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Trek Tech Pass me the quantum flux regulator, will you?

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Old November 9 2008, 09:03 PM   #16
Christopher
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Re: How do Starships stop?

Albertus wrote: View Post
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According to the TNG Tech Manual, impulse engines reduce the inertial mass of a starship to make it easier to accelerate.......
The impulse engines utilise a small space-time driver coil which accelerates the impulse engine exhaust gasses to near-light velocities, without achieving warp.

Warp drive reduces the ships overall mass, not impulse engines.
Sorry, I think you're misunderstanding how it works. TNG TM p. 75, para. 2:
The propulsive force available from the highest specific-impulse fusion engines available or projected fell far short of being able to achieve the 10 km/sec^2 acceleration required. This necessitated the inclusion of a compact space-time driver coil, similar to those standard in warp engine nacelles, that would perform a low-level continuum distortion without driving the vehicle across the warp threshold. ...(I)t was determined that a fusion-driven engine could move a larger mass than would normally be possible by reaction thrust alone, even with exhaust products accelerated to near lightspeed.
In other words, reaction thrust alone, even with relativistic exhaust products, is not capable of accelerating a Galaxy-class starship's mass efficiently without the added contribution of the space-time driver coil. Therefore, the driver coil is making it possible to impart greater acceleration (a) with the same amount of force (F) -- which, by Newton's second law, means reducing its inertial mass (m).
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Old November 9 2008, 10:00 PM   #17
Albertus
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Re: How do Starships stop?

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.

The driver coils are localised and specific to the fusion reactors that they are connected to. No connection to warp anything. You seem to be confusing the ability to drive gas jets to near warp velocities with driving a ship to warp. Impulse cant do that, no matter if you strung all the driver-coils together.

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Old November 9 2008, 10:01 PM   #18
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Re: How do Starships stop?

Since they can cancel inertia inside the ship, maybe they can cancel it outside, as well? Perhaps the inertial damping fields can be extended to affect the entire ship's mass and affect it, accordingly.

So they just have the Impulse Drive stop "pushing" the ship and then cancel the vessel's inertia to the point it "stops" (matches the velocity).
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Old November 9 2008, 10:14 PM   #19
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Re: How do Starships stop?

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Since they can cancel inertia inside the ship, maybe they can cancel it outside, as well? Perhaps the inertial damping fields can be extended to affect the entire ship's mass and affect it, accordingly.

So they just have the Impulse Drive stop "pushing" the ship and then cancel the vessel's inertia to the point it "stops" (matches the velocity).
Tigger you win the prize, That was my solution as well. It's pointless looking at the drive components of a starship for a way to stop a vessel.

The IDF is a perfect way to slow and stop a ship. Action and reaction, simple physics.

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Old November 9 2008, 10:16 PM   #20
Ronald Held
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Re: How do Starships stop?

Given what we have seen on screen, there has to be a field component to the impulse drive, if for no other reason to reduce the inertial mass of the ship. Changing the shape of the field and intensity should allow it to accelerate and declerate quickly.
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Old November 9 2008, 10:17 PM   #21
ancient
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Re: How do Starships stop?

Air brakes.


Hey, it's on-screen. On Futurama.
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Old November 9 2008, 10:21 PM   #22
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Re: How do Starships stop?

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.
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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
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...... (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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Old November 10 2008, 02:57 AM   #24
GodThingFormerly
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Re: How do Starships stop?

Santaman wrote: View Post
I agree with you on this one, the way starships move around does suggest the impulse drive is indeed a coil drive specialised to work at slower then light speeds, also it would explain the tremendoes acceleration and the little fuel it uses.
We don't know how much fuel impulse engines require under normal circumstances, but if the NCC-1701 employs degenerate matter as reaction mass - say something like metallic hydrogen - it would to a certain extent explain, A). the Enterprise's on-screen performance for velocities < c, B). the apparent lack of fuel tanks that would otherwise take up ~99% of the vessel's interior volume, and C). the discrepancy between TMoST's 190,000 ton mass figure and Scotty's "almost a million gross tons of vessel" line in Mudd's Women.

TGT
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Old November 10 2008, 03:02 AM   #25
Cary L. Brown
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Re: How do Starships stop?

Albertus wrote: View Post
This is one thing about Trek Tech that has always puzzled me. How do starships stop?

We know from the on-screen commands and actions that a ship at warp speed can translate to a sublight velocity within a few seconds. It is the slowing down from near light speed to a zero velocity that poses the problem.

The impulse engines all point in the wrong direction to be used for a retro-jet action and the Saucer and Battle section thrusters are used for station-keeping and fine maneuvering/attitude control of the ship.

I know that this aspect of Trek ships was considered and the idea of 'reverse thrusters' was mooted but the solution never went further than that throw-away idea and there is nothing in the Tech manual or elsewhere to suggest a method..

So, how does a Trek ship stop?

I have my own solution, but I am interested to hear other peoples ideas.

Well, for warp drive (which is a reactionless, field-based system) that's something that happens as part of the "warp engine magic" so I'm guessing you're uninterested in that, and are really just concerned with the newtonian-flight model.

There are two main ways of looking at impulse among fandom. Some folks think it's also a "field-effect" system (that's non-canon but it can be argued from a science basis) while others think it's purely a newtonian thrust-based system. And a few, like me, think it's a combination of the two... using newtonian thrust inside of a "space-time bubble."

Well, for the TOS ship, the only engines we ever saw were the nacelles and the impulse deck (and to be fair, that was never defined, on-screen, as the impulse deck, nor were the nacelles ever officially described on-screen as the warp engines). This was by intent... MJ was given the direction to not ever define the technology too closely, but just to make it "look and feel real, but beyond our current abilities."

With the TMP ship, however, you have a lot more detail added, and there were not two, not three, but FOUR different "propulsion subsystems" on the 1701(r).

1) Warp Drive (in the nacelles)
2) Impulse drive (at the aft end of the saucer)
3) Reaction Control system (for orientation control, not for significant translational movement)
4) THRUSTERS.

Yes, it's that fourth one that people tend to forget (or to get confused with the RCS system or the impulse drive). But it was in the design.

If you have a model of the refit E, look closely at the spin of the secondary hull. There are four aft-facing cut-outs. Now, look at the forward edge, right adjacent to the deflector housing (on top). Four forward-facing cut-outs.

These are the thrusters... pure newtonian devices, essentially rocket engines used for low-speed manuevering. And this was always part of the design (remember in STVI... "thrusters ONLY, while in Spacedock")

SO...

1) perhaps it slows down purely using these.

Or,

2) perhaps it uses some vectoring "thrust reversers" on the impulse engines (either force-field based, or perhaps simply mechanical flaps we never saw).

Or,

3) Perhaps part of a planetary approach, which we never saw on-screen, involves the ship turning around and using its main impulse drive to slow itself (that's most likely in reality, I think, by the way)

Or,

4) Perhaps there are reverse engines behind panels someplace on the ship which we've also never seen (seems unlikely, but it's not impossible).

OR...

5) Perhaps they use some sort of field-effect "drag chute" which is somehow part of the subspace drive system (whether you think that's just warp drive, or if (like me) you think that subspace is also involved in "impulse" drive as its know in Treknology).
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Old November 10 2008, 03:24 AM   #26
GodThingFormerly
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Re: How do Starships stop?

Cary L. Brown wrote: View Post
3) Reaction Control system (for orientation control, not for significant translational movement)
I think it is safe to assume that roll, pitch and yaw maneuvers would be carried out with onboard momentum wheels and control moment gyros to minimize reaction mass consumption, just as it is done on present-day spacecraft on the order of, say, Lockheed Martin's A2100 Geosynchronous Satellite Bus.

Cary L. Brown wrote: View Post
4) THRUSTERS.

Yes, it's that fourth one that people tend to forget (or to get confused with the RCS system or the impulse drive). But it was in the design.

If you have a model of the refit E, look closely at the spin of the secondary hull. There are four aft-facing cut-outs. Now, look at the forward edge, right adjacent to the deflector housing (on top). Four forward-facing cut-outs.

These are the thrusters... pure newtonian devices, essentially rocket engines used for low-speed manuevering. And this was always part of the design (remember in STVI... "thrusters ONLY, while in Spacedock")
Who said those things are thrusters? Certainly not Andrew Probert. They aren't even indicated with that bright yellow color to warn dockyard workers of their presence a la the RCS packs.

TGT

Last edited by GodThingFormerly; November 10 2008 at 03:37 AM. Reason: Fixed links.
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Old November 10 2008, 03:26 AM   #27
Griffworks
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Re: How do Starships stop?

This is a great thread. I love this sort of Treknology discussion!

We need a popcorn eating emoticon here....
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Old November 10 2008, 03:32 AM   #28
GodThingFormerly
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Re: How do Starships stop?

Griffworks wrote: View Post
We need a popcorn eating emoticon here....


TGT
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Old November 10 2008, 03:37 AM   #29
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Re: How do Starships stop?

Aaaaaahhhh! Thank you kindly!
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Old November 10 2008, 03:37 AM   #30
Albertus
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Re: How do Starships stop?

Cary L. Brown wrote: View Post
s
Or,

4) Perhaps there are reverse engines behind panels someplace on the ship which we've also never seen (seems unlikely, but it's not impossible).

OR...

5) Perhaps they use some sort of field-effect "drag chute" which is somehow part of the subspace drive system (whether you think that's just warp drive, or if (like me) you think that subspace is also involved in "impulse" drive as its know in Treknology).
I had a good laugh when you said there were parachutes or rather 'drag shutes'. LOL

Last edited by Albertus; November 10 2008 at 12:28 PM.
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