Excelsior class design flaw

[Xerxes1979]

I noticed that the refit Excelsiors position their additional impulse engines in a configuration that would exhaust waste gases directly onto the warp nacelles and strut.

Wouldn't this be extremely bad for the ship? To my knowledge no other ship has this fault.

 

[Timo]

1) We don't know if those are impulse engines.
2) We don't know if impulse engines exhaust waste gases directly aft.
3) The Steamrunner class also has red things that are supposed to be the ship's impulse engines but that would blast right into the ship's structures (the aft pylons) if a rocket flame emerged from them and pointed directly aft. the Prometheus class comes close to having that, too. But as said, we have never heard of an impulse engine producing a rocket flame.

Timo Saloniemi

 

[Saquist]

Excelsior's true flaw is it's PTC running along the surface of the hull.

 

[Dukhat]

Do impulse engines exhaust waste gas? For that matter, do warp engines?

 

[Xerxes1979]

Do impulse engines exhaust waste gas? For that matter, do warp engines?

Star Trek VI heavily implies they do emit waste gas.

I don't see how impulse can be argued to be anything other than a newtonian based mass reaction method of propulsion. If it was warp based you wouldn't need a second type of engine.

We have chemical, ion and nuclear propulsion today. The United States is unfornately too broke and in decline to actually go anywhere with it.

 

[Timo]

We know from ST6 that the impulse engine acts like a tailpipe, yes. Curiously, we often hear of ships leaving a "warp trail" that can be followed, but there's no comparable "impulse trail" to help our heroes track the villains... This suggests that the emissions from the tailpipe aren't necessarily continuous, but take the form of occasional dumps. In which case they probably don't serve any major propulsive function, because starships at impulse would have little reason to shut down the engines at any point. Coasting on inertia would just mean that you reach your destination more slowly, which may be sensible with today's primitive rocket engines but makes no sense when your engines have enough fuel for years of operations.

The impulse drive can be just about any type of propulsion we can or cannot imagine. Today, spaceplanes are being planned that have two different types of Newtonian thrust engines - turbojets/turbofans, and rockets. Tomorrow, starships might be equipped with two different types of engines based on subspace manipulation, only one gives them FTL and the other STL mobility.

Timo Saloniemi

 

[Saquist]

Frankly I'm not sure.

My theory was based on Impulse engines using coils to "surf" on Fusion Implosion Displacement Waves and the by products were energetic Ions as we saw in Relics.

 

[VixenLieutenant]

I'm not sure either.

 

[Forbin]

Forgive me, but, you're just noticing this now?

 

[Crazy Eddie]

Do impulse engines exhaust waste gas? For that matter, do warp engines?

Star Trek VI heavily implies they do emit waste gas.

I don't see how impulse can be argued to be anything other than a newtonian based mass reaction method of propulsion. If it was warp based you wouldn't need a second type of engine.

Hell, I've been saying this for years. If warp drive or a warp-like system were capable of precisely controlled sublight velocities, they would just use the warp drives for that; if you want to move very slowly you could just order "warp point one" or something, and any slower velocities would be "thrusters."

Instead, they're using impulse engines to travel at velocities between 60 and 200mph. Just doesn't seem like the kind of thing that would really require a subspace field coil, and even if it did, there is ZERO reason to have it hooked up to a separate power source since you can much more easily siphon off a trickle of energy from the warp core.

 

[Herkimer Jitty]

I guess it all depends on how you take the "full reverse" and "full stop" stuff, as well as the banks and swooshes that ships do. One could try to rationalize them into fitting a newtonian drive type model, rationalize them into fitting a non-newtonian drive, or ignore the VFX and pretend the ship jets around on its RCS quads and turns around for braking maneuvers.

If the show was nothing but dialogue, I don't think this would be as divided a debate.

 

[Santaman]

I always believed that the impulse exhaust was only there to get rid of the waste product of the fusion reactors, as for the impulse drive itself, since it can also be powered by the warp drive (like in TMP) I think they're a specialised sub space coil drive, and I still think its stupid looking to aim the impulse exhaust at any part of the ship's superstructure...

 

[Forbin]

Supposedly they were supposed to be hangar decks on the B, but some suit told the effects guys to make them into kewl glowy engine thingies. They make SOME sense as hangars, though an exiting shuttle would have to be careful not to faceplant into the bussards.

 

[SchwEnt]

Getting IN to a hangar bay at that location would be even worse. Squeeze in between the hangar and the front of the nacelle like that? Why? It's ridiculous, for hangars or impulse engines.

Especially silly since just raising the nacelle pylons a few meters above the height of the primary hull would solve the damn problem.

 

[Timo]

If the things are big reactors for the impulse drive, then placing them close to the actual rocketlike parts of the preexisting impulse drive is probably very sensible.

Whether the exhausts of an impulse power system would be used in a rocketlike manner even if impulse drive itself worked on subspace coils... It's not unheard of, in terms of real world analogies. Several propeller aircraft piston engines were built so that their exhaust gases added to the overall thrust - almost negligibly, to be sure, but there was no reason not to twist their tailpipes so that this little advantage could be gained. Many (although not all) turboprops follow suit in using the exhaust of the turbine in a propulsive manner even though the propeller is the thing.

IMHO, it's quite possible that Starfleet engineers decided to make some use of the exhaust gases from the impulse engine tailpipe in some starship designs, but not in all of them.

OTOH, if the Bussard scoops in front of the nacelles are really there for the purpose of collecting interstellar gas (although this has never been indicated onscreen), then we know Starfleet has the means of twisting the flowpaths of gas in vacuum without visible means; otherwise, said gas couldn't reach the often obscured 'scoops. It then more or less follows that an impulse engine could belch out a rocketlike jet from any arbitrary location, in any arbitrary direction, and this invisible tech (forcefields, I guess) would then manipulate the jet to create proper Newtonian thrust in the desired direction.

Timo Saloniemi

 

[Forbin]

Getting IN to a hangar bay at that location would be even worse. Squeeze in between the hangar and the front of the nacelle like that? Why? It's ridiculous, for hangars or impulse engines.

Especially silly since just raising the nacelle pylons a few meters above the height of the primary hull would solve the damn problem.

I moved them outward in this kitbash:
http://www.inpayne.com/models/kitbash/trekpage_kirov.html
So the impulse exhaust (if any) fires between the nacelles.

 

[Forbin]

Double post
Double post

 

[publiusr]

I always thought that impulse exhaust would still be rich and the nacelles took some flow in as a re-breather. Figure that this class ship hangs out near steep gravity wells where a larger impulse deck is needed to pull away.

 

[SWHouston]

"Everything's got to have a Tail Pipe, right"

 

[Bry_Sinclair]

One major design flaw I've seen on plans for the Excelsior-Class is that the ship has 4 forward torpedo launchers, two either side of the deflector dish and then two on the neck between the saucer and the drive sections.

The two upper launchers apparantly can't fire forward, as there is no clear line-of-sight from them. Any torpedoes fired from there would crash into the sensor dome.

I love the Excelsior-Class, so on the Trident, I've ignored these upper launchers and just established that the ship has two launchers forward and two aft.

-Bry