5 Minute Mechs: The Sentinel

The Sentinel was introduced in 2651 by the Lyran Commonwealth to fill out their BattleMech forces.

The STN-1S would be a popular export model, as it brought a diverse mix of firepower to a 40-ton chassis with its Class 2 autocannon, four-tube SRM launcher, and a small laser.

This mix of weapons made the Sentinel a trooper that could act as a long-range sniper.

It was decently protected with six tons of armor.

Within a year, the Star League Defense Force had orders in with Defiance Industries to produce an advanced version of the mech, which would be the 3L model.

The 3L would keep the top speed of 97 kilometers per hour and upgrade the weapons with a Class 5 ultra autocannon and replace the four-tube missile launcher with a highly accurate two-tube Streak SRM launcher.

In order to make these changes work, two heat sinks were sacrificed, as well as a half ton of armor.

The 3L did act as a wedge between the Commonwealth and the Star League as a whole, as the SLDF tightly guarded the rights to the 3L, a Lyran-built mech, forcing a painfully slow rollout of this variant to the Lyran Commonwealth Armed Forces.

Otherwise, the Sentinel served the Star League and eventually many of the Great Houses.

Eventually, the SLDF procurement department and armament, and the armaments and engineering bureaucracy in the SLDF would reexamine the Sentinel's potential as a sniper.

In 2715, the Star League Royal Divisions would take possession of the first delivery of the STN-3LB Sentinels, which came from these efforts.

The 3LB turned the Sentinel into a deadly sniper platform by replacing the 240-rated fusion engine with an extra-light engine.

It also removes the Streak SRM 2 launcher and the Ultra Autocannon 5 and replaced them with a medium laser in the right torso and a massive Gauss rifle in the mech's left arm.

This upgrade gave the Sentinel exceptional reach and hitting power when compared to other mechs of a similar size.

In addition, the 3LB upgraded the mech's armor with seven and a half tons of Ferro-Fibrous armor.

The Royal Sentinel was only meant for the SLDF, though it did somewhat make it into the hands of the DCMS in limited numbers and can today be found serving as a second-line mech with Clan Hell's Horses.

During the Succession Wars, the 3K series would develop out of chassis left behind when the SLDF departed the Inner Sphere.

The 3K preserved as much of the 3L as possible, with an SRM 2 autocannon five and small laser filling out its weapons payload.

The weight saved would allow the 3K, 3K to carry six tons of armor protection.

The 3KA and 3KB would also be put into service as refits for aging 3L models.

The 3KA would replace the autocannon of the 3K with a large laser, three heat sinks, and two additional tons of armor, while the 3KB would replace the autocannon with a particle projection cannon and three heat sinks.

Even with these downgrades to keep the mech in service, all these were virtually extinct by the time the clans started their invasion, with some meeting their ends at the descendants of the SLDF that had left them behind so long ago.

As the old Sentinels were dwindling and the 3K series was finally coming to an end, Defiance Industries would breathe new life into the platform with information gleaned from the Helm Memory Core and begin production of the 3M model in 3035.

Based heavily on the 3L, the 3M retained much of the older design with an Ultra Autocannon 5, backed up by a medium laser and SRM 2.

The 3M carries, carried five and a half tons of armor and filled much the same role as the old Star League model and served until the Republic era.