This article is about the 75-ton BattleMech. For other uses, see Orion (disambiguation).
Production information
Manufacturer Diplass BattleMechs[1]

Kali Yama Weapons Industries[2]

Kali Yama/Alphard Trading Corp.[2]

Production Year 2525[3]
Model ON1-K[2]
Class Heavy
Cost 6,674,500 C-bills
Technical specifications
'Mech type Inner Sphere BattleMech
Mass 75 tons
Chassis KaliYama Chassis
Armor Valiant Lamellor
Engine Vlar 300
Communications System Irian Orator-5K
Targeting Tracking System Wasat Aggressor Type 5
Heat Sinks 10 single
Speed 64 km/h
BV (1.0) 1,069[4]
BV (2.0) 1,429[2][5]


A poor man's Atlas[6]


The Orion was built in 2456 as the first true heavy BattleMech. Originally designed for the Terran Hegemony to maintain its dominance and built on Hesperus II,[citation needed] the Orion is a dependable workhorse design that can handle almost any combat role, thanks to its mix of long and short-range weaponry and its respectable armoring. After the K model was introduced in 2525, the 'Mech first saw combat during the Reunification War and continued to serve the Star League and its Member States for the next few centuries. Perhaps its most famous role was as the personal 'Mech of Aleksandr Kerensky during the Amaris Civil War, and it was while piloting his Orion that the general kicked down the palace doors to take the Usurper prisoner.[6][7]

The inspiration for the Orion's beginnings is said to be a direct result of Operation PROMETHEUS when the Terran Hegemony realized they would no longer be the sole user of BattleMechs. Work began shortly after with the Hegemony Armed Forces requesting machines suited for various combat roles, and the Hegemony's military leadership were soon accepting proposals for competing designs almost simultaneously. With other designs already underway, it would be General Mechanics winning a contract for a proposal that would ultimately become the Hegemony's premier heavy attack BattleMech: the Orion. Ironically, GM had actually unveiled a prototype as early as 2453, but the HAF, while interested at the time, were dismissive as it did not meet the High Command's requirements for speed and armor, and its armament was considered too lackluster for a front-line war machine. GM had returned to the drawing board in the following years, further refining their design by settling for a smaller, less powerful engine to free up weight for additional weaponry. It would not be until GM's third prototype—the ON1-H, which mounted a newly developed class-10 heavy autocannon—that the HAF would finally approve the design one year following Operation PROMETHEUS in 2456. Following the successful introduction of the prototype, the HAF immediately pushed General Mechanics to produce as many Orions as possible. The armed forces of the Hegemony quickly assigned them to BattleMech regiments in whole companies at a time, adding to their growing ranks of Mackies, Banshees, and later Archers and Griffins.[8]

After the fall of the Star League, Kali Yama Weapons Industries took over production of the Orion, building new models from their factories on Kalidasa. This left the Free Worlds League as the only producer of new Orions during the Succession Wars, although the other Successor States were capable of building spare parts to repair their 'Mechs, and meant the Free Worlds League Military was the largest Orion user. When Kali Yama merged to create the Kali Yama - Alphard Trading Corporation, Orion production was started up on Kendall as well.[6][7] The League's dominance in new Orions began to change during the Clan Invasion when the Successor States met on Outreach and agreed to work together to combat the Clans. Kali Yama/ATC was among those companies which agreed to sell war matériel, including the Orion, to the other States undergoing Clan attacks. In spite of the design's age it still finds itself utilized extensively on the modern battlefield and new variants continue to be produced.[9]

Weapons and Equipment[edit]

The Orion has a varied weapons mix. The 'Mech's primary long-range weapon is a KaliYama Death Bloom LRM-15 launcher mounted in the left torso along with two tons of reloads. While an accurate weapon useful against both land and air targets the system's control cables travel through a narrow area in the shoulder. This area is potentially subject to excessive heat, which can cause either the weapon or actuator to shut down. For intermediate ranges, the Orion carries a KaliYama Class 10 Autocannon/10 in its right torso with two tons of ammo. For centuries the ammunition feed to the cannon suffered regular jamming unless pilots loaded nineteen salvos instead of the full twenty in the ammunition magazine. This defect was eventually solved in the 3030s by Norse-Storm BattleMechs, although the fact that the weapon's placement limits right-arm movement and can be knocked out of alignment if accidentally struck couldn't be helped. Finally, for close-range combat, the Orion has an Irian Weapons Works Class 4 SRM-4 launcher in the left torso fed by a one-ton bin of ammo and two Irian Weapons Works medium lasers; one in each arm.[6][2]

Carrying fourteen and a half tons of armor gives the Orion superior protection to most other heavy 'Mechs, with its chest and rear torso being the most and least protected respectively. Combined with an average cruising speed of 43.2 km/h the 'Mech is a challenging opponent. Only ten heat sinks mounted in the engine leaves the Orion vulnerable to overheating but experienced pilots know to avoid this issue by alternating weapon firings. Technicians love the Orion, because its spacious interior makes performing repairs and maintenance far easier than many other 'Mechs; this is also the reason for the design's longevity.[6][7]

Original Configuration[edit]

When first introduced in Technical Readout: 3025, the ON-1K Orion was given conflicting data. It was described in the text to carry 25 salvos ("rounds") for the SRM-4 launcher, mounted in the left arm, and feature 14.5 tons of armor which gives maximum armor cover on its frame (231 points, with the 232nd armor point allowed from 14.5 tons of armor going unused). However, at the same time its stat block described the SRM-4 launcher as left torso mounted and gave it 1.5 tons of SRM ammunition for a total of 37 salvos, and (only) 14 tons of armor, with altogether 7 less armor points, 224 versus 231, over the accepted configuration. Specifically, each arm was given 21 instead of 24 armor points and the rear center torso armor was given 9 instead of 10 points. A record sheet for this earlier version of the ON-1K with 224 armor points and 37 salvos of SRM-4 ammo was published in the record sheets booklet in the 1987 BattleTech Reinforcements boxed set. Notably, rules at the time did not allow for SRM ammunition to be allotted in anything but 1-ton increments so the design with 1.5 tons of SRM ammunition was illegal under the construction rules.

The canonicity of this version is arbitrary. Because the description and record sheet were published in canonical sources and never technically redacted, they could arguably be regarded as (still) canonical as a subvariant of the ON-1K.

The ON-1K was omitted in the 1991 Record Sheets Volume Three: Heavy 'Mechs publication (while its variants ON-1V and ON-1VA were included).


  • ON1-C 
    The original primitive Orion 'Mech as it was first commissioned lacked an LRM launcher and used an Autocannon/5 in place of the AC/10.[7] A massive 360 engine allowed the 'Mech to obtain a maximum speed of nearly 64.8 km/h, however there was not enough saved weight to mount additional weaponry besides two medium lasers, one in each arm. In addition it only mounted 14.5 tons of armor, and ultimately would be considered too lightly armed and armored with the prototype dismissed as a candidate for production.[8] BV (2.0) = 973[10]
  • ON1-C 2 
    A mixed technology design, built to reduce the strain on Clan Wolf's Inner Sphere production lines, the C 2 utilizes Inner Sphere structural components and predominantly Clan weaponry. Having felt the sting of Inner Sphere 'Mechs mounting extended range LRMs, designers chose to mount an Extended LRM-15 in the typical left torso mount. The rest of this design's weaponry is Clan grade including an ER Large Laser that replaces the typical ballistic mount in the right torso. A Large Pulse Laser is carried in the left arm, while an ER medium laser is in the right. A Streak SRM-4 sits below the LRM in the left torso. One ton of streak ammo, and three tons of LRMs are stored in a CASE II protected magazine in the left torso. Twelve double heat sinks are utilized. BV (2.0) = 2,026[11]
  • ON1-H 
    Built by General Mechanics, the ON1-H was the third known primitive prototype of the Orion 'Mech that was eventually accepted for mass production in 2456. While slower than the first iterations, with a top speed of only 54 km/h (the same as that of a Mackie or Banshee), due to the inclusion of a smaller 275-class engine, the additional weight saved allowed the designers to mount far more firepower. A newly developed Class-10 Prototype Autocannon was installed with two tons of ammo in place of the AC/5. This was backed up by two 5-tube Long-Range Missile launchers with one ton of reloads in the left torso for striking enemies at range and a short-range SRM-4 missile launcher and a ton of ammunition installed in the left arm for close-in defense. It was also heavily protected by 21 tons of armor. A minimal amount of heat sinks, however, could cause buildup of heat within crippling levels, but could be avoided by competent MechWarriors.[8] BV (2.0) = 1,199[12]
  • ON1-K 
    Besides the standard ON-1K variant with 25 salvos of SRM ammunition and maximum armor, an otherwise unnamed (in the sense of not distinctively named) subvariant of the ON-1K may or may not exist that carries slightly less armor, and 37 SRM salvos; see Original Configuration above.[13]
  • ON1-MA 
    This is one of the many minor variants of the ON1-M model introduced in 3052. The Narc Missile Beacon is removed to allow a larger SRM-6 to replace the four pack. Both missile racks also have Artemis IV Fire Control System to increase accuracy. Finally, medium pulse lasers are mounted in place of the original mediums.[9] BV (2.0) = 1,501[16]
  • ON1-MC 
    A third minor variant of the ON1-M also introduced in 3058. The designers removed both missile racks and Narc launcher to make room for Medium Range Missiles. In place of the LRM-20 is an MRM-20 while a larger MRM-30 is crammed in the torso where the SRM-4 formerly sat. Enough room is left to add a head-mounted C3 slave unit. This variant was much-used by the Draconis Combine.[9] BV (2.0) = 1,501[18]
  • ON1-MD 
    Another minor variant of the ON1-M, fielded in 3062. A simple weapon swap, the LB-X Autocannon/10 is exchanged for a rotary autocannon/5. BV (2.0) = 1,597[19]
  • ON1-M-DC 
    Introduced in 3053, this 1-M subvariant trades one ton each of SRM and Narc ammunition plus one double heat sink for a Command Console. BV (2.0) = 1,444[20][21]
  • ON1-V 
    A basic modification of the ON1-K first seen in 2799, the ON1-V moves the left-torso SRM-4 to the left arm and removes three tons of armor to make room for an additional SRM-4 launcher in the right arm in order to give the Orion even greater close-range damage capability.[2][6] BV (1.0) = 931,[14] BV (2.0) = 1,298[22]
  • ON1-VA 
    A modification along the same lines as the ON1-V introduced in 2901 the VA model also moves the left torso SRM-4 to the left arm, but removes the LRM launcher rather than armor, to add the second SRM-4 launcher, sacrificing some long-range damage capabilities for superior close-combat capabilities.[2][6] BV (1.0) = 1,111,[14] BV (2.0) = 1,328[23]
  • ON1-V-DC 
    This command subvariant of the 1-V, introduced in 2913, trades 1 ton each of LRM/SRM and autocannon ammunition for a Command Console. BV (2.0) = 1,310[24][25]
  • ON2-M 
    The 2M is another upgrade of the Orion using Star League technology. Built in 3063 the 'Mech uses an Endo Steel chassis and utilizes ten double-strength heat sinks to save weight and for their greater heat-dissipation ability. For long-range combat, the ON2-M is armed with a Gauss rifle as well as an LRM-15 linked to an Artemis IV FCS for increased accuracy. For closer ranges, the 'Mech has three medium pulse lasers. The ON2-M is armored with twelve and a half tons of ferro-fibrous armor. BV (1.0) = 1,633[14] (1,624),[26] BV (2.0) = 1,828[27]
  • ON3-MX 
    This experimental Orion 3100 variant was introduced in 3075 as "a BattleMech for the thirty-second century"; although its flaws prevented any immediate production it gave Kali Yama valuable experience and a few prototypes were sold. It is equipped with an experimental Extended LRM-10 and Improved Heavy Gauss Rifle. Three tons of ammunition feeds the LRM launcher while the iHGR gets four tons of ammunition. For close in work, this Orion variant has an ER medium laser in each arm. To provide room for these weapons, the 'Mech has an XL engine, standard armor, and standard internal structure, and only the ELRM ammo is protected by CASE. BV (2.0) = 1,849[28]
  • ON3-M 
    This version introduced in 3083 was based on the earlier ON3-MX, although it addresses some of the shortcomings of that 'Mech and shares many of the same features as the ON1-M. Providing a more balanced weapon suite it still carries an Extended LRM-15 with four tons of ammo and an ER medium laser in each arm but instead uses a Grand Slam Gauss rifle with two tons of ammo in the right torso. It also uses CASE II to protect the ammunition and has a head-mounted TAG system to call in artillery. Initial feedback and advanced orders convinced Kali Yama to switch most of their Orion production lines over to making the ON3-M in 3086, but were soon set back a few years later when pressure from the Republic of the Sphere caused the Federated Suns to cancel their order. The company has seen sold the 'Mech at below-market prices and suffered financial hardship. BV (2.0) = 1,826[29][30]
  • Dual Cockpit refits 
    The Orion is one of the Free Worlds League's preferred 'Mechs on which to install Dual Cockpits. Standard refits usually install the Dual Cockpit on an ON1-V or ON1-M, requiring the removal one ton of SRM ammunition.[33]

Custom Variants[edit]

Apocryphal Variants[edit]

Apocryphal Content Starts

The information after this notice comes from apocryphal sources; the canonicity of such information is uncertain.
Please view the reference page for information regarding their canonicity.

From MechWarrior Online:

  • ON1-P Protector 
    A late 3040s era homage to General Kerensky's custom variant, the Protector carries an almost identical weapons loadout. The only notable difference is its use of a standard PPC in the place of the still-lostech snub-nosed version, dropping the CASE and volume of ferro-fibrous armor carried to free up the weight for the heavier weapon.[35]

From MechWarrior 5: Heroes of the Inner Sphere Expansion Pack:

  • ON1-YAJ Yad al-Jauza 
    Piloted by Aditi Whidbey, who had been driven to madness by a cult known as the Church of Kali, she claimed that the Orion had fallen out of the sky and styled it Yad al-Jauza or "Hand of Orion." The 'Mech is built upon an XL engine. A large laser is mounted in each arm, with the right arm additionally mounting an LRM-10; two LRM-10s are mounted in the left torso, along with another large laser. Fifteen double heat sinks keep the 'Mech cold.[36]

Apocryphal Content Ends

Design Quirks[edit]

The ON1-K Orion and variants, unless specified otherwise, are subject to the following Design Quirks:[37]

The ON1-H Orion variant is subject to the following Design Quirks:[8]

The ON3-M Orion variant is subject to the following Design Quirks:[29]

Notable Pilots[edit]

See: Category:Notable Orion Pilots

Related BattleMechs[edit]

  • Perseus - With a long history of production and deployment of the Orion, plus the 'Mech's noted spacious design, the Free Worlds League used the design as the basis of their first homegrown OmniMech.
  • Pandarus - Similar to the Perseus, this design was intended to be an OmniMech (albeit with a missile boat focus), however budget issues led to Kali Yama building the prototype as a standard BattleMech using a mothballed Orion chassis.


  • The original Orion artwork shows, and the text in TRO:3025 states, that the SRM-4 of the ON1-K is mounted in the Orion's left arm (with two of the six tubes pictured serving as hookup points for connecting with Coolant Trucks). However, the stat block and accompanying record sheet in BattleTech Reinforcements, and all subsequent record sheets, place the SRM-4 in the left torso. This disconnect was resolved with updated artwork created for the 2019 Clan Invasion crowdfunding campaign, which clearly places the SRM-4 in the left torso, and not the left arm.
  • While the description of the ON1-C prototype in Experimental Technical Readout: Primitives, Volume 5 describes that it also mounted an SRM-4, the included Record Sheet does not show this. It is not clear if this was intentional as the profile of the original primitive Orion also describes "three" prototypes. It is possible, but not conclusive, that the SRM-4 version was another test frame of the ON1-C, the first prototype as described, and the included record sheet as the candidate for the second with 3 tons freed possibly for more armor.



  1. Field Report 2765: Periphery, p. 11: "Infrastructural Integrity"
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Technical Readout: Succession Wars, pp. 144–145: "ON1-K Orion"
  3. Era Digest: Age of War, p. 11
  4. Combat Operations, p. 107
  5. Record Sheets: 3039, p. 160
  6. 6.0 6.1 6.2 6.3 6.4 6.5 6.6 Technical Readout: 3039, pp. 152–153
  7. 7.0 7.1 7.2 7.3 Technical Readout: 3025 Revised, pp. 100–101
  8. 8.0 8.1 8.2 8.3 Experimental Technical Readout: Primitives, Volume 5, p. 7: "ON1-H Orion 'Mech Profile"
  9. 9.0 9.1 9.2 9.3 9.4 Technical Readout: 3050 Upgrade, pp. 82–83
  10. MUL Profile for ON1-C includes BV2.
  11. Recognition Guide: ilClan, vol. 19, p. 13
  12. MUL Profile for ON1-H includes BV2.
  13. Technical Readout: 3025: "Orion"
  14. 14.0 14.1 14.2 14.3 Combat Operations, p. 130
  15. Technical Readout: 3050 Upgrade, p. 83
  16. Record Sheets: 3050 Unabridged (Inner Sphere), p. 199
  17. Record Sheets: 3050 Unabridged (Inner Sphere), p. 200
  18. Record Sheets: 3050 Unabridged (Inner Sphere), p. 201
  19. Record Sheets: 3050 Unabridged (Inner Sphere), p. 202
  20. Record Sheets: 3050 Upgrades Unabridged (Inner Sphere), p. 198
  21. MUL online entry for the ON1-M-DC variant
  22. Record Sheets: 3039, p. 161
  23. Record Sheets: 3039 Unabridged, p. 162
  24. Record Sheets: 3039, p. 163
  25. MUL online entry for the ON1-V-DC variant
  26. Record Sheets: Upgrades, p. 130
  27. Master Unit List: Battle Values, p. 132
  28. Experimental Technical Readout: Marik, p. 5
  29. 29.0 29.1 Technical Readout: Prototypes, p. 133
  30. Record Sheets: Prototypes, p. 73
  31. Technical Readout: 3150, p. 223
  32. Record Sheets: 3150, p. 289
  33. MechWarrior Companion, pp. 51–52: "House Conversions"
  34. Record Sheets: 3050 Unabridged (Inner Sphere), p. 204
  35. MechWarrior Online (video game)
  36. MechWarrior 5: Mercenaries, Heroes of the Inner Sphere
  37. BattleMech Manual, p. 93: Design Quirk Table - Orion Entry