Also note that even if the theory could be realized, it is much more cost efficient to use the Ion drives for such duty.

EngineSize	Fuel Capacity	Fuel Consumption Rate	Cost*
A	12u x HS per drive	1u per ADF point expended per drive	25,000Cr
B	24u x HS per drive	2u per ADF point expended per drive	50,000Cr
C	48u x HS per drive	4u per ADF point expended per drive	100,000Cr

* price is the same regardless of SCC size


Ion Drives

Ion drives burn liquid hydrogen (aka L-Hyd), available at any docking station or SCC at the cost of 5Cr per unit. However, an ion drive can burn pretty much any other fuel source incurring a penalty of ½ the base ADF (under most conditions, that translates to accelerating by one hex every other turn unless performance has been modified).

All Ion drives burn L-Hyd at a rate of one unit per ADF point expended. Thus, an interstellar trip would take a minimum of 402 units to complete: accelerating up to the sub-jump velocity of 200 hexes/turn, nudging the craft into the void by accelerating once more, followed by void exit decelration of one, and then resuming normal deceleration of 200 hexes thus coming to a complete stop.

Prototype ion drives are in the works that can scatter the ion field around the ship's entire hull rather than directing it aft as thrust, creating a radar jamming window. However, this hasn't been made available to the public yet as it is still in the experimental stage, there are still a few bugs that need to be worked out. Like the chemical drives, these game mechanics illustrate what is possible rather than probable...in no way should a party have access to the modified "window" ion drives.

Engine Size	Fuel Capacity	SCC:I price	SCC:II price	SCC:III price
A	1,000u	50,000Cr	75,000Cr	100,000Cr*
B	2,500u	75,000Cr	100,000Cr	n/a
C	5,000u	100,000Cr	n/a	n/a

* applicable only to Streel, Inc. owned/produced vessels, treat as n/a for any other application