[Spaceships 7] Homebrew: Expanding on Gasbags

[Flyndaran]

A very weird omission, I agree. I think way back when I wanted to create a steam punk-ish dirigible, I had to use Vehicles from 3rd ed. to get something usable numbers. I know I created a thread asking about it, but can't remember specifics.

[DaltonS]

Originally Posted by Flyndaran

A very weird omission, I agree. I think way back when I wanted to create a steam punk-ish dirigible, I had to use Vehicles from 3rd ed. to get something usable numbers. I know I created a thread asking about it, but can't remember specifics.

I checked out that thread. A lot of interesting points were raised, but as this was a TL5 Dirigible they didn't seem directly applicable to this situation, although using my lift equations for your hydrogen gasbags could reduce their number and leave space for more systems. As for aerial propeller systems, I'm thinking the best design would be as dedicated power plants that provide thrust instead of power points. (Yes, that would be one for each type of power plant. ;) ) Figuring out just how much thrust is the tricky part. When I was translating Gravity Screens from GURPS Vehicles Expansion 2, the size of a standard energy point I used came from here.

Originally Posted by Anthony

We can derive it from two sources: power output of weapons, and power output of electric drives.
...
Overall, I'd assume 1 ep is somewhere around 100 kW/ton, which is on a par with a reasonable performance ground car (though said car probably isn't spending only 5% of its mass on its power plant).

I worked out the following figures from The "Airscrew Table" on VE2 p.33. With the airscrew having a mass of 2-3% of the power plant, I think it's safe to ignore it. The "Additional Cost" is per ton of system; add it to the cost of the power plant used.

                          Accel. Additional
TL      Type             (in Gs)  Cost/ton
5-6     Aerial Propeller  0.00625   $300
Late 6  Aerial Propeller  0.0075    $200
7+      Aerial Propeller  0.00875   $800
7       Ducted Fan        0.01     $2,400
8+      Ducted Fan        0.01     $1,600

What the 3E TLs translate to in 4E is problematical, as is top airspeed (500 mph for regular streamlined aircraft, 150 for dirigibles?).

Dalton “who wonders why he didn't work this out before” Spence