One of the player’s stated goals for Knuer, the techie, is to own a jetpack. He’s an airship pilot, and he needs options for when the time comes to bail out from a burning balloon. Since I need to get comfortable with the GURPS Monster Hunters inventing rules, let’s run through some options.
The standard MH rules have a modifier for “every decade… from general consumption”, which starts racking up quick when you’re talking about a starting year of 1851, especially when folks want to be able to create TL 5+1 WWII-era guns or TL 5+3 difference engines. Therefore, I’m going to instead be using the standard -5 per TL modifier from GURPS Basic Set: Campaigns, page 475.
Let’s see if we can sneak up on this “jetpack” idea, since there might be easier, more steampunk-y options along the way. What we’re looking for, really, is some kind of man-portable emergency flight technology.
We could start with the TL 7 hang-glider from GURPS High Tech, page 232. The modified base cost for a folding TL 5+2 hang-glider would be $8,000, for a complexity modifier of -1. Knuer could roll Scrounging -1 to come up with the parts, or just pay $80 out of pocket. Then, with no more than a couple of hours’ work, he would roll Inventor! at -11, with success meaning accepting a bug in the prototype and a critical success meaning no bug. If he could make a Weird Science roll, he would roll Inventor! at -6, but might have to accept a strange side effect. (Of course, all of these rolls could be affected by spending wildcard points and so forth.) Once built, the prototype would only work for (1d + margin of success) minutes before being at risk of failure.
For comparison, let’s run through the Quick Gadgeteering rules from the Basic Set: A TL 7 hang glider, by price, is Average complexity. First, Knuer would need to make a concept roll, using Inventor! at -2. Assembling a prototype would require 1d-2 hours. Again, he could Scrounge for the parts, but at -2. Failing that, he could pay $6,000 for a facility suitable for inventing hang gliders, and $80 for the materials to build a prototype. He would need to roll Inventor! at -12, or -7 with Weird Science, to successfully build the prototype, but success by anything less than a margin of three would introduce bugs. Barring trouble from those bugs, the prototype would be as durable as any other piece of equipment. In time, he might be able to set up a production line to build hang gliders for sale to the public.
However, Knuer wants powered flight, so let’s run through the calculations using the ram-air parachute from HT, p. 232, a TL 8 gadget with a modifier cost of $28,000. Using MH rules, that’s no more than 3 hours of work, Scrounging -2 or pay $280, roll Inventor! at -17 or -9 with Weird Science.
The Basic Set rules say the ram-air parachute is still Average complexity, meaning the concept roll would still be at -2, and the facility cost would remain the same, but the cost per prototype would jump to $280. The roll to create the prototype would be at -17, or -9 with Weird Science.
Finally, what about a TL 9 helipack (GURPS Ultra-Tech, p. 231)? With a starting price of $320K, MH rules give a base time of 1d hours and a complexity modifier of -3, plus -20 in Tech Level modifiers. If Scrounging -3 doesn’t work, it’s $3,200 in parts. Roll Inventor! at -23, or -13 with Weird Science.
By the basic rules, the helipack is a Complex invention, with a base -4 modifier. The facility cost is $22,500 and each prototype will cost $3,200. The roll to create would be at -24, or -14 with Weird Science.
So: it seems that the MH rules are for field-expedient, “MacGyver-ed” creations. If you want an invention to last, you’ll need to invest in expensive production equipment. And, even spending wildcard points, given his 18- skill roll, Knuer is likely to use Weird Science and end up with an air-ram parachute… but coal-fueled, ghost-attracting, and whistling like a tea kettle.