Ultra-Tech: Vortex Ring Projector Design System

Ultra-Tech: Vortex Ring Projector Design System

One of my friends is planning to host a sci-fi game, so he asked me to write something about vortex ring

projectors. VRPs don't seem very popular, even Google only links to two threads on the SJGames forums. However, the concept fascinated me. I treid looking into 3e Ultra-Tech books, but found nothing. Apparently, VRPs appeared in the fourth edition. Then, before creating some fun superscience gases for the VRPs, I decided to write up a design system based on the Blaster and Laser Design System from Pyramid #3-37 - Tech and Toys II. Many formulas and values were changed to fit the VRPs. It's not a blaster, not a laser after all.

I use the post template of TheRyujinLP. Check out his blog for some extra beam/laser design options.

Use the algorithm from the aforementioned article, but with the following changes.

Beam

Vortex Ring Projector (TL9): These advanced gas projector weapons consist of a reservoir tank, a chamber for mixing the delivery gas with a propellant, and a wave-shaping chamber that forms the ejected cloud into a vortex ring – a high-velocity smoke ring. See more details on page 134 of GURPS Ultra-Tech.

Example: Let's design a relatively long range vortex ring rifle.

Focal Array

Obviously, vortex ring projectors lack focal arrays, because they are not beams. Instead, let's use Barrel Length instead. Honestly, I am no physicist and I do not know the mechanism of vortex ring formation, but let's assume that the longer the barrel is, the further the ring can travel. However, the effects of the Barrel Length will be different in the aspect of numbers.

Example: We choose Very Large. Longer barrels probably should be used for cannons and such.

Generator

Vortex ring projectors can only take the Single Shot option. GURPS lacks rules for cones and area effects with RoF 1+, forbids this combination for advantages, but still has them on some sonic weaponry in GURPS Ultra-Tech. How do they work? Nobody really knows.

Damage

Vortex ring projectors disperse a gas in an area after the ring hits a solid object and have a linked 1d-3 cr dkb effect. For the purpose of calculation, treat each 1 yard of the disperal radius as 5 dice of damage. For small vortex rings that have to hit the face to affect the target have 2 dice of damage. VRP pistols shouldn't have an area of more than 1 yard. Reserve areas with a 2-yard radius for rifles and more heavy weaponry. Honestly, I am not sure if larger areas are even physically possible, and I haven't even ran any numbers for them.

Example: We want a 1-yard radius here, so D is 5d.

Empty Weight

E = 4,6.

Example: Empty Weight = (5/4,6)^3 x 1.6 = 2 lbs. This is a quite light weapon.

Accuracy

Accuracy Table

Beam	Beamer	Pistol	Rifle	Cannon
Vortex ring projector	1	2	3	3

Example: Vortex ring rifle is, well, a rifle, so it's Acc is 3.

Range

Vortex ring projectors have no 1/2D range (I assume that the 20/40 in the underbarrel vortex projector is a typo, and the actual number is 20). I may be mistaken, but it feels to me that larger rings should travel shorter distances, so I tried to take that in account. Range is calculated differently, using the following formula: Range = RFx60/D^(1/2).

where RF depends on Barrel Length: 0.25 for Tiny, 0.33 for Very Small; 0.57 for Small; 0.75 for Medium; 1.6 for Large; 2 for Very Large; and 2.4 for Extremely Large.

Example: Range = 2 x 60 / sqrt(5) = 53 yards. Let's round it up to 55 yards.

Shots

Now here's an interesting one. Vortex ring projector use gases, but there's no information on how many doses does each shot require. However, biochemical aerosol warhead (GURPS Ultra-Tech, p. 153) gives some values of gas doses per yard of area radius. Let's use these. Thus, for a small ring that must hit the face, each Shot equals to 1 dose. A 1-yard-radius Shot equals to 3 doses, and a 2-yard-radius Shot equals to 10 doses. I came up with the following formula to determine the weight of the gas reservoir for the vortex ring projectors: ResW = (Shots x Doses per Shot)^1.5/90 + (Shots x Doses per Shot)/100.

Example: We want the rifle's reservoir to contain 20 Shots. For 1-yard area DpS is 3. Thus, ResW = 5.76 lbs. Let's round it up to 5.8 lbs.

Reloading Time

Let's have it at 3 seconds for ResW of 1 lb or less, and 5 seconds for higher weights.

Example: ResW is higher than 1 lb, so reloading time is 5 seconds.

Weight

Weight = Empty Weight + ResW.

Example: Weight = 2 + 5.8 = 7.8 lbs. Looks fine for a rifle. ST requirements and Bulk are calculated using the formulas from the article.

Cost

Bc = $100.

Example: Cost = 2 x $100 = $200. Cheap.

Legality Class

Base LC for vortex ring projectors is 4.

And now we have a fully statted vortex ring rifle!

LIQUID PROJECTOR (SPRAYER) (Defaults to DX-4)

TL

Weapon

Damage

Acc

Range

Weight

RoF

Shots

ST

Bulk

Rcl

Cost

LC

9

Vortex Ring Rifle

spec. (1 yard)

3

55

7.8/5.8

1

20(5)

6†

-3

1

$200

3

linked

1d-3 cr dkb

I've ran some number tests, and the results line up quite neatly for the vortex pistol (small barrel length) and the backpack vortex projector (long barrel length). The underbarrel vortex projector's (medium barel length) weight ends up being lower, but it seems to me that 5 pounds is a bit overweight, so I'm fine with that.

New Gases and Clouds

The following new gases can be used not only with vortex ring projectors, but also with biochemical aerosol warheads and other sprayers.

Cryomist (TL9^)

This gas consists of tiny particles that drain the surrounding heat and freeze water vapors in the air, that manifests as a sheet of ice on hard surfaces and thin ice shells on living creatures. Cryomist deals 1d fatigue damage with the Freezing modifier per second to creatures without Sealed. In addition, it has a linked Binding effect. The Binding effect that has a ST equal to 6. The binding attack has HP equal to the binding effects ST and DR 2. Each additional second spent in the mist creates a new layer of ice. Each new layer increases the HP and DR by the same amount and increases the binding effects ST by 1. Ground in the mist becomes extremely slippery. All DX-based activities, including attack and defense rolls, are at ‑2 in the icy area. In addition, those moving into or through the area must roll against DX‑2 every turn or fall; this roll is at +1 if walking at Move/2, +2 at Move/4, and +3 at Move/8 (round down, minimum 0). Critical failure causes 1d‑2 injury to a randomly chosen limb. Anyone with Perfect Balance or Terrain Adaptation (Ice) may ignore the effects of this spell. $5 per dose. LC3.

Gravigas (TL10^)

This gas contains exotic particles that produce exert gravitational forces. Instead of its normal effect, the vortex ring deals 3d cr dkb damage per yard of radius. Small vortex rings that typically target the face are treated as having a radius of 0.5 yards for this purpose. Thus, a small vortex ring will deal 1d+2 cr dkb; a 1-yard vortex ring will dead 3d cr dkb; and a 2-yard vortext ring will deal 6d cr dkb. Add +1 per die per TL after 10. $15 per dose. LC3.

Thermobaric Gas (TL9^) (based on this forum post)

This gas contains particles of powdered sodium that ignites upon contact with water vapor. Within the vortex, it cannot interact with the atmosphere, so it only ignites upon striking the target or at the end of the range. Damage becomes 2.5d cr ex inc per yard of radius. Small vortex rings that typically target the face are treated as having a radius of 0.5 yards for this purpose. Thus, a small vortex ring will deal 1d+1 cr ex inc; a 1-yard vortex ring will dead 2d+2 cr ex inc; and a 2-yard vortext ring will deal 5d cr ex inc. Add +1 per die per TL after 9. $20 per dose. LC1.