Mjölnir class fire support vessel

Xerxeskingofking · Aug 3, 2018

well, here is my latest little project. I'd been mulling over the idea of a conversion to a standard type R sub merchant, but ended up creating a ship that is effectively completely different, with only a passing resemblance to the fat trader, mechanically at least (I imagined that the ship looks very similar to the type R, but I have not the art skills to draw it, or really to deckplans for it).

Ship was created using MgT2e rules. any comments, feedback glaring errors spotted would be most welcome:

Spoiler:

Xerxeskingofking · Aug 3, 2018

background for the class, because I like writing background. again, comments and critiques are welcome.

Spoiler:

The Mjölnir class is a fire support vessel, designed to sit in low orbit over a planet and provide direct fire support to ground forces in the form of kinetic energy strikes from its mass driver.

In the early days of the 3rd Imperium, fire support for Imperial Marine and Army units was provided by whatever spacecraft the Navy could scrounge together.As things stabilised and the Imperium got its feet under it, Navy battleships and cruisers would carry one or two mass driver bays for this purpose, in addition to specialised space to surface bombardment missiles, allowing the Naval command to assign any capital ship to support a landing with high degree of effectiveness (The tradition of carrying large Marine contingents on navy ships also came about from this policy). However, this meant that these ships were then tied to that system in the fire support role until the ground campaign was won, which wasn't an issue against the smaller pocket empires, who rarely posed a naval threat after the first few battles, This became a problem when fighting larger states, where the navy was reluctant to leave major ships stuck in orbit when the enemy still had significant fleet assets, but generally the system worked up until the Imperial Civil War.

In the chaos and infighting of the Civil War, the system totally broke down. The war involved dozens of systems changing hand in rapid succession, often several times, and it was simply impossible to leave capital ships behind to in the rear while advancing towards the critical naval battle for Capital. Several attempted marches on the throne ground to a halt because of partisan activity on occupied planets stopping the logistical supply network form supporting the advance. Clearly, a new approach had to be found, and several options were tried. The most popular solution was called several names at the time, but generally became known as the fire support vessel (after the term used by Admiral Arbellatra’s forces in the Second Frontier War and subsequent march on Captial). The earliest examples of these were conversions of civilian free traders, where a mass driver or missle bay was installed into the cargo bay, often literally bolted onto place, which were then parked in orbit over troublesome worlds, freeing up naval warships for fighting elsewhere. Conversions of the type R Subsidised Merchant proved very popular with ground troops, as the “fat trader” was big enough to mount the more powerful 100 ton bays, while still small and cheap enough to be affordable in larger number, As the war progressed and any armed ship started looking tempting to any admiral wishing to bolster his fleet a little, there grew a preference in the Marine Corps for the mass diver-armed support ships, as missle bay equipped ships were more likely to get “retasked” by the navy.

By the end of the Civil War, purpose built fire support vessels were being built, and have remained in server every since. The Mjölnir class dates form this time, and while purpose built, the design take many cues form the type R refits it is based on, and shares the basic hull shape and layout. The mass driver is mounted in the front portion of the lower deck, and the three turrets are arranged in a triangle around the hull, positioned to give maximum fire forwards. The turrets are primarily intended for anti missile defence, but can be used to make precision strikes on ground targets where a mass driver impact would be too….messy.
The small craft hanger is also a holdover form the Type R roots, as the gigs were always in high demand by ground troops for tasks such as cas-evac, resupply, and extraction. The gig also came in handy for customs checks and other orbital work, and a fire-team of marines/naval infantry is kept on the ship for boarding actions or landing site security. The Underway Replenishment System allowed the class to be supplied by almost any light trader without assistance, which simplifies logistics and allows quick resupplies. The class only carries 13 rounds for the mass driver, but in a normal orbital it can only fire two or at most three rounds at a single point on the planet, so this is less of a issue.

The normal operational pattern is to deploy the ship in squadrons of 10-15, where they enter a low, fast orbit that minimises round travel time (and thus increases accuracy). The ships space out along the orbit so that any give point along the orbit is in clear view and line of fire of at least one ship. When firing, the ships “stand on the noses” and orient themselves bow on to the target, to give the best arc of fire and minimise the ships profile for return fire. The impact of a mass driver round at full velocity has been likened to a tactical nuclear strike, without the radioactive fallout, and very few targets can survive a direct hit, which is quite capable of breaking a armoured starship in two if it hits one.

While the design traces is direct ancestry back to the Imperial Civil War the jury rigged stop-gaps used in that conflict, but the basic idea stretches back to the dawn of space travel. Historical accounts of the Interstellar Wars contain references to ships that filled the same role, using similar mass driver technology, which the Terran Confederation ground troops nicknamed “Rods from God”, and the Vlani called it “Lighting on-call”. Imperial Marines often refer to mass driver strikes as “Dropping the hammer”, which while an unofficial term, likely influenced the choice of name for the class.

AnotherDilbert · Aug 3, 2018

I believe you have missed a few tons, I only get 12 Dton left for cargo.

Your PP fuel is slightly off, it should always be rounded up, so 2 Dt. It changes total endurance.

You could save a bit of space and money with tech advantages for the drives, as you already have with the bay.

I would suggest including fuel purifiers and radiation shielding, and perhaps Repair Drones and Signal Processing on a military ship.

Why beam lasers? Pulse lasers are better and only slightly more expensive.

Your crew level is a bit unorthodox? It is neither military nor civilian. In general we can round down. The bay should have two gunners.

Spoiler:

robject · Aug 4, 2018

Pardon my impudence, but it sounds like an awesome name (and even ship type) for the Sword Worlds.

I mean, look at it. TL 11. Jump 2. Fire support.

Oh yeah, I can imagine the adventures players could have on it.

Referee: Your Mid-bulk Trader docks with the derelict. Your vacc-suit propulsion units will carry you to the outer airlock, no problems. Sniffer readings are negligible - the ship has been exposed to vacuum long enough to leave no trace of interior atmosphere.

Mal [SEE FOOTNOTE]: Alright, folks, this is a quick recon. No fooling around - something shoots, you shoot back and retreat. No last stands here.

Zoe: Aye, captain, no desire to be riddled with gunfire, myself.

Kaylee: What? Who's getting riddled with gunfire this time?

Simon: Sounds like a toss-up between the captain... and Jayne.

Mal: Noone, that's who! You stay with the engines, and have 'em ready, just in case. And you... same thing for the infirmary. Just in case. Not that it'll be needed.

Simon: Uh huh.

Jayne: Awww... just a little shootin'... fixes all sorts 'a problems... [audience hears the sound of an ACR magazine snicking into the stock].

Mal: ...and no grenades.

Jayne: Awwww!

Book: Looks like a Mjölnir-class gunship. Sword Worlder fire support vessel. Quite capable. Anything can do that to a gunship, doesn't need to be tangled with.

Mal: Just my thinkin'. A quick look around, is all.

Book and Inara exchange glances.

River: Mjölnir... Thor's Hammer...

Wash (A short while time later): Not that anyone cares, but I'll be here on the bridge, you know... just in case.

FOOTNOTE: If you prefer not to violate copyrights, substitute: Mat for Mal, Zane for Zoe (F->M), Katie for Kaylee, Esteban for Simon, Leslie for Jayne, Preacher for Book, Erin for Inara, Savannah for River, and Wendy for Wash (M->F).

Xerxeskingofking · Aug 5, 2018

robject said:
Pardon my impudence, but it sounds like an awesome name (and even ship type) for the Sword Worlds.

I mean, look at it. TL 11. Jump 2. Fire support.

Oh yeah, I can imagine the adventures players could have on it.

TL12. the P-plant is the TL12 type at 15PP per ton, and she has 12 points of hull armour (which makes it a TL12 hull). But yhea, it would work nicely at adventure scale. Your welcome to fix it, play with it and use it in your games. Like I said, I don't have the artistic talent to knock out deck plans, but its basically the same floorplan as a Type R, with the bay in the front of the cargo deck, ammo behind, and then the expanded engine rooms at the rear of the cargo deck, with the extra fuel on the passenger deck in place of the rear staterooms. I havnt actually worked out if that is viable in terms of space, but that was my plan.

the name basically came about because I'd already settled on the imps calling the mass driver strikes "dropping the hammer", so I was left thinking of hammer related names for the class, and Mjolnir is just so obvious, as well as well known enough I didn't feel I had to explain the name.

if you wanted a more space combat design, you could swap the mass driver bay with something else, like a missile bay or a railgun bay, but shes a touch slow for combat.

I believe you have missed a few tons, I only get 12 Dton left for cargo.

Your PP fuel is slightly off, it should always be rounded up, so 2 Dt. It changes total endurance.

You could save a bit of space and money with tech advantages for the drives, as you already have with the bay.

I would suggest including fuel purifiers and radiation shielding, and perhaps Repair Drones and Signal Processing on a military ship.

Why beam lasers? Pulse lasers are better and only slightly more expensive.

Your crew level is a bit unorthodox? It is neither military nor civilian. In general we can round down. The bay should have two gunners.

I very likely missed a few tons, I was tinkering with it late at night and likely got my sums wrong. half my reason for posting was to use you guys to proof read my work, so thankyou.

Fuel purifiers were an oversight, will need to add those back into the design.

I missed the "rounding up" tag on that PP fuel, so I will correct that.

I'm trying to keep the TL down to 12, so that puts a hard cap on how many tech shrinking I can use. 2g is TL10, and J2 is TL11. I can save, at most, 3 tons (2 tons form the J drive, and 1 ton off the M drive), for the cost of about 7Mcr, which is a pretty big price increase for a fairly small amount of extra room.

main reason for Beam lasers is the +4 to hit bonus they get (core rules, pg156, "common modifiers to Spacecraft attacks"). the turrets are intended for point defense or precison attacks on ground targets, so a high accuracy is more important that high damage.

Yhea, the crew level is a bit of a mess. its wasn't possible to mount a full military crew on the ship, at least no without dropping the bay down to a 50 tonner (which might be a better way to go about this anyway. That, or remove the extra ammo and just keep the 6 rounds in the bay).

sod it, I was dead set on trying to squeeze a 100 ton bay in, but it looks like It is really too much for a armoured jump ship at this size. better to either make it boat (would save about 100 tons, between the jump fuel and j drive), or step the bay down to a 50 tonner, and use the extra tonnage freed up for more crew and cargo space, as I wasn't really happy with only 12 tons storage. I take this back to the drawing board and re-work it a bit, most likely taking the 50 ton bay route.

Matt123 · Aug 5, 2018

Just for the fun, a CT version. It's a good design

I'm picking the Ships Troops man the Mass Driver, I've added a team leader who might double up as a Forward Observer in the Cutter. In CT I've assumed the Mass Driver is fitted as cargo and the Ships Troops/Marines fire it out the open cargo bay doors (or similar). Not sure about the ship's computer size in MgT rules, this one has the minimum needed to support J2.

Also made it TL11. In CT a TL12 version gets Armour 6 or 7 which I didn't feel was enough of a boost to warrant TL12 production. In any case something like this should be escorted by Close Escort or similar.

Xerses Mjolnir Fire Support, Strike Barge
400 ton, TL 11 Military Design, 241.53 MCr
9 crew plus 5 Marines (Command: 1+1, Engineers: 1+1, Flight: 0+1, Gunners: 1+2, Marines: 1+4, Medic: 0+1)
no passengers

__Ton.____MCr.__EP.____
| ___.__ | _32.00 | _.__ | Flattened Sphere, streamlined, fuel scoops
| _60.00 | _42.00 | _.__ | hull armour #4
| __7.00 | __0.03 | _.__ | purification plant
| _20.00 | __2.00 | _.__ | bridge
| __2.00 | __9.00 | _.__ | computer model 2
| _12.00 | _48.00 | _.__ | drive jump #2
| _20.00 | _14.00 | _.__ | drive maneouver #2
| _27.00 | _81.00 | _.__ | power plant #2
| __9.00 | ___.__ | _.__ | fuel, PP endurance 4 weeks (9 weeks powered down)
| _80.00 | ___.__ | _.__ | fuel, jump range 2 parsecs
| __3.00 | __9.00 | 9.00 | beam lasers (turret) #3 x3
| _16.00 | __2.00 | _.__ | staterooms x4
| _20.00 | __2.50 | _.__ | cabins x10
| 104.00 | ___.__ | _.__ | 104 ton reserved weapon space in cargo bay
| _20.00 | ___.__ | _.__ | hanger space for 20 ton Launch
‒‒‒‒‒‒‒‒‒‒‒‒‒‒‒‒‒‒‒‒‒‒‒‒‒‒
| 400.00 | 241.53 | 9.00 EP used, PP generates 9.00 EPs

243.95 MCr (first ship, includes architect fees) built in 64 weeks
193.23 MCr (20% discount in volume, TCS) built in 52 weeks
CT Ship Designer by Matt. Visit https://tca-2014-12.herokuapp.com

Xerxeskingofking · Aug 5, 2018

cool. I was under the impression that CT ships under 1,000 Dtons could not mount bay weapons?

There is no tonnage required for MgT computers, they are assumed to be spread about thoughtout the ship and subsumed into the tonnage of the bridge, engines, weapons, Staterooms, etc.

AnotherDilbert · Aug 5, 2018

Xerxeskingofking said:
I'm trying to keep the TL down to 12, so that puts a hard cap on how many tech shrinking I can use. 2g is TL10, and J2 is TL11. I can save, at most, 3 tons (2 tons form the J drive, and 1 ton off the M drive), for the cost of about 7Mcr, which is a pretty big price increase for a fairly small amount of extra room.

I believe the cost is calculated based on actual size of drives, not nominal size. So the higher cost per ton would be based on the reduced size, hence not much more expensive.

You can use a size-reduced TL-8 power plant, it will be roughly the same size as a basic TL12 plant, but cheaper.

I get size-reduced TL12 drives to this:

Not a big difference from basic drives, but it does save you a few tons and MCrs...

Xerxeskingofking said:
main reason for Beam lasers is the +4 to hit bonus they get (core rules, pg156, "common modifiers to Spacecraft attacks"). the turrets are intended for point defense or precison attacks on ground targets, so a high accuracy is more important that high damage.

I don't think lasers get their attack DM on point defence, since that is technically not an attack.

Point taken on ground attacks.

Xerxeskingofking said:
Yhea, the crew level is a bit of a mess. its wasn't possible to mount a full military crew on the ship, at least no without dropping the bay down to a 50 tonner (which might be a better way to go about this anyway. That, or remove the extra ammo and just keep the 6 rounds in the bay).

I wouldn't reduce ammo, that would just mean we would need another ship as ammo tender.

Xerxeskingofking said:
sod it, I was dead set on trying to squeeze a 100 ton bay in, but it looks like It is really too much for a armoured jump ship at this size. better to either make it boat (would save about 100 tons, between the jump fuel and j drive), or step the bay down to a 50 tonner, and use the extra tonnage freed up for more crew and cargo space, as I wasn't really happy with only 12 tons storage. I take this back to the drawing board and re-work it a bit, most likely taking the 50 ton bay route.

I would consider a boat, or perhaps cutting the drives to J-1 if you want to keep the militarised Subbie feel.

I'm assuming this craft will be intended to support fairly large ground formations, something like a brigade or division, and not operate independently? In such case we have already transported tens of thousands of tons of personnel and equipment to the target system and a thousand tons extra to transport a few ortillery platforms wouldn't be much of a problem.

With J-1 performance it would need to be transported to the general area of operations, but could then move itself within the system and neighbouring systems, and could retreat from superior naval forces.

How about something like this:

Standard Subbie drives, for ease of maintenance, with a little bigger PP. By keeping the PP exactly 10 Dt we minimise the PP fuel need and maximise the endurance.
Standard Subbie crew and passenger compartment (half the deck plan already done). Space for a full military crew, and with double occupancy perhaps an extra squad as a quick reaction force.
Leaving space for the medium bay, ammo, and 34 Dt cargo.

The power budget is strained, we have to choose between acceleration and constraining basic systems in combat, but I think that is acceptable for an ortillery ship.

Ulsyus · Aug 5, 2018

Why are there four ships troops on something that small? If it's a dedicated fire-support vessel, it certainly wouldn't be jumping about on its own, it'd be part of a task force and so able to rely on the security offered by being part of a formation, transit and rear-movements notwithstanding, and speaking from a purely practical perspective that is.

Also, this might be a IMTU thing, but I allow mass-drivers to fire smaller calibre rounds to be fired using a sabot, so there's not the same need to rely on the lasers for less-than-maximum effect from the main weapon. That could also be useful for putting down supporting fire for troops who couldn't get it from the ground if engaged in a three block war.

Matt123 · Aug 6, 2018

Xerxeskingofking said:
cool. I was under the impression that CT ships under 1,000 Dtons could not mount bay weapons?

You are right, but in this case I would fudge it as not being a ships weapon as such. I have treated it here as cargo, cargo that can be operated by the ships troops independently from the ship. Provided the cargo bay door is open and assuming the Captain is prepared to cooperate in placing the ship in orbit, facing arse down over the target area.

Ulsyus, there are no ships crew allocated to manning it. I stuck with the ships troops theme as I like the idea it is Marine equipment likely loaded as cargo and needing Marine crew.

Xerxeskingofking · Aug 6, 2018

Ulsyus said:
Why are there four ships troops on something that small? If it's a dedicated fire-support vessel, it certainly wouldn't be jumping about on its own, it'd be part of a task force and so able to rely on the security offered by being part of a formation, transit and rear-movements notwithstanding, and speaking from a purely practical perspective that is.

part of my original idea for the class was that it could be left in orbit over a occupied world while the main fleet moves on to other tasks, so it might be one of only a few navy ships in orbit around a given world.

another reason for the troops was to protect the Gig if was required to make a landing in a "hot" LZ (for example, for casualty extraction), like how medievac helicopters carry a few grunts to cover the medical staff.

also, navy ships tend to get dragged into covering a number of different jobs, so being able to act as a customs picket (with a small craft and suitably trained boarding team) would be a valuable feature for a small navy vessel.

Mjölnir class fire support vessel

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