Author Topic: Sci-fi physics question (Read 570 times)

Knightsky · « **on:** June 18, 2006, 12:14:38 PM »

Okay, a question has came up during a sci-fi PBP game I'm running on another forum (the system we're using is Cinematic Unisystem, if that proves to be relevant). Our heroes are involved in a dogfight-in-space, the trouble being that the ship our heroes are using doesn't have a working antigrav drive for creating internal gravity at the moment. They're not inside the gravity pull of the nearby gas giant, but the question still came up of just how much of a problem G-forces are going to be with their ship whizzing and manuevering around without any internal gravity to compensate against that sort of thing.

Any ideas?

Thjalfi · « **Reply #1 on:** June 18, 2006, 01:12:40 PM »

it's gonna be a BIG problem. depending on how fast the ships are going, what kind of acceleration they pull, etc... the characters would be passing out or even dying due to extreme gravity changes on a regular basis.

to give you an example: the pilots of the blackbird, IIRC, had to wear special pressure suits when they took that thing for a flight, because it was going so fast that they couldn't survive without something ot help mitigate the serious gravity effects.

It's one of the main problems with space dogfighting - at the speeds more spacefighters travel, there has to be something like Artificial Gravity or an Inertial Dampener, otherwise the pilots are hosed.

ColonelHardisson · « **Reply #2 on:** June 18, 2006, 03:12:41 PM »

Quote from: Thjalfi

It's one of the main problems with space dogfighting - at the speeds more spacefighters travel, there has to be something like Artificial Gravity or an Inertial Dampener, otherwise the pilots are hosed.

Yep. Remember, no gravity doesn't mean no mass. David Weber makes makes it a point in his "Honor Harrington" novels to show the importance an "inertial damper" has to a starship crew by occasionally mentioning how a crew became a thin red past on the bulkheads during violent maneuvers or high acceleration when the "inertial dampers" were rendered inoperable. If the ship in question is maneuvering or accelerating at anything like 7+ gees (not even that mauch, really, when violently maneuvering), the crew is likely to die. Being thrown around by violent manuevers at what feels like 7 times your body weight just isn't healthy.

Dacke · « **Reply #3 on:** June 18, 2006, 03:48:01 PM »

It depends on what sort of accellerations they're pulling. According to wikipedia, fighter pilots usually start experiencing "greyouts" (problematic stuff, but not loss of consciousness) at 6-8 G, and blackouts at 9 G. That's with modern-day pilot suits designed to ameliorate the effects of accelleration, it's altogether possible that if you have the capability to build space fighters, you can also get better pilot suits (or you might not bother if you have inertial dampers/artificial gravity to compensate).

Now, not all space RPGs are equal when it comes to how much accelleration their ships can pull. One one hand, you have Traveller, where spaceships generally have accellerations rated in single-digit Gs. On the other hand, you have Alternity, where accelleration is measured in megameters per phase per phase (phase = 3 seconds, so roughly 100s of km/s^2, or 10,000 G).

Thjalfi · « **Reply #4 on:** June 18, 2006, 08:48:35 PM »

Quote from: ColonelHardisson

Yep. Remember, no gravity doesn't mean no mass. David Weber makes makes it a point in his "Honor Harrington" novels to show the importance an "inertial damper" has to a starship crew by occasionally mentioning how a crew became a thin red past on the bulkheads during violent maneuvers or high acceleration when the "inertial dampers" were rendered inoperable. If the ship in question is maneuvering or accelerating at anything like 7+ gees (not even that mauch, really, when violently maneuvering), the crew is likely to die. Being thrown around by violent manuevers at what feels like 7 times your body weight just isn't healthy.

doesn't help that weber's ships are accellerating at something like 7000 gravities. that's a very thin red paste, if the dampeners fail.

Dacke · « **Reply #5 on:** June 19, 2006, 04:49:58 AM »

Oh, and remember that travelling at high speed is relatively unproblematic. The problems come up when you want to make a change in course and/or speed.

Nicephorus · « **Reply #6 on:** June 19, 2006, 11:55:10 AM »

It totally depends on the details of the fictional universe.

For a thumbnail estimate, 1 G a change in velocity of 10 meter/seconc in one second. (not quite but makes math very easy)

Example: If you can get up to lightspeed(300,000 km/s) in 5 minutes, that's 1,000,000 G, totally dead.

But it also depends on the background on whether the you're doing actual Newtonian movement or some sort of apparent motion. For example, in Traveller 2300, the stutterwarp creates micro wormholes to instantly move a ship a km or so, and does this several times a second (I remember the concept but not exact number). Ships appears to move but wouldn't have any inertial effects. In this case, artificial gravity just makes it easier to mover around and have stuff stay put, but the effects wouldn't be huge.

Trek warp drives do something similar.

Knightsky · « **Reply #7 on:** June 19, 2006, 06:34:40 PM »

Thaks for all the input.

The engineer spent a Drama Point to jury-rig the antigrav drive, just enough to neutralize the effects of acceleration and g-forces, which will get them through the fight (assuming they don't get blown to smithereens).

Bagpuss · « **Reply #8 on:** June 20, 2006, 10:00:39 AM »

Without Inertial Dampers they would have to stick to reasonable G turns and be strapped into their seats at all times. Now if the opponent doesn't have inertial dampers you are fine as they will also be in the same boat.

If they do, then you are effectively as good as dead as they will be able to out accelerate, break and turn you, thus you will always be dead centre in their crosshairs and you will find it near impossible to get them in yours.

They can also walk about and do damage control and the like.

Oh and stutterwarp is cool.