SPACESHIP DRIVES

Three types of spaceship drives (also called engines or propulsion) are available: chemical fuel engines, ion engines and atomic engines. Each of these types has certain limitations and requirements which are discussed in detail here.

In addition to a drive, each ship must have a Drive Program for the on-board computer. Information on Drive Programs is included at the end of this section.

Sizes. Engines of all three types come in three sizes, ranked from size A to size C. Size A is the smallest, and size C the largest. A hull must be equipped with the engine size appropriate for that hull size, as shown on the Hull Size/Engine Size Chart.

HULL SIZE / ENGINE SIZE CHART

Hull Size Engine Size
1 to 4 A
5 to 14 B
15 to 20 C

All engines are equipped with maneuver jet nozzles. These are used to take the ship through delicate maneuvers, such as docking with a station.

Chemical Drives

Chemical drives are the cheapest and simplest spaceship engines. They work by igniting a chemical fuel, and propel the ship with the force of the exhaust. Liquid or solid oxygen must be carried by the rocket. Chemically driven ships must carry a lot of fuel, and cannot accelerate long enough to achieve interstellar speeds.

Any hull that is outfitted with chemical engines must have the full complement of engines for that hull. For example, a ship with a hull size of 13 needs four chemical engines. These engines are mounted at the tail of the ship, instead of away from the ship on struts.

All ships with chemical engines have an ADF of 1.

The Chemical Drive Price Table lists the prices of the three types of chemical engines. Because these engines are simple and easy to build, the cost is the same at all construction centers.

CHEMICAL DRIVE PRICE TABLE

Engine Size Price
A 50,000 Cr
B 100,000 Cr
C 200,000 Cr

Chemical Drive Fuel. Ships using chemical drives burn a load of fuel on every voyage, as a general rule. The cost of one load of fuel is 250 Cr x the hull size of the ship for each engine. This is doubled for shuttles when they are taking off from a planet, because of the extra thrust required to escape the gravity well.

If a chemical drive system ship is being used on a long voyage and the crew wishes to conserve fuel, the referee may allow the players the option of traveling very slowly (a mere 10,000 km per hour or so). They may then be allowed to make a return trip with the same load of fuel that they started with.

Ion Drives

Ion engines operate on the same principle as particle beam weapons, such as a proton or electron beam battery. Charged particles are released from the rear of the engines at tremendous velocity. Even though the particles are extremely small, there are enough of them to provide a ship with a steady and long-lasting thrust. Ion drive engines require very little fuel.

Ion engines must be mounted on struts, away from the hull of the spaceship. Any ship equipped with ion drives must have the full complement of engines for that hull size in order to accelerate and decelerate normally. The ADF of a ship with ion drive always is 1.

Prices for ion engines are listed on the Ion Drive Price Table. Note that ion engines are not available at class III construction centers, and that they are more expensive at class II centers.

ION DRIVE PRICE TABLE

Engine Size Class I Center Class II Center
A 100,000 Cr 150,000 Cr
B 150,000 Cr 200,000 Cr
C 200,000 Cr not available

Ion Drive Fuel. Ion engines work by ionizing (electrically charging) particles of fuel. This fuel can be just about anything, but the standard substance is hydrogen. If characters are stranded in an asteroid belt with an ion-driven ship, however, they could crush up the rock of the asteroids to use for fuel, or basically use any kind of junk that they can find. All fuels other than hydrogen will provide the ship with an ADF of only 1/2.

Hydrogen can be purchased at all SCCs for a cost of 10 Cr per engine per ADF point used. For example, a ship with two ion engines embarks on a voyage with 8 units (8 x 10 = 80 Cr worth) of hydrogen. The ship accelerates to a speed of two hexes per turn, which uses two ADF points. Since both engines burned the fuel, however, this means that four units of fuel have been used. The ship now has just enough fuel to use two ADF points per engine to decelerate at its destination.

A ship with ion drives can carry a tremendous amount of fuel, if necessary. Up to 10,000 units can be stored in each engine. This can be increased if the crew makes a few modifications to the ship's storage areas.

Atomic Drives

The most powerful type of engine that can be installed on a spaceship is an atomic fission engine. Atomic engines propel the ship by splitting atoms and using the tremendous amount of energy released as thrust. Atomic drives use either uranium or plutonium as fuel. An engine will burn a 10 cm diameter chunk of fuel in the course of an interstellar jump.

Atomic engines are mounted on struts that keep them away from the ship's hull. This is because these drives are a source of dangerous radioactivity, and must be isolated from the crew and living quarters of a ship. A fighter is the only ship that has an atomic drive mounted in the spaceship's tail. Fighter pilots must wear special suits that resist radioactivity.

The struts that atomic drives are mounted on are equipped with explosive charges. These charges enable the pilot or engineer to jettison the engines if this should become necessary. This obviously will be done only in extreme emergencies, such as an engine meltdown or overload (see Close Combat for more details).

ADF. If a ship has a full complement of atomic engines, both its ADF and MR wilt be the number indicated on the Hull Specification Chart. For each engine less than the maximum, however, either the ship's ADF or MR (player's choice, at time of construction) must be lowered by 1. The ship's MR cannot be more than one higher than the ADF. Also, fhe ship's ADF and MR never will be less than 1, even if the ship has only one engine.

EXAMPLE: Hargut Lance, a hull size 6 ship, can carry three atomic engines. With all three engines, its ADF is 3 and its MR is 3. If one engine is removed, either its ADF or its MR must be reduced to 2. The owner, Snar Latm, reduces the MR. If a second engine is removed, the ship's ADF must be reduced to 2, or its MR reduced to 1.

Cost. Atomic engines are very expensive, as shown on the Atomic Drive Price Table.

Engine Size Class I Center Class II Center
A 200,000 Cr 250,000 Cr
B 400,000 Cr 500,000 Cr
C 750,000 Cr not available

In addition to the initial cost, atomic engines are more expensive to maintain than either of the other types.

Atomic Fuel. A pellet of atomic fuel is a 10 cm diameter piece of radioactive material, either plutonium or uranium. One pellet costs 10,000 CR. They can be purchased only at Class I or Class II ship construction centers. A pellet is burned out in a single interstellar jump. A ship that does not decelerate appreciably after a jump will still have power for 1d5 x 20 days.

An atomic engine can automatically replace the fuel pellet after a jump, if the engine has been loaded with an additional pellet. Depending on the size of the engine, from 3 to 10 pellets can be loaded into it before a voyage begins. (For the exact figure, see the Atomic Drive Information Table.) Additional pellets can be loaded only by a Spaceship Engineer (see Spaceship Skills). Refueling an engine takes 2d10 hours, minus the engineer's skill level. Because most of this time is spent removing access panels and shielding, the time is the same no matter how many fuel pellets are loaded.

Overhauls. Besides refueling, atomic engines must be overhauled regularly by an engineer. To determine how much time the overhaul takes, roll a number of d10s equal to the engineer's skill level. Subtract the result of this roll from 60 hours. The difference is the number of hours needed to overhaul the engine.

EXAMPLE: A level 3 starship engineer needs to overhaul a starship's engine. The player rolls 3d10 and gets 15. Subtracting 15 from 60 hours determines that overhauling the engine will take 45 hours.

The Atomic Drive Information Table lists the number of trips each type of atomic engine can make between overhauls.

Multiple Engines. If more than one atomic engine on a ship needs either refueling or overhauling, each must be worked on separately. For example, if only one engineer is aboard a twin-engine ship that needs both overhauling and refueling, that engineer must perform four operations consecutively. This could take several weeks.

Skipping Overhauls. If an atomic engine is not overhauled on schedule and the ship tries to make an interstellar jump, there is a 60% chance the engine will fuse itself into a worthless lump of iron. If a second jump is made, this risk increases to 80%. A third jump cannot be made, and an attempt will automatically ruin the engines. If there is an engineer on board, he has a chance to realize that the engines are about to become
fused. This chance is equal to his Logic score plus 10% x his engineering skill level. A successful roll means the engineer can shut down the engines before they are ruined. However, no further acceleration will be possible until the engines are overhauled.

ATOMIC DRIVE INFORMATION CHART

Engine Size Pellets Carried Trips Between Overhauls
A 3 1
B 6 3
C 10 12