Originally Posted By: Vuldan
*snipped out attack on my education* (for reference, I am studying astrophysics right now after completing my previous degree a few years back)

Regardless of common myth, "G", gravity exists, even in space. It's what holds the moon in place and most celestial bodies. The forces felt when a manned spacecraft accelerates, decelerates, or changes direction are not examples of gravity, but of inertia. They are called "G-forces" because they increase or decrease a person's apparent weight.

Newtons Law of Physics would still apply, as the turn of a space craft would be the same as that in a car, the difference is the amount of force external to the event. My point was designed to illustrate my immediate reaction, which was the effect would not, IN MY OPINION, be the same as that felt by a pilot in a Jet, but hell, I don't really know, I have never flown out of the atmosphere of earth.


Dunno why this all turned into a ragefest, but hopefully everyone has a splendid Easter.

Vuldan: your first comment stated two opposing views (or was at least worded poorly to give me that impression, if so, my apologies) as below -
"Interesting. G force is actually inaccurate, as it is a force of weight. It can result in death, although it's interesting to consider how it would actually effect you in space. Acceleration, deceleration and turns would cause force, but in a weightless environment. Cool stuff."

G-force isn't inaccurate, unless you mean the term itself. The only thing inaccurate about it is that someone chose to erroneously label it as a gravitational force when it has nothing to do with G fields. Yes, G-fields extend infinitely into the void of space at a strength of 1/r^2. Specifically, inertia is a property of all matter, not specifically because of a material's mass (weight is irrelevant beyond being a conversion factor of mass in a given g-field). All matter happens to have mass (which then factors into making inertia non-zero) due to another property of matter (currently believed to be the Higgs Boson)

The force is deceptively simple to calculate, other than making sure there are no issues with your vector math. You can (pretty much) completely ignore all local G because interstellar space is going to be infinitely close to zero, given all nearby sources of mass and the distances involved (come close enough to a celestial body and then it gets messy, but I have no idea if they modeled that portion or not). In this scenario, we'd basically only need to know the direction and acceleration at any moment (or the acceleration vector, if you will). We can derive the acceleration from the mass of the ship (your pilot mass is negligible, but we can throw it in for fun) and the force (thrust) exerted by the thruster(s) used to make the maneuver. Newton's laws would then state an equal force (inertia) would be exerted on the ship and its contents (pilot) in the opposite direction.

Ship from zero to x velocity with y acceleration gives a -y force as inertia in the opposite direction. Once at speed, there is no more inertia (no more acceleration, F=ma)

Ship from x speed to y velocity (either higher or lower) with z acceleration (positive or negative) gives an opposite force -z (negative or positive, respectively) as inertia to the pilot.

This can also be taken in a course change, a banked turn, an additional directional vector without modifying the original vector, etc. All of these forces are directly proportional to the thrust rating of the thrusters involved and the mass of the ship and pretty much all other forces will be negligible.

There was more that I was going to type, but I lost it (mental train derails ftw) but hopefully you understand where I (at least perceive) you to be incorrect in the italicized statement above.

EDIT for clarity:

F(thrusters applied) = m(system[ship+pilot+cargo]) * a(system) (we want to find the a of the ship)
so
a(system)=F(thrust)/m(system)

Then we can apply this a(system) to the mass of each object we want to analyze. The force exerted on a pilot's body would be F(body)=m(pilot+gear)*a(system)

At this point I can see where you would say mass (not quite weight, as you said) matters, but only after multiple derivations of values, and your mass stays relatively constant so it's also safe to say from a mathematical perspective that only the acceleration of the system matters. (the constant is applied, but constantly, so it isn't a variable, unless you can gain/lose weight(mass) in the game, lol)

Last edited by Hobbitlauncher; 04/20/14 06:24 AM.
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