Star citizen Flight model (post 2.0) thoughts from Nimrod77

I think you're completely right about waiting for the forward thrusters to ramp down before firing the reverse ones. It's the kind of thing you would write down on paper when designing the system and not realize that it doesn't match up with the way the ship engines work. I'll explain why this behaviour is not necessary to maintain new flight model.

  • Every different engine/thruster output value corresponds to a force on the ship.
  • The sum of forces on the ship corresponds to the acceleration of the ship (with a factor for the mass, but that doesn't change unless you toss someone overboard).
  • Jerk corresponds to linearly changing acceleration. If your ship has only one engine, and that engine's output is changing linearly (i.e. ramping up), then the force (which is the only force, thus the sum of forces) is changing linearly, and the ship's acceleration is correspondingly changing linearly. That is, the ship is experiencing jerk.
  • This is physically motivated: it's unlikely that an engine can instantaneously change its output.
  • It can also help things feel more "normal", since we usually experience jerk due to friction forces on Earth (given a constant engine output, you don't continuously accelerate since the friction forces rise as your velocity rises, so the sum of forces is non-constant).

The problem (in my opinion, and I think nimrod's as well from his comment) comes about when you have multiple engines.

  • Engines can have a ramp up/down time, that's not a problem and probably desirable from a gameplay point of view.
  • The ramp down time could be very fast, but that's a design decision.
  • BUT what seems to have happened is that a "jerk" value was modeled for the overall acceleration of the ship, not the force applied by the individual thrusters.
  • What I think should happen is the one set of thrusters should ramp down (possibly very fast), and the other set should simultaneously ramp up (maybe slowly). If the ramp up/down times are different, then the ship would experience two jerk values during the transition. This is closer to what the physical situation might be.
  • Instead, what I think does happen (from the video), is that a single jerk value is applied throughout the transition. As if a single engine was controlling both the forward and backward force.

Of course some of this comes down to design decisions, and implementation considerations. But my guess is that it might feel (or at least look) more intuitive if the individual engines had ramp up/down times, instead of the overall acceleration being subject to a ramp up/down time.

/r/starcitizen Thread Parent Link - youtube.com