Name:  Light Fusion Engine
Type (Category):  Engine (Core)
Reference:  TechManual (p. 214)

Description:
Massive technological advances (for the era) made it possible to deploy relatively inexpensive fusion-based power supply systems small enough for vehicular use in the early twenty-first century. Naturally, one of the first applications of this technology appeared in military vehicles and aircraft. In the millennium since that time, combat fusion engines have only grown smaller, more efficient, cleaner and more powerful—enabling the practical development of the BattleMech as the titan of war it has become. Still by no means cheap to the average consumer, battlefield-rated fusion engines are manufactured across the Inner Sphere today by a relatively small number of producers. They range in mass from the half-ton (and incredibly rare) Omni-10 power plant to the truly massive (and rarely used) LTV-400, which tips the scales at 52.5 tons.

In practical application, these engines have evolved as technologies expanded, but they have proven most efficient when used to power BattleMechs (or IndustrialMechs). Combat Vehicles, by comparison, have to mount additional shielding and power conduits to handle and harness a fusion power source, which tends to add significant weight over and above the traditional ’Mech versions.

With centuries of warfare, of course, the best technological enhancements focused on these units, yielding to date three major improvements to battlefield fusion: the extralight (XL) engine, the light fusion engine and the ProtoMech engine.

Light engines were originally the brainchild of the Wolf’s Dragoons mercenary command, as an effort to mimic the compact but lighter-weight Clan XL. This engine, which balances the XL’s bulk and weight savings, tends to weigh 25 percent less than an identically-rated military-standard fusion engine, for the same volume as a comparable Clan-made reactor. Spies from the Lyran Alliance reportedly stole this technology in the late 3050s, and—despite the threat of the Dragoons’ ire—the armies loyal to then-Archon Katherine Steiner-Davion began to field light engines in 3062.

Game Rules:
Engines are considered active in game play unless the unit is shut down or destroyed. Filled or partially filled engine fuel tanks (where applicable) are considered always live and will explode per standard rules if critically hit during game play.

’Mech fusion engines have 3 points of shielding. Each critical hit to an engine slot destroys 1 point of shielding. As shielding is destroyed, the amount of heat escaping from the ’Mech’s fusion drive increases.

The first hit increases the ’Mech’s heat build-up by 5 points per turn. The second hit results in 10 (total) points of added heat build-up per turn, and the third critical hit to an engine slot shuts down the engine and puts the BattleMech out of commission for the rest of the game. Though XL and light engines take up additional slots (in the side torsos), critical hits to any three engine slots also shut down XL and light engines.

A ’Mech is considered destroyed and out of the game if it suffers three engine hits (remember to count engine slots in the side torso if the torso is destroyed).

BattleMechsCombat Vehicles

Prototype Date:	~3055
Production Date:	3062
Extinction Date:	—
Recovery Date:	—

BattleMech Specific Construction Rules

WEAPONS AND EQUIPMENT COMBAT AND CONSTRUCTION TABLE * See rules for this equipment
ER = Engine Rating
TT = Total Unit Tonnage

RULES LEVEL PROGRESSION TABLE
MegaMek Output → Critical Slot:  Fusion Engine
Record Sheet Output → Critical Slot:  Light Fusion Engine

Prototype Date:	~3055
Production Date:	3062
Extinction Date:	—
Recovery Date:	—

WEAPONS AND EQUIPMENT COMBAT AND CONSTRUCTION TABLE * See rules for this equipment
ER = Engine Rating
TT = Total Unit Tonnage

RULES LEVEL PROGRESSION TABLE
MegaMek Output → Critical Slot:  Fusion Engine
Record Sheet Output → Critical Slot:  Light Fusion Engine