Hard SF Mechanics

[mikeanthonywild]

This is a slightly odd request, but I'm hoping that maybe some of the kind folks here would be able to help me out.

I'm currently in the process of writing a hard SF game. While monkeying away on the core engine, I'm trying to sketch out a rough idea of how the game will work - ie. the mechanics.

One such problem is how to handle the propulsion systems. Theoretically, a ship could carry on accelerating to an almost infinite speed until it got closer to the speed of light (which would take a long time). The time taken obviously depends on the maximum acceleration limited by either what the human body can withstand, or what the structure can withstand (in the case of something like a sleeper ship).

That's all well and good, but in combat you don't want the throttles linked directly to the overall thrust. Ie. 100% throttle should not produce 100% thrust as you'd have ships going at wildly different speeds making combat a nightmare, not to mention try to pull off evasive maneuvers would be almost impossible.

For long distance travel you obviously want it so that the throttle is directly linked to thrust and thus controlling the rate of acceleration. For anything else you want it so that the throttle sets an absolute velocity up to a certain maximum velocity. How do I decide this maximum velocity?

I'm thinking something along the lines of:
We know the maximum deceleration (the lowest of: what the body can withstand, what the structure can withstand, or what the thruster can produce), thus if the ship travels at maximum 'combat' velocity and full reverse thrust is applied, the ship must come to a stop within X period of time.


I actually had another question too, but you will be pleased to hear that I've forgotten it haha!


Anywho, if you've read this far, thank you - I do have the tendency to waffle sometimes.

Thanks all,
Mike

[psikeyhackr]

Why not have a velocity control instead of an acceleration control and have computers do the necessary calculations to manage thrust. Let the pilot switch between velocity and acceleration controls. maybe have two separate w=controls to avoid pilot error and does not forget which he is using.

Check out The Antares Trilogy by Michael McCollum

psik

[noori noori]

one of my favorite ideas [its Sf related ..] is: ... teleportating Saucers ! ... just, if u had a means of just mentioning teleporting of your ship in your game u could circumvent your present idea; acceleration/deceleration. it could still-be a Core engine could nt it. still reasonably Hard

[mikeanthonywild]

That's a good idea, perhaps a switch somewhere to swap between modes, that way you can get away with only a single throttle control.

My main problem though is that the velocities in "velocity" mode are far smaller than those in "acceleration" mode - how do I decide what is an acceptable maximum velocity in the former case?

[mikeanthonywild]

one of my favorite ideas [its Sf related ..] is: ... teleportating Saucers ! ... just, if u had a means of just mentioning teleporting of your ship in your book u could circumvent your present idea; acceleration/deceleration. it could still-be a Core engine could nt it. still reasonably Hard

Sorry, you must have replied while I was typing. I didn't explain my self very well. 'Core engine' is game terminology. Unfortunately I don't think that teleportation fits in with my idea of hard science (that's my personal opinion though) and acceleration / deceleration seems more of a challenge to me

[noori noori]

Sorry, you must have replied while I was typing. I didn't explain my self very well. 'Core engine' is game terminology. Unfortunately I don't think that teleportation fits in with my idea of hard science (that's my personal opinion though) and acceleration / deceleration seems more of a challenge to me

sweet. i can see where u may be coming-from

[psikeyhackr]

That's a good idea, perhaps a switch somewhere to swap between modes, that way you can get away with only a single throttle control.

My main problem though is that the velocities in "velocity" mode are far smaller than those in "acceleration" mode - how do I decide what is an acceptable maximum velocity in the former case?

Your maximum velocity is going to be determined largely by your fuel consumption. What is the thrust to mass ratio for the fuel. Are you talking about entirely intra-solar system flight? Assuming you have to accelerate and decelerate at both ends of the trip the faster you go the more fuel you use up. If you accelerate to such a high velocity that you don't have enough fuel to slow down at your destination then you have a problem.

Or like in the movie 2010 they used Jupiter's atmosphere for atmospheric braking.

http://www.braeunig.us/space/propuls.htm

You may need to play around with the numbers for ship mass, fuel mass and ejection velocity. Are you talking about chemical rockets or an ion drive. Since this is science fiction you can just make up a power source to give yourself a great ion drive. Or suppose you had a fantastic but not too big and heavy power source and you could use lasers to vaporize iron and magnetically accelerate it to 10% of light speed. But how much detail do you want to go into this stuff. Maybe you just want your figures in the ballpark so the story does not seem unrealistic but not make exact calculations that only anal retentive pedants will check.

psik

[Werthead]

Have you played Frontier and First Encounters, the sequels to Elite? They used realistic (i.e. Newtonian) physics in the flight engine and it was interestingly implemanted. Though combat was somewhat difficult (as it would be in reality) with the ships trying to match speeds and vectors, firing off missiles etc.

[Omphalos]

Or like in the movie 2010 they used Jupiter's atmosphere for atmospheric braking.

Been a while since I saw/read 2010, but IIRC they used Jupiter to slingshot away from the planet. Am I remembering that wrong?

[Werthead]

Been a while since I saw/read 2010, but IIRC they used Jupiter to slingshot away from the planet. Am I remembering that wrong?

Near the start of the story, the Leonov uses Jupiter's atmosphere to aerobrake into orbit to rendezvous with Discovery. Later on Leonov uses Discovery as a rocket booster to help blast them away from the planet.

[psikeyhackr]

Been a while since I saw/read 2010, but IIRC they used Jupiter to slingshot away from the planet. Am I remembering that wrong?

2010 : Odyssey Two - Jupiter Aero Braking Scene

http://videosift.com/video/2010-Odys...-Braking-Scene

psik