Impulse engine(s) on the Nebula?
- Thread starter Vanyel
- Start date
I'm too lazy to properly link in a picture right now, but all the assorted incarnations of the Nebula have had teeny weeny grilles under the saucer aft rim, just below those spots where a Galaxy would have her saucer impulse engines.
See for example www.ex-astris-scientia.org for an article on the subject (the picture link http://www.ex-astris-scientia.org/articles/nebula/nebula-impulse.jpg
has to be cut-and-pasted to work).
Timo Saloniemi
Edit: Shit, the bbs keeps abbreviating the link! Sigh. Well, just go to the site, choose "starship articles" and then choose the one on the Nebula class variants.
See for example www.ex-astris-scientia.org for an article on the subject (the picture link http://www.ex-astris-scientia.org/articles/nebula/nebula-impulse.jpg
has to be cut-and-pasted to work).
Timo Saloniemi
Edit: Shit, the bbs keeps abbreviating the link! Sigh. Well, just go to the site, choose "starship articles" and then choose the one on the Nebula class variants.
Three main possibilities here:
1) The engines are usually mounted on the trailing edge of a flat saucer. It wouldn't be too difficult to vector their thrust forward, both above and below the saucer, to create the braking effect - just like today's jet engines do it. There could be mechanical deflectors, or more probably just fancy forcefields.
2) Here on Earth, decelerating is easier than accelerating, because we can apply friction to defeat the simplicity of Newton's laws. In outer space, there is no friction, nothing to grab onto for a slowing effect... Except that in Star Trek, there just might be such a thing! It could well be that one can "drop an anchor in subspace" to immediately slow down a ship, while the reverse of this process cannot be applied to accelerate the ship because subspace is a static medium that nicely ruins the symmetry of Newton's laws. "Subspace anchor" could easily be a built-in function of standard impulse coils; indeed, all such coils might act as subspace anchors when depowered, explaining how Trek ships come to a seeming halt when losing power.
3) Impulse engines apparently achieve the impossible, accelerating ships to near-lightspeed without carrying around massive amounts of fuel, by altering the inertial mass of the ship. If an impulse engine can first reduce the mass of a ship to a fraction of its rest mass and then apply thrust on that mass, what will happen when the mass of the ship is restored? Will it retain its original speed? Or will it rather retain its original momentum, meaning that the speed drops to a crawl when the mass increases to the full rest mass? If the latter is true, you have your impulse braking system right there, without needing a forward-pointing rocket nozzle.
Timo Saloniemi
1) The engines are usually mounted on the trailing edge of a flat saucer. It wouldn't be too difficult to vector their thrust forward, both above and below the saucer, to create the braking effect - just like today's jet engines do it. There could be mechanical deflectors, or more probably just fancy forcefields.
2) Here on Earth, decelerating is easier than accelerating, because we can apply friction to defeat the simplicity of Newton's laws. In outer space, there is no friction, nothing to grab onto for a slowing effect... Except that in Star Trek, there just might be such a thing! It could well be that one can "drop an anchor in subspace" to immediately slow down a ship, while the reverse of this process cannot be applied to accelerate the ship because subspace is a static medium that nicely ruins the symmetry of Newton's laws. "Subspace anchor" could easily be a built-in function of standard impulse coils; indeed, all such coils might act as subspace anchors when depowered, explaining how Trek ships come to a seeming halt when losing power.
3) Impulse engines apparently achieve the impossible, accelerating ships to near-lightspeed without carrying around massive amounts of fuel, by altering the inertial mass of the ship. If an impulse engine can first reduce the mass of a ship to a fraction of its rest mass and then apply thrust on that mass, what will happen when the mass of the ship is restored? Will it retain its original speed? Or will it rather retain its original momentum, meaning that the speed drops to a crawl when the mass increases to the full rest mass? If the latter is true, you have your impulse braking system right there, without needing a forward-pointing rocket nozzle.
Timo Saloniemi
Thanks Timo, I thought the engines would be located along the trailing edge of the saucer, like on the Galaxy class. It's just I don't think I've ever seen one lite up on screen. I also like your 3rd possibility on how a starship puts on the brakes in space without a engine facing the opposite direction. The first possibility though makes more sense for how a ship goes in reverse (as in The Undiscovered Country).
Here's a nice peek at the Nebula impulse engines at explorermedia.net:
http://www.explorermedia.net/main/e107_plugins/forum/forum_viewtopic.php?46
http://www.explorermedia.net/main/e107_plugins/forum/forum_viewtopic.php?46
...However, that artwork is not true to any of the Nebula variants seen onscreen.
Those Galaxy-style engines are not present on any of the physical models; the saucer is smooth at those locations. The CGI Nebula has visible but solid cowlings at the Galaxy saucer impulse engine locations, and the small grilleworks beneath are the actual engines.
Also, the artwork seems to make glow a different set of spots on the dorsal module... The original module has torpedo tubes very much like the ones on Kirk's movie ship, a pair forward and a pair aft, at module centerline; later refinements of the module add up to six seeming torpedo launcher muzzles on the aft surface of the module. The red dots in the trench, on the forward bows of the module, don't seem to be torpedo tubes on the onscreen ships.
(Nor is there a tube above the deflector dish, although there should be, considering that torpedoes seemed to emerge from there in ST:FC, and that the Phoenix was able to fire forward torpedoes in "The Wounded" without the benefit of the dorsal module. I like the addition in the artwork...)
Timo Saloniemi
Those Galaxy-style engines are not present on any of the physical models; the saucer is smooth at those locations. The CGI Nebula has visible but solid cowlings at the Galaxy saucer impulse engine locations, and the small grilleworks beneath are the actual engines.
Also, the artwork seems to make glow a different set of spots on the dorsal module... The original module has torpedo tubes very much like the ones on Kirk's movie ship, a pair forward and a pair aft, at module centerline; later refinements of the module add up to six seeming torpedo launcher muzzles on the aft surface of the module. The red dots in the trench, on the forward bows of the module, don't seem to be torpedo tubes on the onscreen ships.
(Nor is there a tube above the deflector dish, although there should be, considering that torpedoes seemed to emerge from there in ST:FC, and that the Phoenix was able to fire forward torpedoes in "The Wounded" without the benefit of the dorsal module. I like the addition in the artwork...)
Timo Saloniemi
Here's a good one for Nebula reference pix:
http://www.trekmania.net/the_fleet/utopia/fleet/nebula.htm
http://www.trekmania.net/the_fleet/utopia/fleet/nebula.htm
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^^^
Nowhere -- that's just someone's mediocre fan art.
Nowhere -- that's just someone's mediocre fan art.
Vanyel, please don't hotlink images like that. Webmasters don't like it.
Very good suggestions!
One further one I'd like to suggest is that perhaps the Nebula uses a unique propulsion system where the warp coils are used below c in some fashion.
In the TNG technical manual (I think) this has been explained away as never being particularly efficient or feasible, but I could imagine that perhaps the Nebula's prototype had this 'experimental' engine arrangement which ultimately proved to be far inferior to traditional separate impulse engines/coils, but nonetheless was 'good enough' for the full run of Nebula-class starships, which may not need as much maneuverability in their typical roles as frigates/freighters/light-explorers/AWACs-type ships than your average explorer/battleship design, like the Galaxy class.
Perhaps using your warp engines for sublight speeds may even mean a smooth acceleration all the way from zero to Warp 9 with no relativistic effects, whereas traditional Newtonian setups are apparently normally limited to 0.25c before the jump to Warp 1 must occur.
Many capital ships from other races lack visible impulse engines, so perhaps some of them have had more success with sublight warp than Federation scientists, or perhaps they consider the maneuverability trade-off to be acceptable in more situations.
Of course, it's undoubtedly an oversight by the model designer, but it's the job of trekkies to come up with in-universe explanations for this kind of error
This pretty much has to be true, otherwise it provides simple, unlimited free energy.
Up to a point free energy is implied by the Federation economics, at least the occasional comments that are made. But this would enable a starship to basicly run forever without fuel, apart from startup fuel.
Simple example, take a massive flywheel, use inertial dampers to speed it to near lightspeed, then turn off the dampers, and use the flywheel to generate as much conventional power as you will ever need.
The flaw might be, it takes a greater amount of energy to use inertial dampening in the first place. The technique then wouldn't really save energy, just time, you would be able to accelerate at a very high rate without flattening the crew and contents of the ship.
However in shows where the ship is at very low power, damaged, etc, the impulse engines still function, it can't take all that much power to move at impulse speed, so I'd go with the "loses speed when the dampers go off" theory.
Plecostomus
Commodore
To be sure, there's little reason to think that the Defiant has a "hidden" impulse system. After all, the ship has these red-glowing bits just inboard of the warp engine cowlings, looking very much like classic impulse engines.
The DS9 Tech Manual interpretation that these are escape pod ejection chutes and that the real impulse engines fire "stealthily" through the extreme stern is... Possible, I guess. The aft end of the ship does look a bit like the impulse assembly of Kirk's old ship. But it sounds like a needless complication, especially when we never hear that stealth would be a design criterion for the vessel in other respects.
Timo Saloniemi
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