^^Well, first of all, a lot of starships have violated the impulse-engine placement rules you describe, so we have to assume there's something more than Newtonian thrust at work.
There's actually an argument in favor of that, but it's one that was disregarded/countered by the TNG-and-post Trek canon. Remember that in Star Trek, the Romulan interstellar craft were supposedly "impulse-only." Remember that the Enterprise made it from the barrier to Delta Vega without warp drive. It was always implied that impulse was actually capable of faster-than-light propulsion. In "The Cage," Jose... whatever his name was, the navigator... told the illusory rescuees that "You won't believe how fast you can get back! The time barrier has been broken, why our new ships...." All these together sort of implied that impulse was a relatively slow, but definitely supra-light-capable, propulsion system.
Second, the TNG Tech Manual made it pretty clear that impulse engines actually use a subwarp spatial distortion as their mechanism of propulsion, because there's no way any mere rocket thrust could give something as massive as a Starfleet heavy cruiser the kinds of accelerations we've seen.
Not true. Here's what it actually says. From page 75...
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 propulsive force availble from the highest specific-impulse (I-sub-sp) fusion engines available or projected fell far short of being able to achieve the 10 km/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 vehcile 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 product accellerated 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 attempt to increase powerplant performance for future starship types.
And from page 76,
The main impulse engine (MIE) is located on Deck 23 and thrusts along the centerline of the docked spacecraft. During separated flight, the engine thrust vectors are adjusted slightly in the +Y direction; that is, pointed slightly up from center to allow for proper center-of-mass motions (See: 6.3). The Saucer Module impulse engines are located on Deck 10 of the vehicle XZ plane and thrust parallel to the vehicle centerline.
So, it's established that impulse engines are Newtonian, and that the FIRST TIME that "impulse engines" used anything other than convention Newtonian thrust was with the Ambassador development project, and the use of the added driver coil was to super-accelerate the exhaust products to superluminal velocities.
You could argue that changes have occurred between the time of this writing (in the fiction, I mean) and the launch of Titan, or that it uses something new and different from classical impulse. (And "impulse" is BY DEFINITION A NEWTONIAN TERM, by the way, used to describe any "equal and opposite reaction") A new propulsion system could exist... after all, this was supposedly written at the time of the launch of Enterprise D, a bit more than a decade earlier).
(By comparison, it takes an oil tanker something like hours to slow to a stop, and it's travelling at an infinitesimal fraction of starship speeds.)
Yes, but you're comparing a diesel engine to what is essentially a directed hydrogen bomb. The thrust output of an oil tanker is not based upon needing to accelerate fast. By comparison, an aircraft carrier, which is at least as massive, can accelerate many times faster. And in those cases, we're talking about dealing with very small power reserves compared to what you get from a fusion reactor (even the fission-based nuclear carriers we currently have are designed for energy efficiency, not for high performance in the turns!)
Fusion propulsion is the most reasonable, practical interstellar propulsion system on the boards today. And if you can come up with a way of safely directing the output of a fusion reaction, you can get some pretty impressive energy output, purely directed to Newtonian thrust.
So it stands to reason that distortion could be altered to vector the resultant thrust in ways unavailable to a rocket thruster.
While a new system might be possible, one of the key elements in any design is what we like to call "the KISS principle." KISS stands for "keep it simple, stupid!" Or, tranlated into "Scotty-ese," you could say "The more complicated the plumbing, the easier it is to stop up the drain."
Basically, we have a very clear understanding of the laws of Newtonian physics. We don't know for a fact that supraluminal propulsion isn't possible, based upon some element of physics we don't know yet. ALL REAL PHYSICAL OBJECTS obey the newtonian laws, and while it might in theory be possible to circumvent those laws, it's hard to imagine WHY you would circumvent them if it wasn't necessary.
Yes, a few Trek ships have violated this, but not by any means have MOST of them done so. Only a few have been really eggregious about flaunting the known laws of physics.
So, while it IS only fiction, and it can be done "anyway that looks cool," if it's possible to make be closer to reality, WITHOUT DAMAGING THE "COOLNESS FACTOR," why would you not want to do that? We're talking a VERY minor tweak to the design, and it will work with both "as yet undiscovered" physical laws and "already well-understood" physical laws. The ship will look almost identical with those minor tweaks, after all, and technical people (like me but also like all the many scientists, engineers, advanced students, etc) who are fans will not be "jarred" out of enjoying the entertainment by seeing stuff that just screams out "THIS IS IMPOSSIBLE." That's why I can't make myself watch Armageddon all the way through without yelling at the screen... good storyline, fun characters, LIV TYLER... a lot of nice stuff there... but seeing the Russian station in that movie puts most technical types into appoplexy!
Sorry, I thought the entire point of something like this was for feedback, which also means people saying they don't like it, and hopefully being more effective by going into detailed analysis as to why they don't like it.
