Tuesday, August 21, 2018

Hard Space - Spaceflight

How do you travel between planets in Hard Space? I've written about this subject before, in the previous iteration of Hard Space, but since then I have had some new ideas, especially following a very fruitful discussion on the Citizens of the Imperium forums. So here you go for spaceflight:

  • There are no gravitics in this setting. Not even as a side-effect of the Jump Drive. Neither are there reactionless drives. So there are no air/rafts - instead, you use a tilt-rotor, chopper, or ducted fan/vector-thrust. Or just a ground vehicle. You also must use reaction engines to travel in real space, mainly fusion torches. Which leads to the next point.
  • Interplanetary travel uses fusion torches. These require a fusion power plant, which uses regular Traveller p-plant stats. 10% of ship tonnage in propellant ("fuel") allows 100 thrust hours at 1-G*; faster travel requires a proportionally larger fuel tank. For example, 100 hours of constant 2-G acceleration would require 20% of ship tonnage in propellant.
  • Fusion torches are devastating and dangerous to use in atmospheres. Thus, the cost of streamlining subsumes interface engines, such as Scramjet engines coupled with vector-thrust jets for the final landing (or initial takeoff) itself. Most starships are not streamlined and use streamlined small craft.
  • Again, there are no gravitics in this setting. Stations spin. Ships have a "tower tail-sitter" structure with the engines below the "floor". This allows "gravity" by constant acceleration or deceleration. Ships in orbit either dock with a station, or stay in a powered orbit at 0.1g acceleration to maintain some shipboard "gravity". In long-term orbital "parking" without a station, this will require refueling from time to time.
  • There are no inertial dampers. This means that travellers must endure acceleration stress when accelerating beyond 1-G. Commercial ships, and even military ships in routine non-emergency travel, often stay at 1-G acceleration while travelling. For higher acceleration, crews and passengers buckle down and get a "cocktail" IV. The "cocktail" is a mixture of several medications allowing functioning and preventing stroke during high-G maneuvers, such as during combat or when travelling beyond 1-G acceleration.
  • Better starports provide their own interface craft for swift off-loading and loading of the visiting ship. Starports A's (Earth, Luna, and Mars) have "beanstalks" (space elevators) for massive transportation of material between surface and orbit. Starport B has a large "highport" space station and a fleet of heavy interface shuttles. Starport C has a small "highport" and a smaller fleet of interface shuttles. Starport D lacks orbital facilities but often has some interface shuttles available. Starport E rarely has any local infrastructure, though some colonies do keep local small-craft which may assist in offloading a coming trader.
  • Some smaller starships can land in atmospheres. However, the axis of a starship and that of a streamlined aircraft (or small craft) are different due to the above-mentioned gravity concerns and the ships being "tail-sitters". Starships capable of landing do so like rockets, with chemical (or plasma?) thrusters for both descent and ascent. A bit like the proposed (real-world) Phoenix Single-Stage-To-Orbit fully-reusable launcher/lander.

In the next post, I'll detail interstellar travel.

* Yes, I know this is grossly unrealistic in terms of engine efficiency, but its still a far smaller "handwave" than reactionless grav-drives, and it also prevents the "near-C rock" issue with gravitic thruster plates. Also using volume rather than mass for ships for Traveller legacy compatibility...


  1. What TL do you but mass produced 'Buckminster-fulleriena' at? Since such a material will change some aspects of construction. An Earth gravity bean stalk is proposed as possible.


    1. In my case, TL9; Earth indeed has a "beanstalk" in this setting.

  2. You might have a look at Paul Gazis's Eight Worlds:


    It does represent a significant overhaul of ships, but is also a no-gravitics system.


    1. Thanks for the link! I read it a while ago, but I will re-read it soon.