Faster-than-light interstellar travel in the Star Frontiers setting can be canonically accomplished through one of two methods, depending on the ruleset being used; Alpha Dawn presents a hyper-simplified system where one light year equals one day of travel, which is extremely simple to use, but has no in-universe explanation for the relationship. On the other hand, Knight Hawks details how ships can travel faster than the speed of light; unfortunately, this method (entering "The Void" upon reaching 1% the speed of light) is incompatible with the method presented in Alpha Dawn, since the same velocity must be achieved regardless of the distance of travel, meaning that traversing one light year does not take up significantly more time than traversing 15 light years.
Ships capable of accelerating to Void velocity (sometimes called "jump speed") are called Starships.
The discovery that allows the members of the four races to expand beyond their home worlds and enter the Frontier was purely accidental; it occurred when spaceships were developed that could accelerate to a velocity of about 12 million km per hour (1% of the speed of light): at this velocity, a unique reality of space becomes apparent: in defiance of all previously accepted laws of physics, a ship will disappear from the space known as "the universe" and enter a hyper-dimensional region called "the Void."
Time is very distorted in the Void, and space does not seem to exist at all. If a ship decelerates slightly while in the Void, it will emerge into the "real" universe at some point far distant from where it left normal space. By carefully coordinating the ship's direction of travel with the length of time the ship spends in the Void (usually 3 to 15 seconds), a navigator can "jump" his ship into the vicinity of another star.
Although this process of jumping through the Void allows ships to cover immense distances in very short times, jumping still takes several days. Most of this time is spent accelerating to jump speed and then decelerating at the other end.
Theoretically, a ship can jump any distance across the Void. The limiting factor is the precision needed in the pre-jump calculations. When a ship jumps more than 15 light-years, there is a 10% chance per additional light-year that the ship will misjump. If the astrogator is risk-jumping, this probability is subtracted from his chance to guide the ship safely.
Acceleration to Jump VelocityEdit
Commonly known as "boosting" (outbound) or "transiting" (in-system and inbound), ships accelerate at a steady 1g, generating artificial gravity throughout the ship. After completing the jump, the ship turns over (in an maneuver known as an "end-over") and decelerates at a steady 1g, again generating artificial gravity throughout the ship.
The velocity needed to enter the Void is 12,000,000 kph (3,333,334 m/s).
- At 1g (9.90665 m/s/s) it takes 94.42 hours to reach void velocity (4.72 Standard days = 4 days, 14 hours, 24 minutes).
- At 1g, it will take little under 9.5 Standard days to cross ANY interstellar space; from 1 LY to 21LY. This in addition to the time needed to plot the course.
- At KH game scale, it takes little over 3:20 minutes to reach Void velocity at 1 ADF, though this would not be at all survivable by the crew and passengers.
- At KH game scale, even chemical drive ships can easily reach Void velocity.
- Alternative Hex/Turn Size/Length: 6 km Hex / 10 min turn = 1 ADF = 1g
Fuel Usage and Engine MaintenanceEdit
Accelerating at 1g to Void velocity consumes large amounts of fuel and the constant acceleration exerts massive wear and tear on the ship's engines.
Chemical-propulsion engines simply do not have the fuel capacity to reach void velocity on their own.
If equipped with an astrogation program and properly programmed, a chemical-drive-equipped spaceship could be ferried to near-void velocity by a ship equipped with atomic or ion drives and released in order to enter the void on its own, but deceleration at the destination system would be problematic. For this reason, Chemical-drive ships are never used to cross the Void.
Ion drives are, by far, the most common and practical method of reaching Void velocity, crossing the Void and decelerating at the destination system.
With each engine consuming 1,113 fuel units of Hydrogen per engine per jump, fuel costs are higher than in a comparable atomic-drive ship, (10 Cr per fuel unit = 11,130 Cr/engine/jump), but the ability to use alternative fuels for half the acceleration over double the time AND with no need to overhaul each engine after every 1, 3 or 12 jumps, ion drive ships are more economical to use in a wide variety of commercial applications.
Atomic drives are the most powerful engines available for mounting on a starship, capable of accelerating at several g's in both transiting and combat situations, but despite their romantic appeal are the least practical method of transiting the Void.
Each engine uses up one 10cm diameter pellet of atomic fuel per jump; half on acceleration to Void velocity and the other half in deceleration. Each pellet costs 10,000 Cr. This would make it seem that it is more economical to run an atomic drive starship, however, atomic engines require overhauls that consume man-hours of labor (as much as 60 man-hours per engine per jump), which has costs in both time and manpower (money). The inability to use alternative fuels also works against the practicality of atomic engines, as rules of supply and demand may affect the local supply of atomic fuel pellets.
Sublight Interstellar TravelEdit
While theoretically possible, slower-than-light (or "sublight") interstellar travel is terribly impractical; taking a minimum of one hundred standard years to cross a single light year. Because of this, and the ease upon which any ship can enter the Void, only ancient pre-Frontier generational ships of the type launched prior to the discovery of the Void attempt sublight interstellar crossings.
- ↑ Star Frontiers Knight Hawks Expanded Rulebook, pp. 3
- ↑ Star Frontiers Knight Hawks Expanded Rulebook, pp. 31
- ↑ These calculations have a practical duration of approximately 1 hour per light year plotted (i.e. a 4 LY jump’s calculations are good for 4 hours), before the relative motion of the two stars and the relative positions of the departing ship and the target world begin diverge to the point where new calculations are required. This is called the "jump window". These additional calculations require one hour of plotting for every hour the calculation has expired (round down). Example: a 4 LY jump's coordinates take 40 hours to calculate and are good for 4 hours after that. If 5 hours after the calculations are completed, the ship has not used its launch window, it is considered to be risk-jumping with nine hours of plotting per LY (since the total rounds down) and would require an hour of calculations per light year to return to standard.
- ↑ See also: Buying plotted jumps from third parties
- ↑ The rules for plotting a new course preclude the possibility of plotted jumps over 21 LY; this by a level 6 Astrogator with advanced equipment.
- ↑ "One turn in this game represents 10 minutes of time. Each hex is 10,000 kilometers across." (Star Frontiers Knight Hawks Basic Rulebook pp. 2)
- ↑ Using KH game scale, 1 ADF equals 16,666 meters per second squared. Since 1g = 9.80665 meters per second squared, 1 ADF equals approximately 1,700g's, which is absolutely not survivable for any known sentient species.
- ↑ 556.52 10-minute KH game turns = 94.42 hours = 4.72 days