Talk:Impulse drive

Impulse process
This would suggest the process is similar to Warp. Does that mean that they can power nacelles with plasma from the fusiona array, or isn't it powerful enough? -- Redge | Talk 16:30, 17 Aug 2004 (CEST)


 * Please define what you are referring to with the word "This" TOSrules | Talk 16:08, 24 Aug 2004 (PST)

The entire process. But the part that most resembles Warp drive would be:  The accelerated plasma is passed through the driver coils, thereby a subspace field is generated that improves the propulsive effect. -- Redge | Talk 11:43, 25 Aug 2004 (CEST)


 * it's entirely possible. That would play into my theory about Zefram Cochrane. The biggest problem is how could he invent warp drive at Alpha Centauri, when all he could have at most is a DY-500 converter to Impulse. I theorize that maybe his principle was close enough, that the conversion was not to big a deal. I believe he found Lithium Crystals there which is how he made his break through in Warp Drive. The Woden would have been converted after he got back to Earth as an Ore freighter for that Lithium. The Woden proves that early ships did not have the Nacelles for Warp Drive. TOSrules | Talk 15:37, 25 Aug 2004 (PST)

Subspace driver coils
Star Trek: First Contact makes it clear that Cochrane developed the warp drive on Earth. He obviously moved to Alpha Centuari some time after this. The TNG Technical Manual (from which most of the information in this article is derived, despite it being considered less than canon) makes it clear that the warp plasma used to power the field coils in warp nacelles can only be produced by the warp core. The subspace driver coils merely make the impulse engines significantly more efficient. -67.150.72.22 11:22, 18 Jul 2005 (UTC)


 * yah, if you buy the erroneous First Contact movie which fly's in the face of real Star Trek. But this is MA which accepts those kind of facts over TOS. --TOSrules 01:47, 3 Sep 2005 (UTC)


 * I don't think that fusion engines can efficiently support warp, anyway. I know the Phoenix used a nuclear fusion power source, but that was designed for immediate short-term use. I really doubt that deuterium fusion gives much more energy centuries later, and thus creates the need for M/AM power. Maybe why they don't use M/AM for impulse is that it's TOO much energy. Think about putting jet fuel into a car. Sure, it goes fast, but it's murder on the engine. --Zeromaru 01:06, 3 Aug 2005 (UTC)


 * Actually, jet fuel is close to kerosene and would destroy a gas engine to no effect. High octane avgas could be exploited to go faster with the right carb and timing, though.209.43.9.49 17:02, 19 April 2007 (UTC)

How fast?
How fast is quarter-, half- and full-impulse? Does full-impulse equal warp 1? --Perfecto 23:10, 2 Sep 2005 (UTC)


 * As far as I know, it has never been clarified if half impulse means half the speed of light. Although since they do say full impulse at time I suspect it does not mean that at all. After the warp drive was offline in "The Motion Picture" they were continuing at .8 of light speed, these references are the best for knowing the ship's actual speed. --TOSrules 01:47, 3 Sep 2005 (UTC)

I read somewhere (I think some technical manual) that full impulse does not equal light-speed. If I am correct, travelling at warp speed prevents time dilation problems from occuring. If full impulse equaled light-speed, you would encounter the time dilation problem, and nobody wants that of course. Enzo Aquarius 01:51, 3 Sep 2005 (UTC)


 * actually the idea that quarter/half/full directly equates to velocity is rather physics defying. more likely the term impulse is a derivitive of 'specific impulse', a term used to describe the amount of thrust a drive produces. if veiwed in that light, quarter/half/full means running the drive at 1/4th, 1/2, or maximum thrust. the ships would run the drives to accellerate, and then coast on inertia once reaching a desired velocity. we know subspace tricks are probably used to get hyper-efficency out of the drive. the bit about not wanting to travel too closely to lightspeed is valid though, relitivity bites, especially when you get over 50%c. though the use of subspace tricks likely makes it less harsh. -Mithril 15:38, 23 February 2007 (UTC)

Relativity and impulse drive
A starship is stationary in warp drive, at least relativisticly speaking. However, why doesn't a starship incur relativistic time differences when in impulse drive?
 * Basically, the ships travel neither very far nor very fast on impulse because warp is so much faster and safer. — Ŭalabio‽ 08:01, 16 Nov 2005 (UTC)


 * Also, time-dilation effects increase on a curve, asymptotically. If one-quarter impulse power represents one-quarter of the speed of light (which I'm not happy with but that's another matter), the time difference with the rest of the universe at that speed isn't going to be enough to screw around with anybody's lives. You have to be doing .95c or so for the seconds equals hours stuff to really kick in. And it gets more extreme even faster after that. --9er 08:12, 16 Nov 2005 (UTC)

Its actually mentioned somewhere (not sure what the resource is, but DITL.org would be a good place to check) that it is possible to exceed .25c (Full Impulse) - that speed is a Starfleet-enforced restriction on its starships to avoid suffering from such effects. At .25c, the effects of the time dialation are small and, while present, don't affect the ship all that much - ships seldom travel at Impulse speeds anyway: they spend the majority of their time at Warp or in Orbit. --Jace

Numbers
Hope I'm not too late to help...

Full Impulse doesn't equal light speed, as that is Warp 1. I've seen in several reference materials (including the Interactive Encyclopedia) that Full Impulse equals 1/4 c or 167,000,000 mph (Earth to Luna in 5.38 seconds). Here's a [http://www.angelfire.com/nj2/startrek/impulse.html link]. --Squiggyfm


 * I think some people are confused about the nature of impulse; it is fundamentally a thrust based form of propulsion. If the exhaust is leaving the impulse engines at the same speed on all settings of impulse, the difference is one of amount; half impulse is burning twice as much fuel as quarter impulse and produces more thrust because it produces more exhaust. "Quarter", "Half", and "Full" Impulse are most likely measures of acceleration. As there is no wind resistance or other friction in space, only inertia, any ship will continue accelerating until it reaches the maximum velocity allowed by the speed of its exhaust. Unless the exhaust is leaving at different speeds, quarter impulse will eventually reach the same speed as full impulse, it'll just take a lot longer to get there. Fractions of impulse are likely only measures of how fast your accelerating, not how fast you are going. --JCoyote 21:06, 31 October 2006 (UTC)


 * Since nobody else has pointed this out, I feel compelled. "Warp 0.5" does not mean half the speed of light, just as "warp 2" does not mean twice the speed of light.  Warp factors are a logarithmic scale (like decibels).  Therefore, "warp 0.5" would actually be a speed much slower than 0.5c, so all the arguments here regarding relativistic effects at fractional warp speeds are likely moot, as those speeds are actually too slow for any significant relativistic effects to occur.  24.60.246.88 23:11, September 26, 2010 (UTC)


 * That is pointed out in both warp factor and here in the bg section. warp.5 in TMP was something between 0.304 - 0.496 c. I think it is also obvious from this article that full/half/one quarter impulse are much like maximum warp: different speeds with each vessel, according to its capabilities to create thrust. --Pseudohuman 07:14, September 27, 2010 (UTC)

Time Dilation and increase of mass
Has it ever been explained how they circumvent the time dilation and increase of mass that occurs when travelling at speeds closely aproaching the speed of light?
 * Never in canon, although many fans have tried various theories of varying scientific merit... --Jaz talk]] 05:14, 11 February 2006 (UTC)
 * In canon, the inertial mass is decreased with a subspace field created by the driver coil of the impulse engine. --Pseudohuman 07:22, September 27, 2010 (UTC)

Removed from article
I removed the following sentence from the article:


 * The term 'Impulse' is an abbreviation of 'Internally Metered PULSE'.

I heard that somewhere before, but I'm sure it's not from onscreen dialogue. Please decide if it needs to be readded as a background info, and please add a reference! -- Cid Highwind 08:11, 24 May 2006 (UTC)

Why can't impulse engines be used within an atmosphere?
In DS9 episode 2x03, The Siege, Kira tells Dax that she's going to fly their thruster craft into the moon's atmosphere so the attacking Circle (whatever their name is) ships can't use their impulse engines.

I guess I don't understand why impulse engines can't be used in a planet's/moon's atmosphere. Can anybody explain this to me?

-- Ikonomi


 * Well, one idea would be that the impulse engines are nuclear fusion, and therefore have a possibility of radioactive byproducts (yes, fusion does have radiation by-products, just not nearly as bad as fission). The problem is that thrusters also use fusion, or rather microfusion reactors... --OuroborosCobra talk |undefined  14:29, 7 August 2006 (UTC)


 * I don't recall ever seeing anything that resembled a tokamak sitting around in any of the engineering sets, I have to assume that they have some sort of 'clean' reactor by the 22nd, 23rd, and 24th centuries, or at least a more effective way of shielding against radiation.


 * A much easier explanation: Taken from Impulse drive: "impulse was capable of reaching .8 of light speed" .8 of  is about 239,833,966 meters per second. A planet, let's use Earth has a radius of about 6378.1 kilometers, or 6,378,100 meters. That means an object travelling at .8 c would take about 26.5938144 milliseconds to cross a distance the width of a planet, that means a ship running on impulse in an atmosphere would take a tiny fraction of a millisecond before it smashed into the surface of the planet. Similar to the reason that you wouldn't strap a jet engine to a shopping cart and try and steer it around a parking lot--172.166.235.103 14:09, 10 August 2006 (UTC)
 * Actually, you can strap a small jet engine to a shopping cart, and 0.8c would be a maximum speed, presumably you would use lower speeds in space most of the time (if nothing, than just for relativity's sake), and could do the same in atmosphere. --OuroborosCobra talk |undefined  15:43, 10 August 2006 (UTC)
 * The point is, how slow could you make it? When you're talking about something that's measured in terms of tenths of the speed of light? try .1 c, 29,979,245 meters per second, you're still going too fast to actually be able to navigate in an atmosphere without either hitting something, or simply passing the planet by. And yes, you could technically mount a small jet engine onto just about anything, but I'd hope you wouldn't--172.166.235.103 15:49, 10 August 2006 (UTC)
 * Mounting small jet engines on stuff is fun :) --OuroborosCobra talk |undefined  19:50, 11 August 2006 (UTC)

Impulse Manner
Could someone please explain to me, how that drive could possibly let a ship go backward if the impulse engines are only at the back of the ship? An exhaust would mean it could only go forward, and would barely be able (read hardly (not) at all) to break (which contradicts how fast ships stop).

I don't care much about the TM, they are not considered canon by Paramount, and for good reason: they obviously contradict what's on screen. The only way engine mounts only in one direction could make the ship go forward, backward, sideways, up, and down, would be if they generate an energy field around the ship, can generate this field in multiple shapes, and the shape of the field generated is how the ship moves.

Further, if the impulse engines itself generated the subspace field for lowering the ship's mass in normal space; could someone please explain to me, why the Intrepid-class needs to lower its warp nacelles for impulse travel? They wouldn't do anything during impulse speeds, and could just stay up. That only makes any sense, if the subspace field for lowering ship mass, comes from the warp nacelles(, and is more efficiently generated in the lower position, while the up position improves warp travel), which is rather obvious if you ask me.

And yes: the fusion reactors can power the warp coils. How else do you think a Romulan Bird of Prey in "Balance of Terror" could have "simple impulse power" and still move at warp speeds? Obviously it's less energy, and thus the speed would be less than with a warp core, but it's still possible.

Impulse speeds are a lot faster than .25c. During TOS full impulse was probably around .7c. In the movie era just about .8c, and by TNG it was improved to about .92c. Photon torpedoes can go even faster, just about c.

How Fast, part II
On the original Enterprise full impulse power should be 0.5c, as Kirk in the Star Trek:The Motion Picture commands, after leaving Spacedock,

Scott: "Intermix set bridge. Impulse power at your discretion"

Kirk: "Impulse power, Mr. Sulu. Ahead, warp point 5"

The Enterprise is traveling 0.8c only after escaping from the wormhole, which was caused by an antimatter imbalance and required full reverse impulse power to reduce the speed of the Enterprise to below warp speed:

Kirk: "Wormhole. Get us back on impulse power.  Full reverse."

Sulu: "Negative helm control, captain. Going reverse on impulse power"

Uhura: "Subspace frequencies jammed, sir! Wormhole effect!"

Decker: "Negative control from inertial lag will continue for 22.5 seconds before forward velocity slows to sublight speed"

After the Enterprise broke through the warp speed barrier (1.01c), full reverse impulse power was used to slow the ship below the speed of light. Since deceleration was lengthy (22.5 seconds for the impulse engines to slow the ship to below warp (light) speed), the deceleration curve left the Enterprise at 0.8c after breaking out of the antimatter-induced wormhole. It is logical to assume that 0.8c is not a speed that is normally requested by impulse engine power (as per Kirk's request for "Impulse power. Ahead, warp .5") and relativistic time failure.

Although the source is not canon, the Star Trek:The Next Generation Technical Manual (published 1991, Pocket Books) lists the following details, page 78:

"...Today, such time differences [referring to relativistic time failure] can interfere with the requirement for close synchronization with Starfleet Command as well as overall Federation timekeeping schemes. Any extended flight at high relativistic speeds can place mission objectives in jeopardy.  At times when warp propulsion is not available, impulse flight may be unavoidable, but will require lengthy recalibration of onboard computer clock systems even if contact is maintained with Starfleet navigation beacons.  It is for this reason that normal impulse operations are limited to a velocity of 0.25c

Efficiency ratings for impulse and warp engines determine which flight modes will best accomplish mission objectives. Current impulse engine configurations achieve efficiencies approaching 85% when velocities are limited to 0.5c."

Therefore the Technical Manual also confirms that impulse engines can reach, and indeed are efficient in operation, to 0.5c.

Until Mr. Scott acknowledges that the warp engines are available (without a guarantee), no acceleration of the Enterprise is shown above 0.5c --Snake 17:52, 21 December 2006 (UTC)

Note: Again, please inspect scenes from Star Trek:The Motion Picture regarding impulse drive speeds. The Enterprise does not accelerate past "warp .5" (.5c) until after Commander Scott acknowledges that warp speed may be available (but needing more flow simulations on the flow sensors). Until the dialog between Kirk and Scott, no dialog is shown regarding the Enterprise accelerating past warp 0.5.

The only time the Enterprise is shown as doing "warp .8" is after deaccelerating from warp speed using the impulse engines - that is, the Enterprise is coasting, continuing it's forward movement through space, due to inertia at warp .8– Snake 21:05, 16 February 2007 (UTC)


 * They were not "coasting", they were HOLDING at Warp .8. For some unexplained (in universe) reason, drive tech in the Trek Universe is such that ships that lose engine power LOSE speed. (examples numerous).


 * Also, the (lack) of dialogue vis a vis higher warp(decimal) speeds proves nothing in and of itself, esp when we DO have the "Warp .8" reference.Capt Christopher Donovan 10:49, 17 February 2007 (UTC)


 * you mind giving us an actual example of ships losing velocity as they loose impulse power? citing 'examples numerous', besides being poor english, is really no help. i for one, having watched a lot of star trek, cannot remember a single incident where loss of impulse power was followed by anything implying loss of velocity. i can remember quite a few scenes where ships were shown to coast along after their drives were destroyed/disabled. for example, look at the mass fleet actions in the dominion war. quite a few ships had their drives disabled onscreen, and they continued on their last course until destroyed. in a mirror darkly, the andorian ship gets its drive knocked out and it continues on, although it obviously still has manuvering thrusters since it banks away trailing gas. -Mithril 16:19, 27 February 2007 (UTC)


 * you have a good point:


 * Also, the (lack) of dialogue vis a vis higher warp(decimal) speeds proves nothing in and of itself, esp when we DO have the "Warp .8" reference


 * but we do not have a DIRECT quote from a character asking for "warp .8" when ACCELERATING, only after DECELERATING from a higher speed.


 * This is why I claim "0.5c" max impulse power - we have proof of this speed being directly asked for by the commander of the starship from a motionless vehicle situation, but NOT "0.8c" being asked of the impulse drive deck to create, directly.


 * Only, possibly, sustained from deceleration from a higher speed, which may be possible due to the subspace coils integrated with the impulse drive which keeps the mass of the (already) moving vehicle low enough to maintain the noted speed due to inertia.


 * The dialog never notes that the impulse deck is the power maintaining 0.8c.


 * The only dialog we do have notes the impulse deck accelerating to 0.5c after the Captain asks for that speed from a very low speed (thruster) state.-Snake 17:16, 28 February 2007 (UTC)

and if you can reach .5c, physics means you can reach much higher. but after .5c, reletivity starts getting really annoying. so if there is a limit to only .5c, it's a burecratic one, much like the 'warp 5 speedlimit' in TNG. a limit imposed on opertions, not a limit due to physics. the best explantion that explains the evidence seen is that Impulse refers to thrust not velocity, and that the only 'speed limit' at impulse is reletivity. -Mithril 18:33, 28 February 2007 (UTC)


 * the best explantion that explains the evidence seen is that Impulse refers to thrust not velocity, and that the only 'speed limit' at impulse is reletivity.


 * Very much so. Please note that the commander of a ship asks for impulse power, not impulse "speed".  The speed of the vehicle can vary depending upon gravity wells, spacetime distortions, or other phenomena.  The commander of a ship asks for relative power output versus maximum attainable from the impulse system, not a specific speed - i.e. "half impulse", "full impulse".


 * Only in TMP is the commander asking for a specific speed that the impulse engine attain, and therefore it is the only thing we have to go on. At no other time is there quotable dialog which shows impulse equaling to a specific speed, nor does Decker's dialog show that the impulse deck can sustain, over long duration, the quoted speed of 0.8c.  It may be sustainable only for a very (very) short period of time until the impulse engine modifies the vehicle velocity back to a sustainable output vs. relativistic speed.-Snake 19:02, 28 February 2007 (UTC)
 * Let's not forget:
 * KIRK: "Warp drive, Mr. Scott. Ahead Warp 1, Mr. Sulu."
 * SULU: "Accelerating to Warp 1, sir. Warp 0.7, 0.8. Warp 1, sir.
 * The warp 0.5 was made before the ship went to warp, the warp 0.7 was during their acceleration to warp 1. Warp 1 would therefore be the warp threshold. I'm sure Cochrane's speedometer in First Contact could probably support this further. --19:19, 28 February 2007 (UTC)
 * Right. The Enterprise is only shown as accelerating past 0.5c after Scotty acknowledges that the warp system is (barely, not guaranteed) available.  Until the warp engine subsystem is shown as (possibly) available...no acceleration past 0.5c.


 * Same thing with Cochrane - until he says "Engage!" does the acceleration of the ship begin past (relatively) low sublight speeds.


 * Those are the dialogs, as filmed-Snake 20:43, 28 February 2007 (UTC)

in cochrans case, i agree. but i hardly consider .5c as low sublight speed. and deciding to throw out Newton, Einstein and Hawking because of one little segment is a bit much. especially since that one segment is easily fitted into the accelleration paradigm. Kirk could have easily been asking for a specific velocity, with the unspoken order being maximum impulse thrust. why .5c is debateable, but presumably there are regulations about the velocities one can legally reach in a solar system as heavily travelled as Sol. -Mithril 04:29, 1 March 2007 (UTC)
 * Please note that with Cochran's ship, the Phoenix, no speed is shown until he breaks the warp barrier. Until he says "Engage!" the Phoenix is not shown, on screen, to be traveling at any speed faster than a normal rocket launched into space from planetside.


 * Note my belief on this "issue" - I am not attempting to reinterpret Trek science. I am going by exact evidence as filmed.  No more, no less.  For instance,


 * i hardly consider .5c as low sublight speed. and deciding to throw out Newton, Einstein and Hawking because of one little segment is a bit much


 * With Star Trek, none of that science applies because according to standard Newtonion / Einstien physics, a space vehicle should not be able to go faster than the speed of light. Einstein / Newtonion physics do not apply to Star Trek subspace / warp drive physics.  We have seen this time and time again, in the basic operation of the warp drive itself - the warp drive alters mass across the "normal" universe.


 * According to filmed information, the only details we have is that the impulse engines can sustain "warp .5". The warp .8 speed is an aftereffect from the previously generated (but unbalanced) warp field in TMP.  No other evidence of exact speeds have ever been shown.-Snake 15:18, 1 March 2007 (UTC)

actually, the principle of warp drive is the alcubier metric, which is an outgrowth of einsteinian physics. because nothing can exceed the speed of light in 'standard' space time, it is possible to create a 'non-standard' spacetime in which you can. this loophole has been recognized in reality for some time. however, the impulse drive is not the warpdrive, it's a fusion drive, and operates within standard space time, meaning that newtonian laws of physics and the einsteinian augmentations there of do apply. the use of subspace derived effects to enhance the efficency of the drive des not change the physics. because impulse drive does not operate on the bending of space for propulsive force, the newtonian laws of motion still apply. now, if the warp drive were being used for sublight propulsion this would be a different matter. -Mithril 19:58, 1 March 2007 (UTC)
 * According to Einstein's principle, the Constitution class Enterprise, (approx. 172,368,000 kg), would require:


 * 1.5492e+25 joules


 * or


 * 1.1426e+25 foot-pounds,


 * that's 11,422,600,000,000,000,000,000,000 foot-pounds, or


 * 3.7026e+12 kilotons of TNT
 * 3.7026e+9 megatons of TNT


 * or 3,702,600,000,000,000 - 3,700 billion pounds of equivalent explosive force


 * to accelerate to 0.5c, as per the convenient calculator: http://www.1728.com/einstein.htm


 * As per the TNG:TRM, the impulse engines do use subspace warp coils - and therefore warp theory - to alter the spacetime continuum when under impulse power - please see TRM page 77.


 * The impulse engines do not create, without using subspace field dynamics, the power necessary to accelerate a starship to warp .5 within the times shown as necessary during a mission.


 * For example:


 * according to the TRM the Enterprise E impulse deck outputs 12e+12 megajoules, or 3.209795e+23 kWh, of power. This is not nearly enough to accelerate the vehicle to the speeds vs. time necessary, as (for the Enterprise E, 4 million metric tonnes) you would need 3.5950e+26 joules (35.95e+17 megajoules) of energy...which the impulse deck is not rated for (if I did my conversions correctly).  As shown, the impulse deck is only rated for a fraction of the power necessary if Einstein relativity physics were in full effect.


 * Einstein physics only partly apply to impulse drive as the subspace coils modify the local spacetime, as per TRM.-Snake 22:34, 1 March 2007 (UTC)

and IIRC in the techmanual, the subspace coils used in impulse drives are only for mass dampening effects, as seen in DS9. not propulsion itself. so the laws of motion are still functional, but the ship needs a weaker drive to acheive a desired thrust. once under thrust, the only limit on velocity is relitivity. there is no physical law that limits a ship to .5c max. as i stated before, there might be govermental laws, but thats a different story. look at DS9. they used the deflectors to generate a subspace feild that reduced the mass of the station so that a few weak thrusters could move it to a new orbit. this is how the impulse drive is listed as working, only less jury-rigged. if the coils use warp feilds to move the ship directly, as you've indirectly suggested, why bother with a fusion drive at all? why not just run the coils directly off the warpcore and dispense with the fusion drive entirely? -Mithril 23:58, 1 March 2007 (UTC)
 * "and IIRC in the techmanual, the subspace coils used in impulse drives are only for mass dampening effects, as seen in DS9."


 * No.


 * Star Trek: The Next Generation Technical Manual, page 75:
 * "During normal docked operations the main impulse engine is the active device, providing the necessary thrust for the interplanetary and sublight interstellar flight. High impulse operations, specifically velocities above 0.75c, may require added power from the Saucer Module engines.  These operations, while acceptable options during some missions, are often avoided due to relativistic considerations and their inherent time-based difficulties (See: 6.2).


 * During the early definition phase of the Ambassador class, it was determined that the combined vehicle mass of the prototype NX-10521 could reach at least 3.71 million metric tons. The propolsive force available from the highest specific-impulse (I/sp) fusion engines available or projected fell far short of being able to achieve the 10km/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.  The driver coil was already into computer simulation trials during the Ambassador class engineering phase and it 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.


 * Experimental results with exhaust products temporarily accelerated beyond lightspeed yielded disappointing results, due to the lack of return force coupling to the engine frame. The work in this area is continuing, however, in an effort to increase powerplant performance for future starship classes."


 * Page 77:


 * "Energy from the accelerated plasma, when driven through the toroids, create the necessary combined field effect that (1) reduces the apparent mass of the spacecraft at its inner surface, and (2) facilitates the slippage of the continuum past the spacecraft at its outer surface"


 * ST:TNG Technical Manual, copyright 1991 Paramount Pictures, published by Pocket Books, NY.


 * So by 2350 the impulse engine subsystem can sustain speeds to at least 0.75c...but it is not recommended, if at all possible, due to relativistic failures. As noted on page 78, and suggested by you, normal impulse operations are limited - by "bureaucratic" rules - to 0.25c with impulse engines achieving "efficiencies approaching 85% when velocities are limited to 0.5c".


 * Beyond that point efficiency falls rapidly - and this is TNG era, the 24th century.


 * The impulse engines in TOS time, 23rd century, should therefore be less powerful and less efficient, for as noted the Enterprise E would require 2 impulse drive decks - the Main and the Saucer - to be operated simultaneously in order to reach the quoted 0.75c speeds. And, as [implied by] the Technical Manual, impulse engines prior to those installed in the Galaxy class starships did not have integral space-time drive coils as part of the subassembly.


 * The reason that the warp subsystem is not used to manuever the ship at sublight speeds is efficiency - it is very inefficient of drive plasma (matter / antimatter supplies) to operate the warp core and nacelles at sublight speeds. It is far more efficient of limited fuel supplies to have independent drive subsystems.-Snake 02:48, 2 March 2007 (UTC)

so your arguement is that to explain TMP, the enterprise is equipped with a system not in use until 70 years later? one that does not explicitly state that it works as direct propulsion, or that it ignores the laws of motion? as for efficency, having multiple reactors is highly inefficent, expecially with the energy density of antimatter. for the same mass as the bulky fusion plants and their fuel you'd be able to carry a lot of antimatter for the warp core, of which you'd only need to little at a time given the rates trek ships seem to use antimatter at full warp.
 * Hey guys, I hate to jump in here, but this discussion is getting very long and has gotten off topic. All that is supposed to be discussed here is what can go in the article, and this has delved into personal speculation that does not belong in the article. In addition, the topic you guys were talking about (AFAIK) was whether the impulse top speed was .5c or .8c, and you've deviated tremendously. If you want to keep talking about speculation as to things like the efficiency of impulse vs. warp drive at sublight, or having so many reactors, etc., then please take it somewhere like TrekBBS, as MA is not the place for this discussion anymore. --OuroborosCobra talk 15:22, 2 March 2007 (UTC)
 * Yes, thank you. I thought I was staying on topic by showing (a) as filmed dialog and (b) the theory of impulse drive operations, based upon the only "known" source - the TNG Tech Manual - which shows no space-time coils until Ambassador therefore Constitution Enterprise would not have those features...and must operate at lower speeds.  Please note that I have not re-altered the Wiki quoted speed - if others feel there is room for debate, it is not my place to override it.


 * Please feel free to delete all my comments on this Talk page if you desire it.


 * Again, apologies.-Snake 16:19, 2 March 2007 (UTC)

perhaps a section with the techmanual speed info should be added, along with with something like Alternately, the terms full, half, and quarter impulse could mean portions of the total thrust, and thus accelleration, that the impulse drive can produce. either way, the ship would probably reach .8c easily, but the inertia based possibility should be mentioned, unlike currently. as for the debate, deletion would probably just cause it to be started again by other people, so perhaps it could be moved to the Ten Forward Forum? - Mithril 22:35, 2 March 2007 (UTC)

Random thought
Perhaps "full impulse" is the maximum speed a ship can travel at before warp drive becomes more efficient to use. That'd explain a number of TOS comments, and sort of reconcile them with the later series' comments of it always seeming to be lower (due to improved technology over time). In particular, the Romulan reference makes more sense. I know it's more useless speculation, but it's an idea I've had in my head for a while that I've been meaning to mention here. - MK (t/c) 10:56, June 3, 2010 (UTC)


 * As stated elsewhere on this page, posts on article talk pages need to be about changing the article, and are not for merely posting our speculations or general discussion of the subject.--31dot 11:00, June 3, 2010 (UTC)


 * * sigh*... The entire talk page is about discussion of this topic. It's Star Trek, this is what we do. I now remember why I became inactive here :/ - MK (t/c) 11:02, June 3, 2010 (UTC)


 * And most of those posts are very old and probably before that policy was developed. This is not a chat room- we are here to write the encyclopedia.  You can post your own personal statements on your user page or user talk page.  My intention is not to drive you away- but we do not want every talk page to look like this one.  That's not why we're here.--31dot 11:05, June 3, 2010 (UTC)


 * The policy has been there for far longer; it comes from Wikipedia which was the trend setter I assume. I understand its purpose, as I've been a "wiki" guy for quite some time. I just don't think it's something people should jump on unless it results in the violation of other policies, such as flaming or starting an edit war. Having ideas is how these wikis start in the first place; Trek fans especially have a lot of speculation that doesn't belong in articles, so I just wanted to throw it out there. - MK (t/c) 11:13, June 3, 2010 (UTC)

Impulse in Sub-orbit?
Has there ever been any mention of impulse drive being used in an atmosphere? If not, it would imply it's not only bajoran interceptors who cant use impulse in sub-orbit.Thomsons Gazelle (talk) 23:17, January 8, 2013 (UTC)