Ironsides ASF TRO3050U.png
Production information
Manufacturer Brooks Incorporated
Production Year 2613[1]
Model IRN-SD1
Class Medium aerospace fighter
Tech Base Star League
Cost 3,862,795 C-bills[2]
Technical specifications
Mass 65 tons
Structural Integrity
Frame Lockhead FairFax
Power Plant Thankor 260 fusion engine
Armor SearWeave
Communications System OP/1/2/3.66 Mk IIa
Tracking & Targeting System Ryder Track IV
Heat Sinks 10 double heat sinks
BV (1.0) 1,179[2][3]
BV (2.0) 1,466[4][5][6]


The Ironsides was designed in 2613 as a heavily armed medium aerospace fighter. Its manufacturer, Brooks Incorporated, offered 500 prototypes of the design to any command that wished to field-test the design; as such, examples of the Ironsides were deployed by the Star League Defense Force as well as every Inner Sphere power, and even the Rim Worlds Republic. Though a costly ploy for the company, the result was a fighter field-tested in a variety of environments and situations, resulting in the production model having few if any bugs.[7]

As a medium fighter, the Ironsides is lightly armored with 11.5 tons of StarWeave standard armor, but it carries impressive firepower for its weight class. This is thanks in part to the IRN-SD1 engine, which uses an alignment system to shift the engine's position relative gravitational and velocity influences, to produce an design more compact than others while having the same power-to-weight ratio. The craft's only other design flaw was an inadequate cooling system of only 10 double heat sinks and limited ammunition stores, lending the Ironsides for use mainly in quick-strike missions thanks to a devastating first-strike capability.[7][4]

As is true elsewhere, production of the Ironsides would suffer during the Succession Wars, with an initial five factories reduced to one by 2910. The Carver V plant would eventually be shut down as a cost-saving measure, and by 3050 most Ironsides still located within the Inner Sphere were family heirlooms or museum pieces. The Carver factory would be reopened by the Word of Blake at a later date to produce superior variants to fight in the Jihad.[4]

Weapons and Equipment[edit]

The wide range of weapons mounted on the Ironsides allowed it to fill many of the gaps in fighter technology of the time. Its primary weapon systems are five Yaeger-6 SRM-6s, two in each wing and one in the nose, which can be targeted in groupings from the individual launchers or separately to maintain a spread. However, limited storage space means there is only one ton of ammo, which is just enough for 3 salvos from each of the 5 launchers. These SRMs are backed up by paired Ringer Technologies Model 1 PPCs also in the nose, which use high-density chamber coils to create a narrower beam that will not disrupt the SRM's flight path. The narrower beams also concentrate firepower on a smaller area, though these hot-running weapons are partly responsible for the fighter's poor heat management. Finally the Ironsides has two wing-mounted Allied Technologies Model 2 medium lasers, which have proven to be a constant thorn in the fighter's sides; extensively firing these lasers can rupture the power-chain housing which controls the flow of power to the weapons, resulting in an explosion and considerable damage to the wing structure. Three recall efforts failed to eliminate the problem, resulting in many modern pilots having little respect for the fighter.[7][4]

The weapon systems in the Ironsides are controlled by the Ryder Track II targeting system, which is able to not only independently track targets from sensors placed in several locations throughout the fighter rather than a single, central cluster, but also allows an alpha strike without disrupting any of the individual systems' effectiveness.[7][4]


  • IRN-SD1b 
    The IRN-SD1b Ironsides, designed and deployed exclusively for SLDF Royal commands, saves space by installing an XL engine. The craft increases the SRM ammunition by one ton, adds CASE and five additional double heat sinks, and upgrades the PPCs to ER PPCs[8]. BV (2.0) = 1,653[9]
  • IRN-SD1b-EC 
    Introduced by Clan Steel Viper this variant replaces the SRM-6s with prototype Streak SRM-4s. (Note: EC is an abbreviation used by historians to designate "Early Clan" designs.)[10] BV (2.0) = 1,996[11]
  • IRN-SD2 
    A rare variant of the Ironsides, the IRN-SD2 mounts three large lasers in the nose section in place of the PPCs, with the extra room allowing for an additional ton of SRM ammo. This resulted in a longer endurance during skirmishes.[12]. BV (2.0) = 1,388[5][13]
  • Ironsides CX-19 
    This ComStar-built variant combines Clan and Inner Sphere technology. The craft carries seven Streak SRM-6 launchers backed by two tons of ammunition, while additional firepower comes from five Clan-spec ER medium lasers. Engine performance and armor protection remain unchanged.[16]

Design Quirks[edit]

The Ironsides CX-19 variant is subject to the following Design Quirks:[16]


  • Author Blaine Lee Pardoe stated in a blog entry that, according to his memory which he admitted could be wrong, the Ironsides was among the aerospace fighters for which he wrote the original background as initially published in TRO:2750; for some of these he also designed the stats.
  • In German products, the unit's proper name was translated to Eisenbeiß, which roughly translates Iron Bite. The model code was accordingly changed to ESN-BS1.



  1. MUL online date for the Ironsides
  2. 2.0 2.1 Combat Operations, p. 107
  3. AeroTech 2 Record Sheets, p. 110
  4. 4.0 4.1 4.2 4.3 4.4 Technical Readout: 3050 Upgrade, pp. 240-241, "Ironsides Fighter Profile"
  5. 5.0 5.1 5.2 Master Unit List: Battle Values, p. 180
  6. Record Sheets: 3050 Upgrades Unabridged (Clan & Star League), p. 349
  7. 7.0 7.1 7.2 7.3 Technical Readout: 2750, pp. 74-75, "Ironsides Fighter Profile"
  8. Technical Readout: 3075, p. 169, "Ironsides Variant"
  9. Record Sheets: 3075 Unabridged - Age of War, p. 41
  10. Technical Readout: Golden Century, p. 62
  11. Technical Readout: Golden Century, p. 141
  12. Record Sheets: 3050 Upgrade (Clan & Star League), p. 298
  13. Record Sheets: 3050 Upgrades Unabridged (Clan & Star League), p. 350
  14. Record Sheets: 3050 Upgrade (Clan & Star League), p. 299
  15. Record Sheets: 3050 Upgrades Unabridged (Clan & Star League), p. 351
  16. 16.0 16.1 Experimental Technical Readout: ComStar, p. 14