Piloting rolls in atmosphere for GURPS TRAVELLER

hal · 06-02-2020, 07:13 AM

Hello folks,
I was curious - how many GM's or players have bothered with the Max Air Speed rules from GURPS VEHICLES and GURPS TRAVELLER?

Without saying what got me interested in investigating max speed for starships, I was wondering what happens when the speed is HIGHER for a space craft entering an atmosphere of any kind (whether a normal world atmosphere or a Gas Giant for wilderness refueling) than what the craft can handle.

My answer was found on the sidebar of GURPS VEHICLES page 164.

The gist of the answer is that the orbital speed of a planet is the speed required to get into orbit from the planet (not necessarily escape velocity, just what is needed to get into orbit). For Earth, the example was 17,800 mph.

So, let's say you have a starship with Fair streamlining (the first level of streamlining above none). That gives you a max airspeed of 600 miles per hour. Such a spacecraft, entering into Earth's atmosphere and attempting to aerobrake - would require (17,800 mph - 600 mph)/1,500 minutes to execute. This works out to 11.47 minutes. The rules state the ship takes 4 points of damage per minute, for each of the following Areas:

Underside of its body,
Its wings
Any subassembly under its body

1/4 of that applied damage is also applied to all other locations.

The fun part is this: Roll against Piloting - if the roll fails, the damage done is equal to the amount the skill roll failed by x the damage. So a pilot who fails his skill roll by 3, will inflict three times as much damage to his starship than had he succeeded. A critical failure will inflict 20x as much damage as a successful roll.

See sidebar pg 164 of GURPS VEHICLES 2nd edition for the full particulars.

What I intend to do is treat various "hull configuruations" in Traveller as being varying types of streamlining. Configuration Four for instance (See Classic Traveller) - will be treated as "Fair Streamlining" when I design ships for my campaign.

Just thought I'd share this with people.

06-02-2020, 07:13 AM	#1
hal Join Date: Aug 2004 Location: Buffalo, New York	Piloting rolls in atmosphere for GURPS TRAVELLER Hello folks, I was curious - how many GM's or players have bothered with the Max Air Speed rules from GURPS VEHICLES and GURPS TRAVELLER? Without saying what got me interested in investigating max speed for starships, I was wondering what happens when the speed is HIGHER for a space craft entering an atmosphere of any kind (whether a normal world atmosphere or a Gas Giant for wilderness refueling) than what the craft can handle. My answer was found on the sidebar of GURPS VEHICLES page 164. The gist of the answer is that the orbital speed of a planet is the speed required to get into orbit from the planet (not necessarily escape velocity, just what is needed to get into orbit). For Earth, the example was 17,800 mph. So, let's say you have a starship with Fair streamlining (the first level of streamlining above none). That gives you a max airspeed of 600 miles per hour. Such a spacecraft, entering into Earth's atmosphere and attempting to aerobrake - would require (17,800 mph - 600 mph)/1,500 minutes to execute. This works out to 11.47 minutes. The rules state the ship takes 4 points of damage per minute, for each of the following Areas: Underside of its body, Its wings Any subassembly under its body 1/4 of that applied damage is also applied to all other locations. The fun part is this: Roll against Piloting - if the roll fails, the damage done is equal to the amount the skill roll failed by x the damage. So a pilot who fails his skill roll by 3, will inflict three times as much damage to his starship than had he succeeded. A critical failure will inflict 20x as much damage as a successful roll. See sidebar pg 164 of GURPS VEHICLES 2nd edition for the full particulars. What I intend to do is treat various "hull configuruations" in Traveller as being varying types of streamlining. Configuration Four for instance (See Classic Traveller) - will be treated as "Fair Streamlining" when I design ships for my campaign. Just thought I'd share this with people.