Unlikely Collisions

It has come time for me to determine what happens when a DropShip crashes into a Mobile Structure.

For this adventure design, I'm going to work from the climax back.   First off, the point of impact.  The base rules for Ramming Attacks are in Total Warfare, p. 241.  I admit, I have rarely had to consult Total Warfare in this campaign, so it is nice to dust that book off.  The attack calls for pilot to make a steeling check (2D6 against a TN of 10), which I can likely handwave with roleplaying, especially since the plan calls for the pilot to bail out shortly before impact.  The actual attack role is a base TN of 6 modified by damage, target type, and attacker type.  Unfortunately, the rules in Total Warfare only talk about spacecraft ramming other spacecraft.  For spacecraft ramming a mobile structure, I need to flip open Strategic Operations to page 96, where there is the Expanded Ramming Attacks Table.

Here we learn that the modifier to hit a Mobile Structure is Variable (footnote).  Looking at the footnote, we find that Mobile Structures apply a -2 to every ten hexes (round up) the structure has.  Given the Wyrm is an 18-hex Mobile Structure, we get a -4 to hit it.  Of course, in order to actually split and sink the ship, the party needs to hit a relatively specific point on the Wyrm, but we'll get to that in a bit.

In Tactical Operations, page 168, there are rules for Mobile Structures ramming DropShips, but damage application in the other direction is less clear.  Attacks against Mobile Structures are done as per attacks against buildings, but again, there are no good rules for multihex DropShips crashing into multihex buildings.  So here's how I'm ruling this engagement.

There is a point attack -- the Aim Hex -- that the actual ramming attack is centered on.  I can calculate the amount of damage this attack will do if successful (the mass of the DropShip divided by ten, times the impact speed in aerohexes.)  Assuming the DropShip impacts nose-first, the damage it does will be divided by the impact profile (linearly to make the math easier), which for a small DropShip should be just about the width of the Wyrm.

The plan as filed calls for a Buccaneer-class DropShip (Technical Readout: 3057, page 26), although many different ships could work.  A Buccaneer has a mass of 3,500 tons, meaning it will do 350 damage per unit of velocity on impact.  It also has a beam of 127 meters and height of 30 meters, making its impact profile a row of hexes four long.  That means that the DropShip will do 87 damage to each of those hexes as it impacts per point of velocity.  Each Wyrm hex has 300 points of combined armor and construction factor, indicating that the DropShip will have to be underway at at least four velocity at the moment of impact to destroy the hexes it hits.  The DropShip has a Maximum Thrust of 5, meaning it is well within its capability to be traveling at that speed in atmosphere -- with the throttle winged open, it can maintain a flight speed of 10 in atmo.

There is one more complication, because this is running at the RPG-scale and we track such things.  A Buccaneer weighs 3,500 tons fully loaded.  If it is not fully loaded, its 2,308.5-ton cargo bay is at least partially empty, reducing the ship's mass to 1,191.5 tons, and its damage on impact to 119 points per velocity.  At this mass, the ship needs to be moving 11 hexes per turn, beyond its top speed, to do the damage it needs to do.

Now, all this presumes that the impact occurs on-target.  Being as this is a RPG roll, the attack roll will be the pilot's Piloting/Aerospace with a heap of modifiers.  The first will be -4 for hitting the enormous target.  The second will be +1 because they're flying a DropShip.  The next will be +4, since the terminal phase of the flight be be unmanned (the pilot expects to bail out just before impact.)  In addition, there may be damage modifiers if their intentions are detected ahead of time.   If the roll fails, the DropShip misses by MoF hexes, and almost certainly will fail to sink the Wyrm, and may well miss entirely.

Of course, before they can do that, the party needs to obtain this DropShip, which is almost an adventure in itself.  So very, very much that can go wrong with this plan.  Tune in Monday to hear how it turns out.