Photon Torpedoes

The standard photon torpedo used by Starfleet is an elongated elliptical tube constructed of molded gamma-expanded duranium and plasma-bonded terminium outer skin. The completed casing of the Mark XXV measures 2.1 x 0.76 x 0.45 meters, and masses some 186.7 kilograms dry weight, which is slightly less than previous designs. The finished casing is split equatorially by phaser cutters, which also provide penetrations for warhead reactant loading, hard-line optical data network connections, and propulsion system exhaust grills. Within the casing are installed deuterium and anti-deuterium holding tanks, central combiner tank, and their respective magnetic suspension components; target acquisition, guidance, and detonation assemblies; and a warp sustainer engine. The holding and combiner tank shells are gamma-wielded hafnium titanide. The tank liner, as well as the warp sustainer engine coils, are all constructed from directionally cast silicon-copper carbide to maximize field efficiency.

The multi-mode sustainer engine is not a true warp engine due to its small physical size, one twelfth of the minimum matter / antimatter (M/A) reaction chamber size. Rather, it is a miniature M/A fuel cell, which powers the sustainer coils to grab and hold a hand-off field from the launcher tube, and to continue at warp speeds if launched during warp flight by a starship. The cell, a cylinder 20 cm in diameter and 50 cm in length, is limited to a narrow warp field frequency range and cannot add more than a slight amount of power to the original hand-off field. The Maximum Cruising Velocity will follow the formula " MCV = v + 0.75 v / c ", where v is the launch velocity. Other flight modes are triggered according to initial launch conditions. If launched during low-impulse flight, the coils will drive the torpedo up to a 75 % higher sub-light velocity. If launched at high sub-light, the sustainer will not cross the threshold into warp, but will continue to drive the torpedo at high relativistic velocities. If required, the maximum effective range can be extended, but with a loss of detonation yield, as the sustainer engine draws reactants from the M/A tanks.

Once given direct prelaunch trajectory instructions by the optical data network targeting computers, and optionally updated in flight by subspace radio link, the torpedo's targeting and guidance systems communicate with the sustainer to produce the optimum travel time to the target. This allows the arming circuitry a minimum of 1.02 seconds to combine the warhead fuels. Trajectory changes are made by differentially constricting the sustainer exhaust grills.

Photon torpedoes can be directed against threat force targets at distances from 15 to nearly 3,500,000 kilometers from a starship or space station.

Since photon torpedoes are classified as semi-autonomous weapons, initial firing direction is not a major concern. Most firings involve direct fore or aft vectors, within ten degrees of the vehicle centerline. When required, rapid trajectory change may be executed following launch to achieve target acquisition, cruise tracking, and terminal guidance. This is utilized with numerous pre programmed starship maneuvers, momentarily disabling Conn bridge station attitude and translational panel inputs. Targets within twentyfive kilometers involve launch followed immediately by fast breakaway to guarantee that the starship will remain outside the explosion hazard radius, which is variable with yield.