posted
Although I agree reverse impulse would be less effective than forward impulse, the acceleration values do not change. Full impulse will always be 1/4 the speed of light. 1/2 impulse will always be 1/8 the speed of light, and so on.
IIRC, we've seem reverse warp in many instances. When Kirk is trying to escape Balok's ship, didn't they go into reverse warp? and didn't the Ent-D go into reverse warp in "Farpoint?" Then again, maybe they didn't.
Also, I would just like to point out, a forcefield to manipulate thrust created by the engines would have to be pretty darn big and very strong. Don't you think it would be a waste of energy?
posted
But we already know that 1/4 impulse is NOT 1/16 of the speed of light. We have seen the movie Enterprise ordered to 1/4 impulse, and CRAWLING at something like 5 m/s.
In fact, there is no on-screen evidence at all that full impulse should equate 0.25c, either. This is just background information from the Tech Manual. Unlike the warp speed charts, which are semi-supported by some episodes because Okuda or Sternbach took the time to work out some travel time references for warp travel and insert them into episode dialogue, the impulse definition from the Tech Manual has never been worked into dialogue.
We do not know how fast the ships travel when at impulse, because the visual effects obviously lie to us - the distances are falsified, so that an engagement at 5,000 km shows the ships actually 500m apart or less, and we can't even tell for sure if some sequences aren't "filmed in slow motion" for aesthetic reasons. All we know is that it is possible to get from Earth out to Jupiter in a couple of hours at impulse speeds (as in TMP), requiring a rather high percentage of c.
However, we can deduce from things like ST3 that the command of "X impulse" does not immediately take the ship to a speed. There is definitely an acceleration time involved, and initially the ship seems to be barely moving.
posted
But we can't judge visually very easily, since a ship seemingly of the refit E's design (namely, the E-A) shot out of Earth's Spacedock at something like 500 m/s (or more than a ship's length per second) in ST6, again when commanded to "1/4 impulse".
All the problems of establishing the speed of an impulse-propelled ship would be removed if one simply accepted the command "X% impulse" as meaning "crank the impulse engines up to X% of their maximum power, helmsman, pretty please". Then the ship could be traveling at any speed between zero and lightspeed when at "X impulse". Zero speed a couple of seconds after the command was given; (near) lightspeed a couple of days, months or years after the command was given, depending on the value of X.
Is there any episode or movie scene where we would see a ship go to a significant fraction of lightspeed under impulse power within just a few seconds? IIRC, all the canonical sources give plenty of time for the ships to accelerate, allowing for accelerations below a thousand gee, just like the TNG TM suggests.
posted
But if we were to accept that, then one ship at full impulse could very well be traveling at .99 c, while another, older ship could be at full impulse and only going .75 c. There is no standard for comparison if we base impulse speed on percent possible output by the impulse engines.
You can't say, "the unknown vessel has just dropped to one-quarter impulse speed." Or, "the Ticonderoga just left the system at full impulse."
posted
But have they ever said that? Or, if they have, has it been about a ship they wouldn't have specs on?
------------------ "I write messages on money. It's my own form of social protest. A letter printed on paper that no one will destroy. Passed indiscriminantly across race, class, and gender lines and written in the blood that keeps the beast alive A quiet little hijacking on the way to the checkout counter. and a federal crime. I hope that someone will find my message one day when they really need it. Like I do." -Rage against the Machine
posted
And did they really want to hear precise estimates of the ship's speed in these cases? Or just the confirmation that the ship is going in direction X at
a) the maximum speed it can muster, signifying aggression/fear, or
b) a leisurely pace signifying innocence/arrogance?
Actually, it would only be a positive thing if the references to impulse-speed maneuvers never gave valid and precise information about speeds. Speeds are purely relative in space, after all (even in the Newtonian sense), and specifying the speed AND the frame of reference might be too slow and tedious for tactical use. Better just ignore the speeds, which don't matter all that much in the end, and let the targeting or navigation computers work them out.
Most times when speed would matter, it would better be expressed as ETA anyway.
posted
I am of the opinion that "full impulse" refers to the full output of the fusion reactors through the rocket nozzle - and has little to do with the speed - they simply shut down the impulse frive when they have achieved the speed required.
Thus, since every class of ship has a different mass, and every class of ship has a different impulse drive configuration, it stands to reason that "full impulse" refers to a different acceleration for each class - and they shut down at the same speed (1/4 c?).
And I concur with Timo - force-field "vectoring plates" (operating much as the vectoring plates on a present-day jet airliner) sounds about right for "reverse impulse" modality.
Cudos Timo and Daniel. I will include force-field generators for this purpose in my deck plans.
Whoever is in charge of the Plans database - please make a note of this.
------------------ Faster than light - no left or right.
Shik
Starship database: completed; History of Starfleet: done; website: probably never
Member # 343
posted
No need, Dave. Look at the Intrepid impulse housings. There's a very clear point at which you see 4 small circles in the front of them. Reverse vents? Probably.
I have the Foundation Imaging 5-views. Big files, but I can always send them. Assuming them made it through the Eating intact.
------------------ "For people with resources, the right events happen. They may look like coincidences, but they arise out of necessity." --T�rk Hviid
posted
I believe the Sovereign class also has some type of reverse vents under the standard impulse engines. But what about other ships, like the Galaxy class?
------------------ Terry: "Carter, Reagan, Bush, Clinton, ...." Max: "And?" Terry: "I forgot." Max: "Come on, Clinton was the fun one, then came the boring one." Terry: "They're all boring."
posted
Given how treknology in general seems to be sliding downhill as time goes by, I wouldn't wonder if forcefield reversers were a technology recently forgotten... The way Starfleet forgot how to manufacture those smaller-than-Nokia-phone phasers that vaporize the victim with one shot, or those automatically raising shields, or FTL phasers.
Or then Starfleet might have opted for lower technology for reasons of robustness and reliability. The E-E does away with many luxuries and high-tech devices already, with flashing video screens instead of the more civilized Okudagrams, and with superclumsy rifles doing a worse job than those early palm-sized type 1 phasers. Perhaps forcefield reversing is another luxury the ship cannot afford?
Or then the ship has forcefield reversers, and these ventral "exhausts" are for some other purpose completely. Or then Starfleet simply found out that a combination of mechanical and forcefield vectoring is actually the best way to go after all.
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