posted
I did a search for this topic, in case it had come up before, but couldn't find one, so here goes.
We know that a starship can drop out of warp to sublight speed. But how does it slow down from relativistic speeds?
We know that the impulse engines can get up 3/4 impulse - which is relativistic - but what mechanism slows it down? The RCS? A 'space-brake'? Tecnincally, it should swing around 180� and slow itself with the impulse engines.
Anyone have any thoughts?
Registered: Jun 2005
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posted
The impulse engines seem to have a reverse setting.
-Star Trek: Generations "ALL ENGINES FULL REVERSE!!" *wets pants*
-Any episode of TNG where we see the Enterprise flying backwards, such as when they back away from the mysterioProbe in the "Barclay Gets Wicked Smart" episode before spinning around and going to warp.
posted
Ok, I know its all down to 'techno-babble', but at least they could try to make it plausible.
The "ALL ENGINES FULL REVERSE!!" comment makes sense, and yet is doesn't in the context of what we see on screen and even the 'physics' of Star Trek.
The 'backing away'I can live with, it could be the result of the RCS, but stopping from relativistic velocities!? No way.
The impulse propulsion system is just an incredibly powerful variation on rocket principles, but the ship is still subject to the Laws of Conservation of Energy - for every action, there is an equal and opposite reaction.
It just seems strange that nobody worries too much about achieving 'warp' speeds, and discussing endlessly how warp can be achieved but seems totally unconcerned as to how they do something as simple as stop a ship moving.
posted
Propellers can stop and rotate the other way to go reverse but impulse engines are monodirectional (sick). Maybe what happens during Impulse slowdown is that the impulse engines simply shut off (or lower their output if complete stop isn't the goal) and then the inertial dampeners or the deflector dish or whatever might be built into the saucer rim can project a forward-facing counter flow.
Registered: Aug 1999
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I understand your example of the propellers, and as you point out the impulse engines only work one way.
The only energy sources that project forward are the main deflector, the sensors, the Bussard Ramscoop's and the RCS. None of which are capable of affecting the ship in any appreciable way at any velocity other than a slow walk.
The RCS seems to contribute, along with the vectored thrust of the impulse engines in changing direction, but is not powerful enough to get the ship to slow from 3/4 light speed to a dead stop.
I can think of at least two ways that you could slow a starship from relativistic speeds, using 'Trek physics', but there has never been any explanation on the TV shows or films, as to how it happens. Just seems like a glaring oversight to me, given how much the rest of Trek is picked apart.
posted
I've heard all sorts of crazy theories as to how they slow down, from RCS combined with lowering the ship's inertial mass, to the warp engines acting as a kind of anchor. Unfortunately, this is one area (like the length of the Defiant!) that nobody seems to agree on.
posted
Except that in "The Nth Degree", they ordered the ship into reverse at impulse. The timing of the orders and the effects showed that they were flying backwards at half impulse, and it was only when the ship turned around to fly forwards that they went to full impulse.
-------------------- “Those people who think they know everything are a great annoyance to those of us who do.” — Isaac Asimov Star Trek Minutiae | Memory Alpha
Registered: Nov 2000
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posted
If I remember correctly, one of the tech manuals says there are forcefields that redirect the impulse thrust in order to change them from forward to reverse.
Registered: Mar 1999
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WizArtist II
"How can you have a yellow alert in Spacedock? "
Member # 1425
posted
My understanding is that when at warp speed, the ship is in a subspace pocket, so to speak, and when the ship comes out of warp, whatever speed it happened to be going prior to engaging the warp field would be the speed the ship will be traveling at. So if its doing 2500 mph thru some school zone when it warps, when it drops out it will still be doing 2500 mph. Perhaps the impulse engines have some sort of thrust reversers like some jet engines where a clamshell cover extends and forms a cone that sends the jet blast forward.
-------------------- There are 10 types of people in the world...those that understand Binary and those that don't.
Registered: Nov 2004
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posted
The helmsman just pops the clutch and shifts the tranny into neutral
-------------------- "Who cares if we bomb a few hospitals, it just means we got them a second time" Warrant Officer Robert Clift, CVN-71 OEF
Registered: Aug 2002
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posted
My impression of warp was that the warp engines envelop the ship in a subspace field which allows it to 'warp' and therefore travel faster than light. So in order to stop the ship at warp, wouldn't they just dissipate the subspace field and drop back into 'normal' space, from subspace?
-------------------- "Brave men are vertebrates: they have their softness on the outside, and their toughness in the middle" -Lewis Carrol
Registered: Jan 2005
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posted
That probably is how the slowing down is done at warp, yes.
At impulse speeds, it's canonically confirmed in dialogue and visuals that impulse engines CAN work in reverse; no two ways around that. HOW they do it is never canonically specified, though. Thrust-reversing forcefields on a super-duper rocket are one possibility, suggested by the TNG tech manual. Use of non-Newtonian propulsion in the first place is another possibility, and in some ways more "realistic" than what the TNG TM suggests (after all, we have extremely poor visual correlation between the ship's state of movement and the impulse nozzles' state of illumination - and several starships have their impulse engines placed so that they cannot even produce FORWARD thrust, let alone reverse, by ejecting matter from their nozzles!).
In addition to reversed impulse engines, it is of course possible that the ship has additional means of slowing down. Some sort of automatically deploying "subspace anchor" or "subspace drag chute" may be an integral part of the machinery or working principles of an impulse engine. Also, collapsing of the mass-reducing fields may be used for slowing down the ship. Such systems would bring the ship to a halt when most or all power fails; reversed impulse thrust would be used for further "stopping power" when in a great hurry.
OnToMars
Now on to the making of films!
Member # 621
posted
I seem to recall a rather large argument on this topic, what with member-made diagrams and everything. IIRC, the discussion actually got quite heated, pardon the pun, though hell if I could find it again.
-------------------- If God didn't want us to fly, he wouldn't have given us Bernoulli's Principle.
Registered: Jun 2001
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