VCK Armor Rewrite

The armor component for the Vehicle Construction Kit needs rewriting.

Firstly, the “undersized penalty” for Armor Class is inconsistent with the “average AC” use for overall vehicle AC. One armor component should give the same overall AC as two one-step armor components, or three two-step undersized armor components, etc. So the undersized penalty is gone. Instead overall AC is the average AC of the best three slots, and a slot has the average AC of the components within it (using AC 11 for non-armor components.

Hopefully people won’t find this complex, unless you find division harder than subtraction. You can always ignore undersized armor completely.

Secondly, I’ve made the assumption that a vehicle’s armor also represents its reinforcing material. So, the reinforcement component is gone and armor now grants extra hit points. A vehicle’s base hit points is reduced accordingly, so you can have “fragile object” vehicles with no armor. Hit points are proportional to the cube-root of a vehicles mass, so you add up all the extra hit points of all the armor components and apply a multiplier (yes, table will be provided). Undersized armor can also be “armor plating” that has reduced hit points but retains its AC.

Thirdly, costs have been adjusted. Adamantine is now solid adamantine, not “adamantine-plated whatever”. It’s 6000 gp for a mass i component now (from 200 gp). You make your own “plating” by using an undersized component. That’s the point of more expensive armors: you can use less of it to achieve the same protection as a cheaper armor.

Now with three values – AC, Hit Points and Cost – armor can be more versatile. Bronze isn’t as hard as iron but is stronger and more expensive. Darkwood has twice the hit points of wood. Glass and ceramics are hard but brittle. You can create composite materials that average the values of its layers.

Behind The Curtain: Despite D&D being heavily abstracted, I’m not fond of just pulling numbers out of the air. I’ve tried to do a bit of research into real material properties. To my fault, I like to come up with formulas that convert real properties into D&D statistics.

An armor’s extra hit points is one-tenth of the material’s ultimate tensile strength (in MPa), since I reason that this is roughly the vehicle’s resilience to the various impacts it might take. This is 6 for wood and 18 for iron. Happily this seems to give about the correct total hit points for my test vehicles (rowboat, apparatus of kwalish, sailing ship and warship). I’ve set the upper limit, adamantine, at 90, the same as titanium: a 2-ton vehicle with full solid adamantine armor has 840 hit points but will cost a minimum of 18,000 gp. May need to reduce this? (to be fair, it would be a very rare magic item).

AC for metal is… wait for it… 12.5 + 3 times the common logarithm of the material’s hardness (in kilograms-force per square millimeter ) in the Vicker’s hardness test. This gives the following ACs: Lead (14), Silver/Gold (16), Bronze (18) and Iron (19).  At the very top of the scale, if diamond could magically be transmuted into armor plates, it would have an AC of 24. I don’t know about you, but I think that formula gives convincing results.



New VCK Supplement Catapulted to DMs Guild

The double-colon title had to happen at some point.

Vehicle Construction Kit Supplement 5: Artillery II: Catapults has now been uploaded to the Dungeon Master’s Guild.

The core Vehicle Construction Kit book has been updated, along with Tiny and Titanic, to reflect the changes in artillery.

This now leaves a few in-progress supplements:

  • “Magic” has been sat around for a year now as I’m not entirely sure what to keep in or take out. It currently includes a bunch more magic enhancements, some example vehicles adapted from Dragon magazine, a fairly versatile “spell machine” component (for creating lightning cannons or eldritch exhausts), an option for using a brain-in-a-jar instead of a pilot, and some rules for living vehicles and masterwork vehicles.
  • A “rules compendium” contain a selection of optional rules I took out of  Tiny and Titanic, since they didn’t fit the theme. Some of these look like they belong in a themed supplement. For example, autoloaders probably need to go in the eventual Artillery III (industrial and early modern)
  • “Castle Walls”. Artillery needs something to smash. I have some notes on how VCK can be used to make castle walls.
  • Something called “atomic power”?!

I need to decide what to finish next…

Supplement of a Supplement: VCK Catapults

Another Vehicle Construction Kit supplement is on the way. I need to rewrite the Artillery component section in the VCK to fit the new design laid out in the Artillery / Cannons supplement. But before I do that, I need to suss out exactly how the DMG siege engines (ballista, trebuchet, etc) fit the design.

The theme for the new supplement is “catapults”, which covers everything that throws something. It includes the counterweight trebuchet, traction trebuchet, hybrid trebuchet, ballista, siege crossbows (oxybeles, gastraphetes) and mangonel (here meaning a one-armed torsion-powered weapon – your classic “catapult” catapult, like an onager). All in light, medium and heavy variants!

The statistics are finalised, so I just need to write some descriptive text, alternate ammunition types, and probably an example vehicle (how about the helepolis?).

I’m also thinking of including different types of castle walls, as the VCK system can be used to work out their hit points, AC and damage threshold.

VCK Supplement 4: Artillery and Gun Artillery

It’s published!

The rather awkward title is because the book is in two parts: the first covers the reworked rules for artillery components, and the second part gives statistics for gun artillery.

Next, I need to rewrite the artillery component sections in the core VCK book and Tiny & Titanic so that it’s all consistent. Because the way weapon sizes have changed, warwolves and swivel cannons are being moved to T&T.

VCK Artillery Imminent!

I see the light at the end of the tunnel… and it’s a flash of gunpowder!

It feels like much longer than 2 months, but I’m putting the final touches on the Vehicle Construction Kit supplement that 1) overhauls the artillery component and 2) provides a nice variety of gun artillery.

I agonised over how to present something with a footing in reality while staying true to the information on siege engines in the Dungeon Master’s Guide. Is the “cannon” a field gun, or a battering gun? Is it a medieval bombard or a renaissance cannon? It only requires 3 crew, but deals an average of 44 damage?  That’s enough to overcome the damage resistance of all but the most immense vehicles.

I tweaked and tweaked and tweaked again. In the end, the way I have object size scaled to VCK “mass categories” means that a Large-sized cannon is about a 40-pounder, so the DMG “cannon” is indeed a battering gun for tackling castle walls and warships. But, the crew requirement goes up.. from 3 to 10! With one action per crewmember, this gives a rate of fire of once per minute, which is more-or-less correct.

I came up with a nice variety of gun statistics. For this supplement, I describe five types of gun:

  • medieval bombards (stone shot, large bore)
  • cannons (iron shot, medium range)
  • culverins (iron shot, long range).
  • perriers (stone shot, short range, effective against armour components)
  • mortars (indirect fire, explosive shot)

There are different sizes of each gun, from Small to Gargantuan. There are anti-infantry swivel cannons, and there are Mons Meg-sized siege bombards.

I also include an example vehicle based on the Mary Rose, an interesting carrack on the border between medieval and renaissance gun technology. It had a variety of guns, including old cast-iron bombards and newer, smaller bronze culverins.

Finalizing the supplement just involves adding a few images and uploading the PDF, which I will have to do this weekend. (My day job is working in a shop, and Black Friday is approaching…)

Vehicle Construction Kit and Artillery

It looks like the next VCK supplement will be some advanced rules for gunpowder-based artillery, as we deserve more options than just “cannon”. It’s not entirely clear what kind of cannon we’re dealing with, looking at the siege weapon in the Dungeon Master’s Guide, as it is deliberately abstract. It’s Large, it needs three crew, and it has a long range of 2,400 feet. What I don’t know: is this a medieval bombard, or is it an age-of-sail cannon? It doesn’t have the Renaissance tag introduced later in the DMG, and the range doesn’t compare with later cannons, so I suspect it’s a bombard.

The first thing then is to split my list of artillery into Medieval and Renaissance-era cannons.

The renaissance list isn’t hard to populate. There’s plenty of information about cannon weights, ammunition weights and how much gunpowder was used. I’m heavily relying on Albert Manucy’s Artillery through the Ages, with a few other sources. Numbers about ranges seems to vary, but in general a cannon has an “effective point blank” range which we can roughly take to be our long range. Angling a cannon can increase the maximum range for bombardments, which I’m making an optional rule: it’s used for battering fortifications but isn’t effective against creatures.

Medieval artillery is trickier, as there is less information. We know the weights of some famous bombards, such as Mons Meg or the great Turkish bombards, but I can find no information about how much gunpowder was used or what kind of ranges they had. There are some wonderful proto-cannons and rockets in the Huolongjing, and of course the Korean hwacha, but again no specific values. I’m going to have to…. make it up!

Vehicle Construction Kit 1.6.1 released

So there we go,

Other changes I made:

  • I slashed the cost of clockwork and battery power. Its unrealistically cheap now ( 200 lb-worth of mainsprings for only 60 gp), but I had to think about its game value. The only advantage they over other power systems is being non-magical and not requiring air to function.
  • Got rid of the “big attacks against small vehicles” rule, and instead allowed damage that destroys a component to disable adjacent components if it exceeds further multiples of the damage threshold.
  • Oh yes, renamed “damaged” components to “disabled” components. We already have the terms “damage” and “damage threshold” in use, and it’s just unnecessary overuse of the word.
  • Vertical propellers (the ones used just for Lift points), after some investigation, would have significant mass, so I made “lifting rotor” a type of rotary wing instead. I’ve balanced them so that muscle-powered lift is just possible so Da Vinci’s airscrew is possible. By the way have you seen the size of the rotors on real-life muscle-powered helicopters?
  • Muscle engines use “effort” instead of “push/pull weight”. Effort is simply the combined Strength scores of the operators, so there’s less calculation. Advanced muscle engine allows for a higher maximum effort. Why would you do that? The intention is that you can then undersize the muscle engine for the same Power Point output, until you get something like a modern bicycle system.
  • I’m not using Homebrewery for images anymore, because when I export the PDF, all the images become low resolution. I invested in a PDF editor to deal with this instead.

Next I am rewriting the Appendix B VCK examples to upload in a separate file. Large wagon didn’t need much change. Helical airscrew is rewritten with the new system described above.

The horseless carriage I changed into a Steam Wagon, inspired by Cugnot’s “Fardier à vapeur”, invented just on the cusp of the industrial revolution. I used the low pressure steam engine and simple wheel drivetrain. Pleasingly the vehicle’s speed comes out about the same as the real thing (2.5 mph while pulling a load of about the same weight as the vehicle). My version is a bit heavier at 6 tons.

The Steam Wagon had me thinking about how to handle pulled loads. Previously I had suggested making two profiles, for example with the steam train example, which is horrible. It just so happens that the steam wagon’s load is the same mass as the vehicle itself: if I had added a “cargo hold trailer” to slots 11-20 and mapped the vehicle down to slots 1-10, its Power Points would be halved. So that’s actually all we need to do: half the Points Points. We don’t need to do anything with the slots (optionally make a separate profile for the trailer alone, to get its hit points etc.)

I’ll be using this approach with my rewrite of the steam train. If it’s pulling two sets of carriages with equal mass, I just divide the Power Points by 3 to calculate its performance.