Ventral saucer impulse engines on nuEnterprise?

[JonnyBoy]

Guys, the Impulse engines are on the back of the saucer, just as on the TOS-E. The red jets are thrusters. They can be seen firing briefly (on the topside of the saucer) when the Enterprise begins diving under the Mayflower's saucer over Vulcan in the side-on shot here:

 

[F. King Daniel]

Guys, the Impulse engines are on the back of the saucer, just as on the TOS-E. The red jets are thrusters. They can be seen firing briefly (on the topside of the saucer) when the Enterprise begins diving under the Mayflower's saucer over Vulcan in the side-on shot here:

How is it I never noticed that? Is it even visible on standard DVD?

 

[Sector 7]

^Don't feel bad. I had not noticed it until this thread. It looks as though JJ and company are getting more right than some have suggested.

 

[JonnyBoy]

I didn't notice until a few weeks ago. Its a neat touch, and one of several ILM was careful to include. Another one I like is when the nacelles power down after the Warp Core is ejected. The "fins" retract and the engines go dark in the shot from behind the ship.

My only qualm with the thrusters is that they seem redundant. I always understood that the four (or eight counting top and bottom) RCS thruster quads on the saucer's out edges were the maneuvering thrusters. Now I wonder what those are.

 

[OneBuckFilms]

I didn't notice until a few weeks ago. Its a neat touch, and one of several ILM was careful to include. Another one I like is when the nacelles power down after the Warp Core is ejected. The "fins" retract and the engines go dark in the shot from behind the ship.

My only qualm with the thrusters is that they seem redundant. I always understood that the four (or eight counting top and bottom) RCS thruster quads on the saucer's out edges were the maneuvering thrusters. Now I wonder what those are.

I'd say the thrusters we saw beyond the standard Quads may be for more radical maneuvering, or when an extra burst is needed, for instance to dodge debrit or push a livkely very heavy Starship out of a gravity well.

 

[Timo]

Andrew Probert designed something like that for the TMP ship, too: the yellow-coded maneuvering thruster clusters were accompanied by some heavier-duty rockets, in depressions looking like "NACA inlets" atop the secondary hull and thus close to the thrust line; apparently, they were for forward propulsion only.

Of course, for all we know, the TMP ship had other such thrusters elsewhere, under covers. Or then those "NACA inlet" things were something else altogether, despite the best intentions of the designer...

Timo Saloniemi

 

[JonnyBoy]

I didn't notice until a few weeks ago. Its a neat touch, and one of several ILM was careful to include. Another one I like is when the nacelles power down after the Warp Core is ejected. The "fins" retract and the engines go dark in the shot from behind the ship.

My only qualm with the thrusters is that they seem redundant. I always understood that the four (or eight counting top and bottom) RCS thruster quads on the saucer's out edges were the maneuvering thrusters. Now I wonder what those are.

I'd say the thrusters we saw beyond the standard Quads may be for more radical maneuvering, or when an extra burst is needed, for instance to dodge debrit or push a livkely very heavy Starship out of a gravity well.

I suspected as much. I would imagine those RCS quads would be inadequate for maneuvering such a massive starship in such a radical fashion.

 

[Cyke101]

Andrew Probert designed something like that for the TMP ship, too: the yellow-coded maneuvering thruster clusters were accompanied by some heavier-duty rockets, in depressions looking like "NACA inlets" atop the secondary hull and thus close to the thrust line; apparently, they were for forward propulsion only.

Of course, for all we know, the TMP ship had other such thrusters elsewhere, under covers. Or then those "NACA inlet" things were something else altogether, despite the best intentions of the designer...

Timo Saloniemi

I think you're on to something. For the longest time I wondered why Star Trek ships were so maneuverable despite the large newtonian-style impulse engines really only facing behind the ship and providing forward thrust. Thrusters/rockets of various sizes and various locations would be a plausible explanation for that.

 

[Glacial]

Guys, impulse engines aren't rockets. Thrusters are. I always assumed the impulse engines just send power to the warp coils, just not enough to get the ship over light speed.

That'd be the only way to explain why Kirk when stealing the Enterprise out of spacedock could order 1/4 impulse, and the ship went out backwards.

 

[Timo]

Or then thrust reversers.

I mean, since we don't see any impulse exhaust, ever, it could just as well be directed forward, or down, or to starboard, at times.

Although admittedly only the classic NCC-1701 and the -A look even remotely like the impulse engine assembly could be anywhere near the center of gravity, where Newtonian thrust would do any good...

Timo Saloniemi

 

[OneBuckFilms]

Guys, impulse engines aren't rockets. Thrusters are. I always assumed the impulse engines just send power to the warp coils, just not enough to get the ship over light speed.

That'd be the only way to explain why Kirk when stealing the Enterprise out of spacedock could order 1/4 impulse, and the ship went out backwards.

It would also explain why the Warp Engine glowed brighter when the Kelvin went to ram the Narada.

 

[Crazy Eddie]

Guys, impulse engines aren't rockets. Thrusters are. I always assumed the impulse engines just send power to the warp coils, just not enough to get the ship over light speed.

As it stands, impulse engines rarely (canonically) get the ship anywhere near light speed. In STXI it takes Kelvin sixty seconds to ram the Narada from a standing start something like six kilometers away; this gives you a terminal velocity of 200 to 300m/s when the ship finally impacts. Kirk's escape from space dock at "one quarter impulse power" has the ship departing at around 30mph. Likewise, Enterprise covers a distance of about 4000km in the three minutes and thirty seconds from the time Kirk orders "best possible speed," which directly implies accelerations between 5 and 15km/s^2, not too different from what you'd get from a conventional rocket engine.

My only qualm with the thrusters is that they seem redundant. I always understood that the four (or eight counting top and bottom) RCS thruster quads on the saucer's out edges were the maneuvering thrusters. Now I wonder what those are.

If they aren't maneuvering thrusters, I'd peg them for either sensor elements or (less likely) shield generators. I think shield elements are less likely, as those four T-shaped features on the back of the saucer are in a better place to be that, so probably part of a sensor system, using their wide separation to triangulate exact positions on distant objects.

 

[ALF]

Clinical? Or Critical? Or maybe even cynical....

Anyway, I just watched Trek XI again and they didn't make any mistakes. When Sulu said he'd use the thrusters I trusted him. I almost even thrusted him! You should trust (thrust) him too.

Let's come out of warp near a moon but let's do it together with enthusiasm. Just because it's an alternate universe doesn't mean we should start throwing each other out the airlock.

Tom Riley, thanks for the sceenshots.

James T.Shepard, welcome to the board.

 

[Tom Riley]

Guys, impulse engines aren't rockets. Thrusters are. I always assumed the impulse engines just send power to the warp coils, just not enough to get the ship over light speed.

That'd be the only way to explain why Kirk when stealing the Enterprise out of spacedock could order 1/4 impulse, and the ship went out backwards.

You don't think the impulse engines themselves provide thrust? Just that they send power to the warp coils... Ok, first, then why exactly do the impulse engines always have that glowing red area that is exposed to the outside of the ship? Not to mention, on the Enterprise D there are 3 impulse engines shown. The main impulse engine located at the base of the neck facing aft, and the two on the rear edge of the saucer facing aft. Now if those only propel the ship by providing power to the warp coils... then how is the Enterprise D supposed to move while the saucer is separated? Thrusters only? And why would they put them on the saucer if it could be separated?

 

[Timo]

Ok, first, then why exactly do the impulse engines always have that glowing red area that is exposed to the outside of the ship?

...And, interestingly enough, these things glow brightly even when the ship isn't moving at all. (Or at least not accelerating at all, for you Newtonian relativity purists). That more or less rules them out as rocket nozzles.

We know a ship can go to warp without impulse engines, as in "Obsession". We know a ship can go to impulse without warp engines, as is evidenced in every second Trek space battle. That sort of suggests that the systems are independent of each other. But it doesn't rule out the possibility of some sort of an interconnect for extra power, or in emergencies, or something special like that.

Timo Saloniemi

 

[OneBuckFilms]

Ok, first, then why exactly do the impulse engines always have that glowing red area that is exposed to the outside of the ship?

...And, interestingly enough, these things glow brightly even when the ship isn't moving at all. (Or at least not accelerating at all, for you Newtonian relativity purists). That more or less rules them out as rocket nozzles.

We know a ship can go to warp without impulse engines, as in "Obsession". We know a ship can go to impulse without warp engines, as is evidenced in every second Trek space battle. That sort of suggests that the systems are independent of each other. But it doesn't rule out the possibility of some sort of an interconnect for extra power, or in emergencies, or something special like that.

Timo Saloniemi

In Elaan of Troyius, the Enterprise is sluggish at maneuvering without Warp Power when fighting the Klingon ship.

This tells me that Warp power can be used to supplement impulse power for maneuvering.

 

[Crazy Eddie]

Ok, first, then why exactly do the impulse engines always have that glowing red area that is exposed to the outside of the ship?

...And, interestingly enough, these things glow brightly even when the ship isn't moving at all. (Or at least not accelerating at all, for you Newtonian relativity purists). That more or less rules them out as rocket nozzles.

Not necessarily. Technically, there's no reason for the engines to glow AT ALL, even if they do provide newtonian thrust. Unless of course the nozzle elements also double as heatsinks for the fusion reactors, in which case the only time they would NOT glow is when the reactors are shut down.

OTOH, the visuals from STXI explicitly have the impulse engines going dark just before the warp engines come online. This suggests that either the impulse engines ARE always providing thrust, or that the fusion reactors are powered down to a very low "idle" mode to conserve fuel while the ship's power systems switch over to EPS taps.

 

[Tom Riley]

Ok, first, then why exactly do the impulse engines always have that glowing red area that is exposed to the outside of the ship?

...And, interestingly enough, these things glow brightly even when the ship isn't moving at all. (Or at least not accelerating at all, for you Newtonian relativity purists). That more or less rules them out as rocket nozzles.

ACTUALLY, the Enterprise-D's secondary impulse engines on the back edge of the saucer were constantly dark. not to mention, I didn't say anything about the glow meaning it was in the middle of providing thrust, I was simply pointing out that it has an area specifically exposed to the outside of the ship, when, if it was simply to create power, it wouldn't need to be, and could be kept inside the center where it would probably be more protected. I only mentioned the glowing part to help reference that section I was talking about.

 

[Timo]

Acknowledged. And I don't think we should rule out some sort of a connection between warp and impulse propulsion, despite the evidence on the ability of one of these systems to operate while the other one's down.

Subspace fields are supposed to reduce inertial mass - a neat piece of magic often mentioned in backstage material but only appearing in canon a select few times, most prominently in DS9 "Emissary". It would make worlds of sense that a starship would use its warp field to reduce the inertia of maneuvering even when at sublight. Also, given that starships by design must have an abysmally low fuel-to-payload mass ratio and thus can't really fly around on conventional rockets even if acceleration performance outwardly is on par with such tech, it would be sensible to assume that mass reduction magic is always in use, even when warp engines are down.

Warp drive then probably doesn't directly provide "power" for sublight maneuvers, but facilitates them by erecting a powerful mass-reducing field. Impulse drive probably erects such a field as well, only of lesser power, and thus performs poorly when warp drive is down even if power aplenty is available. And impulse engines are likely to produce (fusion) power for ship's systems, just like backstage material suggests, thus justifying the constantly lit impulse engines in TNG: Picard doesn't want to rely on battery power alone even when there's no maneuvering to be done, so he keeps at least one impulse engine hot at all times. And in DS9, the wartime skippers of the Galaxies keep all three impulse engines hot and glowing, for even more power to the shields and weapons.

On top of all of this, the impulse engines may have some rocket function, too. I mean, if they exhaust their wastes, why not use that exhaust for rocket propulsion? It's a bit similar to having a turboprop engine on an aircraft: the main propulsive power comes from the propeller, but the hot exhausts of the turbine are often (but not always) vented to augment propulsion, sort of like a feeble jet engine. This would justify placing the impulse nozzles aft of the ship, even if they aren't exactly on the optimal thrust line or anything.

I gather that the hot red (or yellow or white) glow from the impulse engines is a feature associated with running the engines at very high power levels, and that many ship designs don't rely on or even allow for such levels. The engines of the TOS-R ship glow only when doing major impulse accelerations; the engines of the TOS movie ship glow more intensely in such situations, but always glow a bit when the ship is active; and the engines of the STXI ship, as said, go relatively dark when warp drive takes over (just like in TOS-R). The Galaxy could just be designed with a different power allocation doctrine in mind - while her near-sister Nebula does just fine without the excessive glow.

Timo Saloniemi

 

[Cobalt Frost]

The TNG Tech Manual says that impulse drives from the Ambassador-class on have a "compact space-time driver coil" that creates a mass-reduction field like you were talking about, Timo. It's probably not too much of a stretch to imagine that the nuPrise is similarly equipped. As far as propulsion, the impulse engines create a "high-energy plasma" that provides Newtonian thrust.

Also, the TNG Tech Manual's description of the Galaxy-class RCS makes them seem like mini-impulse engines: "gas-fusion reaction chamber.. ..and vectored-thrust exhaust nozzles." Personally, I imagine there's the main impulse drive, then the RCS "impulse" thrusters, then docking thrusters that are used for fine, precision movements.