[Spaceships] Starfire to GURPS conversions? (revisited)

[DaltonS]

Reactionless Drives (TL9^) [REAR!]
This would be more accurately described as a “Reactionless (Star)Drive” with “Drive Field”, “Pseudo-Velocity” and “Boost Drives” design switches. Since it allows travel at c-fractional speeds (1 speed level=1/120 c = 2,500 kps = 1,550 mps = 30 c-seconds/hour) in deep space it quickly replaces all other types of space drive for interplanetary (and later interstellar) travel. Maximum speed is limited by the engine type, its tech level and the ship’s hull size (larger hulls are slower). After that point, additional systems are only useful a spares unless the ship’s effective tonnage is increased by towing or carrying (externally) other vessels.

Reactionless Drive Types

• Inertialess (Late TL9^) - This is typically the first reactionless drive invented. It has a sensor blindspot 60° directly aft (120° on a speed optimized hull). This is a military system.
• Commercial (Late TL9^) - The commercial engine, also know as the commercial drive, is designed for high reliably and superior speeds for long haul trips. This is a direct spinoff of Inertialess drive and has the same sensor blindspot.
• Tactical (Early TL10^) - These operate much the same as Inertialess engines. For the advantage of faster tactical speed (and essentially controlling the fighting range), they sacrifice strategic speed, transit effectiveness, Long Range Weapons range, and have a larger blindspot (120°/180°). Each full size system can boost 1.5 speed levels, so smaller SM systems are often used.
• Gravimetric (Early TL11^) - Scientists figured out how to manipulate the drive-field to create an imbalance in the gravity field just outside the drive-field that will push or pull the drive-field. These new drives have higher power ratios, faster strategic speeds, no true blindspot, and quicker turning. But this comes at a cost: weapons fire is more difficult through the gravity imbalance (–1 for firing in the rear and forward 60° arc (120° for speed optimized hulls), the overall strength of the drive-field is reduced making the the maximum speed 3 levels slower compared to Inertialess drives at the TL period. Each full size system can boost 2 speed levels, so half-size systems are often used.
• Cosmic (Mid TL11^) - After extensive research, the Cosmic drive was developed, powered by Cosmic power points from a specially designed Vacuum Energy Power Plant (GURPS Spaceships 7, page 16). These drives are designed to push a drive field equipped hull at a rapid pace for very few hull spaces. The engine blindspot is 120° (180° for speed optimized hulls). Each full size system can boost 3 speed levels, so smaller SM systems are often used.

            Table 6: Reactionless Drive Types           ||
Reactionless    When      Speed Factors         Cost    ||    Movement Points Scale
Drive Name    Invented  Base  Max  Cruise TSA  Same As  ||    Turn      Hex Size in
Inertialess   Late TL9    1  11-SM   1/2   +0  Standard ||   Length  c-sec. miles   AU
Commercial    Late TL9   0.5  9-SM    1    +2   Rotary  || 20 seconds 1/6  31,000 0.0003
Tactical     Early TL10  1.5 13-SM   1/3   -1    Hot    ||  1 minute  0.5  93,000 0.001
Gravimetric  Early TL11   2  13-SM   3/4   +4    Super  ||  3 minutes 1.5 279,000 0.003
Cosmic        Mid TL11    3  19-SM   1/3   +5   Subwarp || 10 minutes  5  930,000 0.01

When Invented - GURPS tech level this drive was introduced at. These levels have been subdivided into Early, Mid and Late periods, with each period representing a generation of tech development. (Ex. Tactical drives at Early TL11 are 4th generation.)
Base - speed level per system installed. This doubles at the first full tech level after introduction (Ex. Late TL10 for Inertialess and Commercial).
Max - Maximum tactical speed at the time of introduction adjusted for the size of the ship. This increases 1 level per drive generation (1/2 a level for Commercial drives). (Example: a 4th generation Tactical drive has a maximum speed 3 levels higher than that of a 1st generation Gravimetric one of the same TL period.) This can increased slightly by DeTuning the engines. If the maximum speed is 0 or less, the drive may still be used in Standby Mode.
Cruise - Maximum Strategic (safe cruising) speed as a fraction of Tactical speed. Maximum LOD (low detection) speed is half that.
TSA (Transit Size Adjustment) - A drive’s TSA reduces the ship’s effective transit size by 1 SM for each level. An additional level is added to the TSA for each generation of drive and for speed optimized hulls.
Cost Same As - Reactionless Drive Type cost as per GURPS Spaceships page 24.

Dalton "whose ideas may be warped, but to the point" Spence