Combat Frame Data: CF-05

CF-05 Grenzmark C


Technical Data

Model number: CF-05
Code name: Grenzmark C
Nickname: Grenzie
Classification: mass production general use combat frame
Manufacturer: Seed Corporation
Operator: Systems Overterrestrial Coalition
First deployment: CY -5
Crew: 1 pilot in cockpit in chest
Height: 17.5 meters
Weight: dry weight 48.2 metric tons, full weight 65.7 metric tons
Armor type: carbon nanotube-infused ceramic/steel composite
Powerplant: cold fusion reactor, max output 756 KW
Propulsion: rocket thrusters: 40,600 kg total thrust, 180° turn time 1.75 seconds; legs: top ground speed 190 kph
Sensors: Seed Corporation Halo radar/optical target acquisition and identification system mounted under grilled radome "head"
Fixed armaments: none
Hand armaments: 110mm machine gun, 40 rounds per magazine;  heat axe, battery-powered, stored on skirt armor rack

General Notes

In response to rising tensions on earth, Coalition Security Corps Director Sanzen Kaimora contracted with Seed Corp to supply the CSC with combat frames based on maverick inventor Tesla Browning's prototype. The CF-02 Grenzmark I proved highly effective in combating dissidents. However, the CFs' presence heightened grounder hostility and drastically raised the number of attacks on SOC installations.

Sanzen quickly determined that an increase in combat frame quality and numbers was needed. He commissioned Seed Corp to produce a more advanced successor to the Grenzmark I and stipulated a six-month deadline. Browning drew up the basic design for the CF-06 Grenzmark II in a matter of weeks, but Seed Corp engineers realized they lacked the facilities and resources to roll out a mass-production model within the required time frame.

While work commenced in Chicago on a new factory for the Grenzmark II, Seed Corp assigned a team to create a stopgap solution that would temporarily satisfy the Coalition's needs. Their short time frame and limited resources led the team to focus on making incremental improvements to the Grenzmark I instead of designing a new CF from scratch. Three prototypes, designated Grenzmarks A, B, and C, were produced. The Grenzmark C was chosen as the CSC's new front line unit after speedy field trials and was summarily rushed into production.

The results surpassed both the Coalition's and Seed Corp's expectations. Pilots immediately took to the Grenzie's straightforward cockpit layout, easy-to-use operating system, and responsive controls. The Halo sensor suite--an innovation planned for the Grenzmark II and tested on the Grenzmark C--was an instant game-changer, and the Grenzie's improved thrusters and generator gave it noticeably superior combat performance compared to the Grenzmark I. The Grenzie's retention of its predecessor's 110mm machine gun and heat axe greatly eased CSC pilots' transition to the updated model, while techs required little additional training to be rated on the new CF.

The Grenzmark C achieved such lasting popularity that many CSC units kept using the Grenzie for years after the Grenzmark II rolled out. As late as CY 1, Director Sanzen himself maintained Grenzmark C teams to patrol the woods surrounding his private Byzantium colony compound.

Color version:

To see the venerable Grenzmark C in action, check out the firstsecond, and third previews of Combat Frame XSeed, my new mecha/Mil-SF series, coming soon!

Can't wait for XSeed? Treat yourself to mind-bending space adventure and pick up my award-winning Soul Cycle!

The Soul Cycle - Brian Niemeier


  1. Awesome back story and technical data sheet. I hope this will be included in the beginning of the book. Or a note to read about it in the back. Will there be pics to accompany these descriptions for all models?

    There was a typo: "six-moth".

    1. Thanks. I plan to write up data sheets for as many CFs as I can get original art for. They'll be included in the back of the book and on their own web page.

      P.S. Typo fixed.

  2. Brian, you did it right: I want to turn the page and learn more.

    Kids, this is how you do it.

  3. Good summary. Lore is interesting to read.

    1. There's several notebooks' worth more where that came from.

  4. Seriously, if you guys think this mere tidbit of lore is something, you should know the amount of background material I've generated for XSeed rivals or surpasses the world building I did for the Soul Cycle.

    1. Brian, you've encapsulated a smart bit of story into the technical specs and history of the mech frame. Many writers fail pretty miserably in attempting what you accomplished: you advanced the story with tech specs. (I think I hear Boeing on your phone.)

      This just means more sales and cross-licensing opportunities. So sorry for you, man! You'll just have to learn to accept your level of rock-star talent!

    2. Wow. High praise. Didn't realize anybody outside of Japan had tried this.

  5. Propulsion: rocket thrusters: 40,600 kg total thrust

    Note: kg is mass and thrust is force. Since we're metric, we should multiply by 9.8m/s^(2) to get into Newtons.


    Because the same mass has different weights in different gravities. Especially important in space/on different worlds/moons/asteroids, etc.

    But it looks neat!

    1. Good to know. I'm just going by the format used by MAHQ and Jane's, which use kg and lbs for thrust, respectively.

    2. Not to be "combative", but yes we do measure thrust in terms of mass, not force. We just factor out the 32 ft/s^2 (or 9.8 m/s^2) and state the amount of mass we can move against Earth's acceleration.

      May not be that way in the future, or in Brian's world, but it's now the norm.

      How Things Work: Rockets and Thrust

    3. I agree that it is now the norm! We are just on one world going against one particular gravity.

      I was saying that where you're going in multiple gravities (Earth, Mars, Titan, Io, but not Europa), knowing total force might be more useful than mass in Earth's gravity. That's the reason I brought it up.

      In the Torchship books, Karl Gallagher uses acceleration for indicating thrust level, with 1 m/s^(2) = 1 grav.

      Either way, it's Brian's world.

      On the other hand...

      Weight: dry weight 48.2 metric tons, full weight 65.7 metric tons
      Propulsion: rocket thrusters: 40,600 kg total thrust...

      We are not going to see hovering or flying mechs in earth gravity, are we? The rockets can make 40.6 metric tons hover, while dry weight is 48.2 metric tons. Am I reading that right?

    4. "We are not going to see hovering or flying mechs in earth gravity, are we?"

      We will, but keep in mind that the Grenzie is the second-oldest CF in operation at the time of the first book. As the first excerpt shows, Grenzies are capable of rocket-assisted jumps but not hovering or sustained flight.

      That's the Grenzmark II's major advantage over the Grenzmark C.

    5. Aha. So we won't be seeing hovering or flying Grenzmark-Cs on earth, which is what I expected, seeing the thrust vs mass. Glad I'm interpreting things correctly. Hopefully you won't have to go through anything like Weber's Great Resizing: http://honorverse.wikia.com/wiki/Great_Resizing

    6. "So we won't be seeing hovering or flying Grenzmark-Cs on earth..."

      Correct. Grenzmark Cs are not flight-capable. Grenzmark IIs are. The logistics and much of the dramatic tension surrounding one particular mission in the book revolve around these facts.

  6. I have a question about a design choice on the Combat Frames, including (I think) the Grenzmark C--if you don't mind. Why are the forward-opening? I think that is how the samples describe them, since they jump from the cockpit to the knee... I would have expected a rear-facing door.

    1. They're forward-opening because a CF's back is almost completely covered with drive and maneuvering thrusters and weapon racks.

    2. Ah, cool! I figured there would be a good reason. By the way, the vampire story in Strange Matter (I don't know where my copy is, so I don't remember the story title) was Very Cool too. That one was worth the price of admission all on its own.

      I am very interested to see the XSeed story when it comes out. Do we have an estimated time to release I have missed, or is it still too early to say?

    3. The vampire story is titled "Izcacus". I'm delighted you enjoyed it.

      No estimated launch date for XSeed yet. I'm going for the Chris Fox/Nick Cole/Jason Anspach approach of having three books ready to go before I launch the first. I'm also waiting on art. I won't leave you hanging, though. Be on the lookout for a major event/announcement soon!

  7. Brian,

    Nice encyclopedia entry. This is a great beginning for tech manuals that the more model building oriented fans will appreciate.

    I look forward to ther osprey style uniform in colour plates and descriptions.


  8. This is _exactly_ the sort of material that would do well in collaboration with lore-focused YT channels such as Spacedock (for gearhead stuff) and Templin (for socio-political), and some videos done with them timed to come out shortly after you begin active promotion of the book would likely be beneficial.