The hellfire torpedo was designed to complement the quantum torpedo.

The principle behind the design of the Hellfire torpedo was simple - most of a torpedo's energy is burnt against the shields of an enemy vessel. The Hellfire was an attempt to circumvent this problem.

The Hellfire was designed to bypass enemy shields and pack a punch to the enemy ship itself. The Hellfire's 'magic trick' is to 'skip' past enemy shielding using subspace phasing technology first used in 2368.

The torpedo has a small, short range sensor array that, as it nears an enemy ship, scans its target's shield 'bubble', frequency and modulation, and then activates the subspace phase transporter. This allows the Hellfire to move out of phase with the target, and re-appear within it's shield parameter, and impact directly on the hull. That sequence takes only a matter of milli-seconds. To the naked eye, it appears the Hellfire actually passes though a ship's shields instead of 'skipping' past them.

The warhead contains protomatter, and this payload is acted upon by antiprotons to cause the violent reaction and deadly explosive force of the weapon. A quantum singularity powers the torpedoes systems and allows it to maintain warp speeds, as well as giving it a distinctive bright green glow. The torpedo has its own warp coils in the casing and therefore is able to maintain a high warp for a fairly long time. However, the torpedo must be fired at warp initially to obtain warp velocity.

The torpedo has no communication device, it is completely self controlled and contained, a 'fire and forget' weapon. This is both a drawback and an advantage to the torpedo because it may lose the target even if the ship doesn't, but it can maintain lock if the ship has problems. Alas, the shield modulation can't be transmitted to friendly vessels. The short range sensor of the Hellfire cannot be modified to do that, the sensors have too limited a range and there isn't enough space for communications gear.

Attempts have been made to fit communicators to hellfire torpedoes in order to acquire enemy shield data, but it was found that the torpedo did not have enough time to send any information. Future versions of the Hellfire may well have a short-range comms device fitted, as this would also make the torpedo better able to cope with changes in the shield modulation because it would reciever the modulation data at the last possible moment.

Since the Hellfire uses a Mk-II Quantum torpedo's casing (originally designed narrower, but slightly longer than a quantum torpedo), the Hellfire had a break-away or sabot casing placed around it to allow it to be fired from a standard torpedo launcher on any ship. This was upgraded in 2377.

Currently the Mark-II Hellfire is under development. The upgrade over the Mark-I is the Mark-II will be able to remodulate it's frequency, allowing it to 'skip' past an enemy's shields easier. This upgrade is still being perfected and far from deployment. Another improvement, now under theoretical review, is for the torpedo to be in a state of temporal flux continually from launch to impact. However this is years from becoming a reality.

• Range Limit: 15 km - 4 050 000 km (from starships at warp)
• Warp Speed: 110% of warp factor of firing ship
• Sublight Speed: up to a 70% higher velocity (maximum velocity = initial velocity + .70 × initial velocity/ c {or Vmax = Vi + .70 Vi/c}
• Shield Scan Range: 6 m
• Developed: 2375
• Operational Since: 2375
• Yield: 350 isotons.
• Warhead: Protomatter that is ignited by and reacted upon by antiprotons.