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Old November 10 2008, 02:40 AM   #23
Christopher
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Re: How do Starships stop?

Albertus wrote: View Post
Christopher wrote: View Post
...... (a) with the same amount of force (F) -- which, by Newton's second law, means reducing its inertial mass (m).
There is no way that impulse engines can reduce mass for the Saucer section, or indeed, reduce mass for anything other than the exhaust gases produced by the impulse engines. I have the same manual, and I still don't see how you can get to your conclusion.
It's right there in the words I quoted. It says outright that even the highest specific-impulse thrusters cannot accelerate a Galaxy-class ship fast enough. That tells you unambiguously that accelerating the exhaust to any speed is not going to impart enough acceleration by itself. If the driver coil does boost the acceleration to an effective degree, it therefore must be by some means other than accelerating the exhaust gases.

Also, it's elementary that reducing the mass of the exhaust gases would reduce thrust, not increase it. It's the equivalent of having a smaller amount of propellant, and there's no way less propellant equals more thrust. So I can't understand why you'd think that would be the intent. If you want higher acceleration, you need a higher ratio of propellant mass to vessel mass -- or, phrased another way, a lower ratio of vessel mass to propellant mass. Since there's no propulsive benefit in reducing the mass of the propellant, the intent can only be to reduce the mass of the vessel.


The driver coils are localised and specific to the fusion reactors that they are connected to. No connection to warp anything.
Second part first: I never said they were connected to warp drive, except in the sense explicitly spelled out in the TM that they use a low-level warp field (i.e. below 1000 millicochranes and thus below the lightspeed threshold). You're reading things into my words that I'm not claiming.

As to the first part: The warp engines' driver coils are "localized" to the warp nacelles, but their field is large enough to encompass the entire ship and a surrounding "bubble" of space. Clearly such coils are able to have influence at a distance. It's just that the driver coils in the impulse engines are fewer in number and therefore less powerful; their effect can be just as broad but less intense, so that the spacetime distortion is not enough to create a warpfield but is sufficient to "flatten" the ship's gravity well and reduce its inertial mass.


Deimos Anomaly wrote: View Post
Probably ST ships use a forcefield setup to direct engine thrust and can redirect it forwards using this.. similar to the physical thrust reversers on aircraft.

It's a concept explored in a number of Sci-fi works. The SW EU for example calls it an "etheric rudder". But it's the same thing. Forcefields used to vector engine thrust in the desired direction.. including 180 degrees for reverse thrust.
Hey, that's a good idea. I hadn't thought of that, and I've had occasion to try to figure out how reverse impulse could work.


And ancient, where was the "air brakes" joke used in Futurama? I remember it from a Bugs Bunny cartoon, but not from there.
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