Impulse Drive, Therories on how it works?

[Tenacity]

I am surprised that the highly advanced First Fed ship was at sublight speeds and not towing at warp speed

The whole thing was a test, it wasn't ever a matter of taking the TOS Enterprise to a destination.

We've also seen how ships can travel in REVERSE at both impulse and Warp speeds

The FJ blueprints say that the impulse engines can move the ship in reverse though the use of the shields redirecting the thrust.

Impulse engines have no visual exhaust that we've really seen and are highly efficient.

Spock (TUC): Gas. ...Gas, Captain. Under impulse power she expends fuel like any other vessel.
Uhura: Well, what about all that equipment we're carrying to catalogue gaseous anomalies? ...Well, the thing's got to have a tail pipe.

We don't see it, but apparently it's there.

 

[Timo]

...Yet it is analogous to a tailpipe, which is not a propulsive component in most engines.

In a jet engine, it might be - but nobody calls it a "tailpipe" there. In a propeller plane, car or boat, it burps out foul gases even when the vehicle is not moving - and this seems to be true of starships, too, the E-D engine glowing red even at idle.

So the tailpipe exhaust is unlikely to be used for propulsion, and vectoring it is likely to be unnecessary. Although not impossible - and some piston-engined propeller planes indeed use their exhaust to provide (a minimal amount of) extra thrust. Most don't, though, and some even vent their exhaust forward.

Timo Saloniemi

 

[Tenacity]

In a jet engine, it might be - but nobody calls it a "tailpipe"

Yah, people pretty much do.

 

[Mytran]

Yah, people pretty much do.

Hey. I've learned something today...
https://simpleflying.com/tailpipe-fire-explained/

 

[Deks]

Yah, people pretty much do.

And yet we've seen that the movies and shows only use modern-day terminology to 'dumb down' the explanation behind how certain technology works - this should by no means be used as a way to 'accurately' describe an inner working of highly advanced technology... only a crude approximation.

Impulse engines usually leave an Ion trail behind them... but this could easily be a simple byproduct of how the technology is used.
Otherwise, it seems that both Impulse and Warp propulsion are predominantly achieved via field/energy manipulation... and virtually no exhaust to speak of - they do leave residual trails behind yes, but as I said, this has less to do with exhaust and more of a byproduct of field/energy manipulation.
Only thrusters seem to be using exhaust as viable means of propulsion.

 

[Henoch]

Only thrusters seem to be using exhaust as viable means of propulsion.

The TOS-E got by just fine without any thrusters. They used impulse engines for moving around (I think the word "thruster" was never use about the TOS-E).

 

[Mytran]

Ships like the Enterprise could manoeuvre OK using only warp drive, according to dialogue in The Ultimate Computer

That being the case, I'm sure that Impulse Power would have been perfectly fine for most other routine manoeuvres

 

[Deks]

The TOS-E got by just fine without any thrusters. They used impulse engines for moving around (I think the word "thruster" was never use about the TOS-E).

Even if the word "thruster" was never used, that doesn't mean that thrusters didn't exist on the original Constitution class (in fact, from Star Trek Enterprise: In the Mirror Darkly, Part 2, thrusters are referenced on the USS Defiant - a Constitution class ship which was caught in a Tholian web in TOS and ended up in the Mirror Universe about 100 years in the past).

The lack of use of thrusters from Enterprise in TOS is another story (but I don't know whether we can say they were never used) - and its easily explained that circumstances/stories never deemed it necessary to USE thrusters as means of propulsion in TOS (at least not during the actual episodes).

The primary means of sublight propulsion are impulse engines... though thrusters do appear to be used when entering/exiting space-docks and drydocks (requiring very low speeds for approach and departure).

I would imagine though that Impulse engines can also be used to propel a ship at very low speeds... but they MAY have a 'starting point' much like Warp drive (which is Warp 1 - or faster than light).
So, for Impulse drive, the lowest recorded speed could be say 500 - 1000 km/s (and highest at least 75 000km/s... but much more than this was also mentioned/inferred as the uppermost range for Impulse speeds too).

The upper-most speed for a ship using thrusters could be several hundreds of km per hour (maybe 500 km/h) - but they are predominantly used for maneuvering (and use of subspace fields which lower a ship's mass allow for fighter-like maneuvering of even huge ships).

 

[Deks]

Ships like the Enterprise could manoeuvre OK using only warp drive, according to dialogue in The Ultimate Computer

That being the case, I'm sure that Impulse Power would have been perfectly fine for most other routine manoeuvres

Trek demonstrated on multiple occasions that Impulse and even FTL engines don't really function in a classical capacity, but rather rely on field manipulation that those engines generate (which would allow omnidirectional maneuvering/traveling depending on the circumstances).

A low-level subspace field seems to be generated by starships to lower their mass which allows them to maneuver like fighters and also achieve very high speeds under only thrusters.

The Warp nacelles themselves produce a Warp field which is then controlled by the crew to travel at FTL speeds (and a whole other things).
Impulse engines could be the same... they generate a field around the ship which is controlled by the crew in conjunction with other technologies to achieve very high sublight speeds (one quarter light speed at least, and at least and maybe 3x as much at absolute highest) while avoiding relativistic effects.

We're basically talking about field generators and manipulation of those fields... so the 'relative position' of the engines/generators themselves doesn't technically matter.

 

[Henoch]

We're basically talking about field generators and manipulation of those fields... so the 'relative position' of the engines/generators themselves doesn't technically matter.

I like your thoughts on field generators associated with the impulse drive system. They may not be slow enough or possibly interfere with other close by space structures like inside space docks, so, low powered maneuvering "thrusters" is regulation. During TOS, the Enterprise was never that close nor inside any space structures, so, we never needed to hear about thrusters. In The Undiscovered Country, Kirk used impulse engines to exit the space dock which was shocking to Valeris:

KIRK: Awaiting port gates from this mark.
SPACEDOCK VOICE: All lines cleared.
VALERIS: Aft thrusters.
KIRK: Thank you. Lieutenant, one-quarter impulse power.
VALERIS: Captain, may I remind you that regulations specify thrusters only while in Spacedock?
SPOCK: Hm. Hm.
McCOY (OC): Jim?
KIRK: You heard the order, Lieutenant.
VALERIS: Aye sir.

I assume that the regulations within space docks have not changed for sometime in the TOS era. I'm a convert.

 

[Mytran]

Given all the impossible things an Impulse Drive does (like making the ship reverse) and odd locations it's found in on various starships (usually not centre of mass), it only really makes sense for the ID to be a field based device.

They may not be slow enough or possibly interfere with other close by space structures like inside space docks, so, low powered maneuvering "thrusters" is regulation. During TOS, the Enterprise was never that close nor inside any space structures, so, we never needed to hear about thrusters.

I'll buy that too! Space stations were places that you beamed over to in TOS, not docked with.
Perhaps the thrusters stayed behind hull plating, to keep them safe and space-dust free for the rare times they were needed?

 

[Deks]

I like your thoughts on field generators associated with the impulse drive system. They may not be slow enough or possibly interfere with other close by space structures like inside space docks, so, low powered maneuvering "thrusters" is regulation. During TOS, the Enterprise was never that close nor inside any space structures, so, we never needed to hear about thrusters. In The Undiscovered Country, Kirk used impulse engines to exit the space dock which was shocking to Valeris:

I assume that the regulations within space docks have not changed for sometime in the TOS era. I'm a convert.

Kirk using Impulse engines to exit a space dock was a bit stupid... the ship would basically cross 500 to 1000 km in 1 second (at least) and this I think could be dangerous when exiting a starbase due to potential workbees and shuttles going about their business - albeit, all of that would probably also be handled by the computer/automation to avoid/minimize collisions... still, suddenly engaging impulse engines in a space dock? Nope.
But at I said, its possible that they were drummed down to 'thruster-like speed'.

Given all the impossible things an Impulse Drive does (like making the ship reverse) and odd locations it's found in on various starships (usually not centre of mass), it only really makes sense for the ID to be a field based device.
I'll buy that too! Space stations were places that you beamed over to in TOS, not docked with.
Perhaps the thrusters stayed behind hull plating, to keep them safe and space-dust free for the rare times they were needed?

Well, Trek is quite big on starships generating all kinds of fields and doing things through fine manipulation/control of those fields.
So, yes, it does make sense that Impulse drive and Warp drive are field based generators which propel the ship at very high sublight or FTL speeds, and can do so in almost any direction (we even have evidence of Warp drive being able to propel a ship in REVERSE in TOS) because you are manipulating the whole field around the ship and aren't relying on 'classical exhaust' like real life engines do to propel you in a specific direction.

It might be that starship captains tend to PREFER traveling 'forward' by also having the ship FACE in that direction... but otherwise, they COULD propel a ship sideways (for all we know) if such a situation arose.

Space stations are usually places crews would beam over yes... but we have seen them more extensively using space-docks to conduct repairs, maintenance, upgrades and go for shore-leave... predominantly in the movies and TNG (when the budget was bigger).

 

[Mytran]

But at I said, its possible that they were drummed down to 'thruster-like speed'.

Maybe the field takes a moment to get to max speed when first switched on?

(when the BUDGET was bigger).

oooh, you had to go there! Bob Justman would like a word...

 

[Deks]

Maybe the field takes a moment to get to max speed when first switched on?

Perhaps, but the Enterprise took way more than a moment to exit the space-dock.
Its possible the con officer decided to reduce impulse speed to thruster level for safety reasons (so, technically, they'd be using Impulse power yes, but not to its fullest).

oooh, you had to go there! Bob Justman would like a word...

Not sure I get the reference.
The budget referred to real world.
We know a lot of things weren't shown in TOS due to budget constraints... this of course changed when TNG aired (and also, technology improved quite a bit by then).

 

[Henoch]

Its possible the con officer decided to reduce impulse speed to thruster level for safety reasons (so, technically, they'd be using Impulse power yes, but not to its fullest).

Kirk ordered 1/4 impulse power. I doubt Valeris (on helm) didn't follow those orders after Kirk repeated the order again, nor later comment on it that she always wanted to do that. No, Kirk got 1/4 impulse power. The ship was stationary, so, even with impulse thrust, she would still need to accelerate up to 1/4 impulse speed, so, the first moments in spacedock would show the ship relatively slower than whatever 1/4 impulse is.

 

[Timo]

Thankfully, we don't have to think that "impulse" would be any particular "speed". Rather, ever since that TOS classic, impulse has been directly equated with "power", so we could well treat it as a throttle setting.

This gives us maximum freedom: different ships would move very differently at 1/4 throttle, and would respond to different "sea states" and degrees of damage, too. But it's not quite enough, alas: we additionally have to assume that the throttle settings are not linear, or else the ship that crawls out of Spacedock at 1/4 throttle could never make it to another planet the way she's seen making it, even at four times that throttle.

Either that, or then acceleration initially takes a certain amount of time basically regardless of throttle setting, and the ship crawls at half a gee even on those settings that allow it to eventually move at 900 gees between planets. That is, the propeller is churning and cavitating like mad before it finally "bites" and shoots the boat forward through the water.

Timo Saloniemi

 

[Henoch]

That is, the propeller is churning and cavitating like mad before it finally "bites" and shoots the boat forward through the water.

Comparison metaphors: Impulse power to naval ship operations (STL) and Warp power to hypersonic jet planes (high FLT). Occasionally, the ship can act as a hydrofoil boat (obtaining low FLT) by lowering its mass with a gravity field or something, but this burns a lot of Impulse fuel.

 

[Mytran]

Not sure I get the reference.
The budget referred to real world.
We know a lot of things weren't shown in TOS due to budget constraints... this of course changed when TNG aired (and also, technology improved quite a bit by then).

No worries, it wasn't terribly funny!
Just a vague reference to how Justman was constantly keeping a lid on expensive plot ideas.

I'm sure TOS would have loved to show a docking sequence if they could have afforded it

 

[Timo]

Comparison metaphors: Impulse power to naval ship operations (STL) and Warp power to hypersonic jet planes (high FLT). Occasionally, the ship can act as a hydrofoil boat (obtaining low FLT) by lowering its mass with a gravity field or something, but this burns a lot of Impulse fuel.

...Heck, wallowing to match a damaged fellow starship capable of 1/3 impulse already burns a lot of impulse fuel in "Doomsday Machine"! And interplanetary flight at mere impulse is supposed to be basically unheard of in "Elaan". Might be the technology either is downright ferocious in its appetite, or then is essentially incompatible with insystem use even if it works just fine in deep space combat.

We then are left wondering why Janeway out of all captains would spend so much time at impulse if the way to save fuel were to remain at warp.

Timo Saloniemi

 

[Mytran]

In The Doomsday Machine the main drive was down though, meaning ALL they had was impulse fuel reserves. This suggests that the warp engines usually assist the Impulse Engines in some manner, perhaps even generating fuel for them?