A Peek Behind the Wing Commander Curtain (November 14, 2013)

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Finder of things, Doer of stuff
Chris Roberts is hard at work building Star Citizen, yet still finds time to discuss things like the game's physics with fans on the RSI forums. Chris was actually studying physics at Manchester University when he decided to switch paths and make games full time. In a series of recent posts, he also had some interesting revelations regarding the Wing Commander engine and its physics implementation. It's a fascinating (and detailed) look at an aspect of the game many haven't thought about:


...The idea is that the basic / beginner / simple IFCS will be set up to make flying around pretty simple and intuitive. It will take the pilot's inputs and map them to behavior similar to Wing Commander / Privateer - you control the orientation of your ship and set a desired velocity, the IFCS tries to achieve a velocity vector matching your forward vector multiplied by desired speed - which was actually how Wing Commander / Privateer actually worked - it was a basic Newtonian under it all despite popular belief - its why you would "slide" when you hit afterburners and tried to turn - normally there was enough excess thrust for maneuvering to adjust the velocity fairly instantaneously but as the speed got higher it would take a little while to correct to the desired velocity vector...

...as WC is concerned the ships had two thrust ratings - a "Maneuvering" thrust rating and a "Main" thrust rating. The maneuvering thrust rating was used to adjust the velocity vector outside the main thrusts direction (which was always forward). IT was assumed the maneuvering thrust could be applied in any direction (Other than forwards which the main thrust took care of) WC did use a basic Newtonian model (I should know as I programmed it!) but it was simplified in terms of simulating the ships ability to apply force to change its velocity vector, with the simulation of the thrusters abstracted to a maneuvering and main thrust ability per ship.





Image by Bearcat.

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Original update published on November 14, 2013
 
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Bearcat

Captain
I had the honor of meeting Chris a few months ago, and over some Mexican food we got into it about this subject of physics in space. The long complicated discussion ends up boiling down to Chris explaining that the faster a ship goes the more force the pilot will be experiencing in order to make a turn of equal proportions. This is true, but I still don't see how that relates to the game. Going faster does not increase the power of the thrusters. The force exerted on the pilot will be the same no matter how fast the ship was going. G-forces are all about acceleration. High speed turns only produce high G's in an atmosphere.

It is good to see him talking about the game mechanics. The crowd funding aspect seems to sap most of his attention in one form or another.
 

Ijuin

Admiral
High speed turns produce high acceleration in atmosphere because vector and facing are strongly coupled--any turning away from the airstream puts aerodynamic forces on your aircraft that will either force you to turn back into the airstream or else force your vector to change to match your facing. In vacuum however the only forces are gravity (pulling you towards a freefall path) and your own thrust.

That said, for craft in Wing Commander (and Star Citizen), that apparently regularly accelerate at rates ordinarily unsurvivable to humans, it is implied that there is some kind of technological mitigation in effect--the "acceleration absorbers" referenced in the damage reports in WC1/2. When fully functional, they seem to keep the "g-forces" down to a level that is safe, if uncomfortable to rookies.

This extremely high acceleration is the reason why most players don't notice the Newtonian model underlying the spaceflight, since it takes only about five seconds for most craft to go from a standstill to their maximum speed. Thrust dominates over inertia at such high acceleration. We will likely notice the effects of inertia more in Star Citizen, given that we will be able to mount thrusters of varying strength on our craft, which would mean that lower-thrust craft will have to contend with markedly slower acceleration, if not also a lower maximum speed.
 

Quarto

Unknown Enemy
That said, for craft in Wing Commander (and Star Citizen), that apparently regularly accelerate at rates ordinarily unsurvivable to humans, it is implied that there is some kind of technological mitigation in effect--the "acceleration absorbers" referenced in the damage reports in WC1/2. When fully functional, they seem to keep the "g-forces" down to a level that is safe, if uncomfortable to rookies.
Are we ever actually told what acceleration absorbers do? Because the idea that they keep g forces down to a safe level seems to be questionable, given that you can continue to fly with the accel absorbers destroyed.
 

Ijuin

Admiral
IIRC, the game increased your ship's inertia when they were damaged/destroyed, but not to a debilitating level. While within the storyline they would have to reduce acceleration a thousand-fold to allow the zero-to-400 km/s in five seconds that we see, within the game the loss of the system only seems to cut your acceleration by a factor of 2-3 at most, usually less. It's largely a matter of gameplay vs. story segregation.
 
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