Impulse Engines: Newtonian Physics or Non-Newtonian?

[Cary L. Brown]

http://www.ocii.com/~dpwozney/apollo1.htm

Oh and what is that then?

Spacecraft DO have an exhaust plume/trail when in space.

As for the site itself, was the first one that showed me what I wanted to see.

Sorry, no... that's not an exhaust trail.

Of course, the instant that gas is expelled, it is visible. In fact, since it's not going into an already-existing medium, it's MORE visible. But that's not a counterargument, as you seem to be saying it is.

See, an "exhaust trail" lingers for more than a fraction of a second. Rocket engines, in atmosphere, leave a long trail of smoke and vapor. High-flying aircraft leave contrails and vapor trails. Ground-to-air missiles leave exhaust trails.

The reason that they do this is that the expelled exhaust is able to linger once it has reached the same pressure as the local atmosphere. It dissipated eventually, but once it expands to reach atmospheric pressure, if the air was perfectly still, it would only dissipate through "brownian motion."

In space... well... I hope you can see why this couldn't happen. You NEVER reach "equilibrium" and you never reach equalization of pressure between the expelled exhaust and the surrounding medium... because there IS no "surrounding medium." It dissipates, and continues to dissipate, essentially forever. And, obviously, while in an atmosphere the rate of dissipation slows as you approach equilibrium, in space, the rate never slows.

That's why there are no "exhaust trails" in space.

Make sense?

 

[Santaman]

That still doesn't explain why there is absolutely NOTHING expelled from impulse engines, they just glow just like warp drives do and thats it.

 

[Myasishchev]

I believe there are two things going on. The first is some confusion over when warp could be used. In TMP, it was dangerous to use warp inside a solar system (notwithstanding it would require FTL travel to get out of the system in a reasonable time to begin with, and the use of warp inside systems quite often in TOS). The second is that warp was costly to depict during TNG. They needed to have ships in normal space as much as possible so they didn't have to have the "warping" effect.

Yet it wouldn't require FTL to ascend vertically in relation to the ecliptic where a clear line of sight could be had to open space. Then again I doubt the asteroid belt is dense enough (or yet too unmapped and uncatalogued--in the 23d century!) that that would be necessary, unless the warp field is several hundred or thousand kilometers in diameter.

Then again, we don't know if it's ordinarily celestial objects which are dangerous to starships (apparently dangerous enough for the Enterprise in TMP), or starships that's dangerous to celestial objects. Who knows what the gravitational effects of a warp drive in a solar system are. Might throw a comet on an intercept course with the Earth, or more likely throw a sublight asteroid miner on a slow course into the sun.

Even more likely, it's the surely enormous interplanetary traffic which is put in danger. If so, can we finally square the incongruous order for warp speed in the atmosphere in TVH? The 1980s had comparatively very little commercial space traffic (and yet Kirk surely screwed up a satellite constellation or two with his thoughtlessness).

As for impulse-only battles of the TNG/DS9 era, I assumed that was because combatants had developed means of keeping the other side from going superluminal. BoBW has the E-D breaking a Borg cube out of warp, surely it's no more difficult to do it to a Cardassian ship of the line.

 

[buzzknox]

It's possible that the engagements we saw were preceeded by waves of "jammer" drones/torpedoes that disrupted warp fields. That would be out of character for the shows which depicted electronic warfare most often by not having it at all.

A possible "in universe" explanation is that warp battles between fleets would be too difficult to manage effectively. You'd have all the problems inherent in a dog fight but several orders of magnitude greater due to the higher speeds involved. It might be easier to hit enemy vessels through accidental collisions than deliberate action. So, fleets engage at sublight just so they can engage the enemy effectively.

 

[Cary L. Brown]

That still doesn't explain why there is absolutely NOTHING expelled from impulse engines, they just glow just like warp drives do and thats it.

That's not true, though. We know that there's SOMETHING expelled... at least in more recent movies and series. Hell, Chang's BOP was destroyed because of that!

The "real" answer to your query is simple... it's easier to have primary-color-LEDs than it is to do a realistic portrayal of something like this.

I, personally, absolutely DESPISE the "primary color LEDs" approach to "Treknology" which we've seen from early TNG through... well, through the most recent movie. "Red LED = Impulse, Blue LED = warp engine or deflector." (sigh) I liked the TOS effects better, and at least the TMP effects (while, being too "lighting oriented" IMHO) at least didn't have that annoying "primary colors = technology" issue - best illustrated by the behavior of the deflector dish (starting at "plain ceramic," then glowing a dull warm orange, and gradually "heating up" to a brilliant blue/white).

As far as I'm concerned... when impulse engines fire, there should be a slight, nearly-imperceptible "fuzzy incandescent" trail immediately behind the engine exhaust. That we've never been able to clearly see this is due to the fact that we've never seen a real starship, only SFX shots intended to represent real starships, succeeding or failing to various levels.

 

[Cary L. Brown]

Then again, we don't know if it's ordinarily celestial objects which are dangerous to starships (apparently dangerous enough for the Enterprise in TMP), or starships that's dangerous to celestial objects. Who knows what the gravitational effects of a warp drive in a solar system are. Might throw a comet on an intercept course with the Earth, or more likely throw a sublight asteroid miner on a slow course into the sun.

Well, I suspect it's just a navigational problem... going that fast, you're more likely to run into something... even computer-assisted navigation has got to have limits.

Besides, we've seen plenty of times that our heroes went to warp in-system. Typically low warp, (WF1, WF2, WF3) but warp nevertheless. And if you can't go to warp in-system, how do you go back and save whales???

 

[Santaman]

That's not true, though. We know that there's SOMETHING expelled... at least in more recent movies and series. Hell, Chang's BOP was destroyed because of that!

The "real" answer to your query is simple... it's easier to have primary-color-LEDs than it is to do a realistic portrayal of something like this.

I, personally, absolutely DESPISE the "primary color LEDs" approach to "Treknology" which we've seen from early TNG through... well, through the most recent movie. "Red LED = Impulse, Blue LED = warp engine or deflector." (sigh) I liked the TOS effects better, and at least the TMP effects (while, being too "lighting oriented" IMHO) at least didn't have that annoying "primary colors = technology" issue - best illustrated by the behavior of the deflector dish (starting at "plain ceramic," then glowing a dull warm orange, and gradually "heating up" to a brilliant blue/white).

As far as I'm concerned... when impulse engines fire, there should be a slight, nearly-imperceptible "fuzzy incandescent" trail immediately behind the engine exhaust. That we've never been able to clearly see this is due to the fact that we've never seen a real starship, only SFX shots intended to represent real starships, succeeding or failing to various levels.

Every starship will expell what comes out of the fusion reactors, for that purpose its indeed most likely that they use the primary red led coloured exhaust port, that I have no issues with, the thing is that I don't for a second believe is that this provides any actual thrust for all the reasons I've stated before.

I guess thats about all I can say about it which probably means we'll have to agree on disagreeing which is okay. as for the rest, I am very much enjoying your thread in Trek Art.

 

[USS Jack Riley]

That still doesn't explain why there is absolutely NOTHING expelled from impulse engines, they just glow just like warp drives do and thats it.

Santaman - I have suggested this as a rationale in other situations in which this issue came up. think of the impulse exhaust ports as the exhaust pipe on your car. It isn't the exhaust pipe that moves your car, but the wheels. You can rev the car all you want, with all the resultant exhaust, but if you don't have wheels on the ground, you get zero acceleration.

This also helps explain how the Enterprise destroys Chang's BoP - the photon torpedo followed the plasma trail (actually probably the resulting radiation trail) left from the BoP's impulse exhaust vents to track and hit the BoP.

This explanation also explains how a ship can move backwards using impulse, even if the exhaust, if the true mode of acceleration, would only indicate a forward acceleration possibiolity. Clearly, RCS thrusters cannot overcome the momentum of the Enterprise at impulse when Kirk yells to back up.

YMMV

 

[Unicron]

I thought blinky lights were an essential key to sci-fi.

 

[Santaman]

That still doesn't explain why there is absolutely NOTHING expelled from impulse engines, they just glow just like warp drives do and thats it.

Santaman - I have suggested this as a rationale in other situations in which this issue came up. think of the impulse exhaust ports as the exhaust pipe on your car. It isn't the exhaust pipe that moves your car, but the wheels. You can rev the car all you want, with all the resultant exhaust, but if you don't have wheels on the ground, you get zero acceleration.

This also helps explain how the Enterprise destroys Chang's BoP - the photon torpedo followed the plasma trail (actually probably the resulting radiation trail) left from the BoP's impulse exhaust vents to track and hit the BoP.

This explanation also explains how a ship can move backwards using impulse, even if the exhaust, if the true mode of acceleration, would only indicate a forward acceleration possibiolity. Clearly, RCS thrusters cannot overcome the momentum of the Enterprise at impulse when Kirk yells to back up.

YMMV

Yeah I know what you mean, thats my take on it as well, fusion reactor driven coil drive which in case of the TMP refit can even use warp power to drive the sublight coils and the exhaust thing on the back of the saucer just being that, a way to get rid of the stuff fusion reactors spit out and conveniently get rid of heat that way as well.

Hmm, weren't there even cases that impulse drive even worked on the emergency batteries?

I thought blinky lights were an essential key to sci-fi.

Blinking light rule..

 

[USS Jack Riley]

Hmm, weren't there even cases that impulse drive even worked on the emergency batteries?

I don't remember such an episode, but that doesn't mean there wasn't one.

Furthermore, according to Mr. Scott's Guide to the Enterprise, the Enterprise's backup power (it's batteries) were small fusion reactors located in A or B deck (I want to say A deck).

Either way, blinky lights resolve the issue.

 

[Crazy Eddie]

That still doesn't explain why there is absolutely NOTHING expelled from impulse engines

We don't know that... we just don't SEE it. There's nothing expelled from the RCS thrusters either despite the fact that they ARE thrusters and in the script for TMP we were supposed to see something expelled from them, but didn't, because of VFX complications.

 

[Santaman]

^^ I only know one occasion where you can see the thrusters fire and thats TNG's "Booby Trap" which like the thrusters on the shuttle has a plume you can see and again the impulse engine that fires once to give the ship a boost only glows bright for a moment.

Another detail is that impulse engines seem to have the same "glass" cover as the warp engines, any thoughts about that?

 

[trevanian]

That still doesn't explain why there is absolutely NOTHING expelled from impulse engines

We don't know that... we just don't SEE it. There's nothing expelled from the RCS thrusters either despite the fact that they ARE thrusters and in the script for TMP we were supposed to see something expelled from them, but didn't, because of VFX complications.

I've never seen any fx guy or production person address this before. What makes you think that we were supposed to see thruster action besides a script reference?

 

[Myasishchev]

Then again, we don't know if it's ordinarily celestial objects which are dangerous to starships (apparently dangerous enough for the Enterprise in TMP), or starships that's dangerous to celestial objects. Who knows what the gravitational effects of a warp drive in a solar system are. Might throw a comet on an intercept course with the Earth, or more likely throw a sublight asteroid miner on a slow course into the sun.

Well, I suspect it's just a navigational problem... going that fast, you're more likely to run into something... even computer-assisted navigation has got to have limits.

Besides, we've seen plenty of times that our heroes went to warp in-system. Typically low warp, (WF1, WF2, WF3) but warp nevertheless. And if you can't go to warp in-system, how do you go back and save whales???

By going clockwise.

I dunno, celestial objects should be exquisitely catalogued by the 23d and 24th centuries. It seems like there should be few surprises regarding the sun's predictable and natural satellites.

 

[JNG]

^Just for clarity's sake, it doesn't seem to be that you can't go into warp inside a solar system so much as you shouldn't. If I remember correctly, this is one of those guidelines typically quoted just before it is not adhered to. If we look at the danger and seeming exoticism of the slingshot maneuver, it seems largely consistent with this idea in that it is a very specialized and tricky use of warp in an environment where it is not typically used (close to a system's primary).

 

[Ronald Held]

I have not read every post here, but if the impulse exhausts consist of high energy particles radiating far above the visible and moving maybe 100s of km/secs, why would you expect to see the EM radiation?

 

[Crazy Eddie]

^^ I only know one occasion where you can see the thrusters fire and thats TNG's "Booby Trap" which like the thrusters on the shuttle has a plume you can see and again the impulse engine that fires once to give the ship a boost only glows bright for a moment.

Which--given the fact that Federation starships have been using "thrusters" for a hundred years prior to "Booby Trap" for maneuvering--kind of illustrates my point, doesn't it? MODERN engines (by Trek standards) do not have visible exhaust plumes. They do leave ion trails, though (see "Relics") that are visible to any halfway decent sensor system.

The shuttle's thruster plume is visible because it's a sub-sonic expulsion of hydrazine gas; E-D's emergency thrusters are probably just as primative and therefore visible. Her maneuvering thrusters do not leave visible emissions, and nor would the impulse engine unless it was expelling slightly warm hydrogen several tons a second at less than four hundred miles per hour.

Another detail is that impulse engines seem to have the same "glass" cover as the warp engines, any thoughts about that?

They don't. Tech manual describes them as possessing bell-shaped nozzles for thrusters. On the other hand, they kind of resemble modern ion thrusters , which may or may not just be a coincidence.

 

[Crazy Eddie]

That still doesn't explain why there is absolutely NOTHING expelled from impulse engines

We don't know that... we just don't SEE it. There's nothing expelled from the RCS thrusters either despite the fact that they ARE thrusters and in the script for TMP we were supposed to see something expelled from them, but didn't, because of VFX complications.

I've never seen any fx guy or production person address this before. What makes you think that we were supposed to see thruster action besides a script reference?

The cues for thruster action are in the TMP script, for example, during the departure sequence, but during the film these are replaced with a very dramatic "turning on the flood lights" moment. The script calls for "thruster jets firing" after Kirk's "thrusters at stationkeeping" order, but IIRC the effect that ILM came up with looked too much like the normal flashing of running lights (just a blinking yellow thing) and was therefore dropped. You see a smaller scale example of this in the deleted scene where Kirk leaves the Enterprise in his space suit; the corners of his thrusters flash yellow along with the hissing sound effect, consistent with script cues.

I should note, however, the really curious fact that these thruster flashes ARE present on the ST-XI Enterprise; for example, as the ship ascends after dropping out of warp in Titan's atmosphere, there's the distinct flickering of red lights on the bottom of the saucer from what are, apparently, intended to be some kind of landing thrusters.

 

[trevanian]

We don't know that... we just don't SEE it. There's nothing expelled from the RCS thrusters either despite the fact that they ARE thrusters and in the script for TMP we were supposed to see something expelled from them, but didn't, because of VFX complications.

I've never seen any fx guy or production person address this before. What makes you think that we were supposed to see thruster action besides a script reference?

The script calls for "thruster jets firing" after Kirk's "thrusters at stationkeeping" order, but IIRC the effect that ILM came up with looked too much like the normal flashing of running lights (just a blinking yellow thing) and was therefore dropped. You see a smaller scale example of this in the deleted scene where Kirk leaves the Enterprise in his space suit; the corners of his thrusters flash yellow along with the hissing sound effect, consistent with script cues.
.

I remember little animation flashes when you first see the guy outside epsilon 9 during a cutaway from the klingon battle, but I don't remember the bit you mention, is it just a practical light?

Again, I've read just about everything on TMP (and interviewed several of the vfx guys) and have never seen anything at all about ship thruster animation even being attempted. And Trumbull had some of the best guys for this (Bob Swarthe, for one), so they could have done something marvelous if they were so inclined, a lot better than anything ILM could have done on the followups even if they subcontracted to VCE like they did for most of the TWOK animation.