Engine Room(s) on the TOS Enterprise (revisited)

[Henoch]

FWIW, Memory Alpha seems to believe that that the dilithium crystal converter assembly (DCCA) is just the part that holds the crystal and is apparently analogous to the 24th century dilithium articulation frame.

I'm not sure exactly how they reached that conclusion, but that's what I've always thought from "Elaan." It's what Scotty is looking at, but I suppose it could be the whole doodad (syncrotron unit).

https://memory-alpha.fandom.com/wiki/Dilithium_crystal_converter_assembly
https://memory-alpha.fandom.com/wiki/Dilithium_articulation_frame

Okay people, we have to call it something? My thinking (I apologize for all the acronyms):

1. The Dilithium Crystals (DC) generate ship power from the M/AM reaction (don't know how, but they are work together to provide main/warp power). When the DC are associated with the M/AM reaction, they "convert" the M/AM energy into power for the ship probably by charging up or "energizing" the ship's EPS.
2. The M/AM reaction takes place in the M/AM reaction chamber. (TWS) There is an intermix temperature and intermix formula (probably for the M/AM reaction itself). (TCM, TNT)
3. "Doodad" on the engine room floor added. Season 2 had a box with dark blue heat exchanger fins on top. https://i.ibb.co/1vrpByD/doomsdaymachine-ER.jpg (Enterprise's box is on the console side. Maybe the DC are inside of it but need more work to remove them or removed from below.) Note that one of the bronze balls is blown, so, too much power/heat was inside of it. Or it got fried from an external electrical/plasma arc from the vertical power shaft (shown on right of it) when it blew first, or visa versa. Scott moved this line out of the Enterprise's engine room in Season 1 because it was too vulnerable to external damage (TEW). No dilithium mentioned, yet.
4. In Season 3, the Dilithium Crystals (DC) are installed in which looks like an "articulation frame", located in the box between the two triangular sub-doodads (EOT). Converter Assembly (MW) and the Dilithium Crystal Converter Assembly, DCCA, (EOT) are terms mentioned. Is the DC "articulation frame" the DCCA itself, or does it just hold the DC and transports them into and out of the DCCA (which holds up to 4 crystals) thats connected inside the M/AM reaction chamber? I prefer something like the later.
5. Doodad double cylinder shape may suggest:
   1. some sort of safety system node into the reaction chamber to insert and extract the DC articulation frame in and out of the DCCA while in the active M/AM reaction. Purpose: the design suggests either a dual field containment system to breach the active reaction, and/or
   2. they may may be dual energizing coils to on-line re-amplify the DC to replace the off-line dilithium crystal energizer (DCE) seen in TAF https://memory-alpha.fandom.com/wiki/Energizer. Since Mres likes the new term "synchrotron", which sounds cool , it could be the dilithium crystal synchrotron (DCS) or dilithium synchrotron (DS) or just synchrotron for short.
   3. hate to add another option but, the doodad could be the main energizer itself where the super-charged DC are inserted to extract the stored energy and send it into the ship EPS via the pipe cathedral.
   4. Season 3 put an access hatch on the box that can remove the DC from the floor mounted doodad that also removes it from the DCCA which is in the active M/AM reaction chamber. The Star Trek web site (http://www.startrek.com/database_article/dilithium-chamber-hatch) gives: Dilithium Chamber Hatch (DCH), "Exterior door of the matter/antimatter reaction chamber, part of the warp drive of a starship. The hatch gives crewmen access to the dilithium crystal articulation frame when the frame requires service or the crystals need replacing." A good name for the hatch if it was directly attached to the M/AM reaction chamber:
   5. Now, is the floor doodad the actual Matter/Antimatter Reaction Chamber? One cylinder is matter and the other antimatter with the dilithium crystal directly between them. Wow. Probably not; too TNG:
   6. I know we don't like to use TNG terms, but Memory Alpha gives: "The dilithium crystal chamber (or dilithium regulation chamber or matter-antimatter chamber or dilithium chamber) was a component in a starship's warp core that contained the dilithium crystals. No, this sounds like the entire M/AM reaction chamber and "chamber" sounds bigger than that doodad on the floor.
6. How to explain a common doodad if there are multiple engine rooms, especially if one is in the saucer?

My conclusion: It's most likely the dilithium crystal energizer (DCE) (with the access hatch added in Season 3) that energizes the DC when they need re-amplifying, and it conveniently transports the DC in its articulation frame in and out of the DCCA. Systems upgraded are the dilithium energizing and direct access to the dilithium articulation frame on the engineering floor, both systems previously done below decks and now consolidated in main engineering. Any saucer engine room(s) would not have this feature, rather it will look like the Season 1 engine room. Any secondary hull engine room(s) would have this feature. Later in TMP, it was moved into a side room, and even later in TMG, it was not needed anymore since they did it in place. What to call it? I plan to use the term dilithium crystal energizer (DCE) in my posts for now unless TrekBBS come up with better answer...YMMV.

 

[Mytran]

We could have seen two engine rooms, but they could have been so alike that we would have a hard time telling which one we were seeing except for expediency in a given story. This actually fits well with the modular nature of TOS designs. It also means that it would be easy for a ship with no secondary hull to already have a space for its warp engineering area. And an added plus would be that would immediately show how a ship with a secondary hull could be more powerful: twice the engine component space for the same generation.

I could almost believe that, except:

Take a look at "That Which Survives". I think you will be surprised (I was!) that the DTD is no where to be found in that engine room...

I am indeed very surprised!
I can only assume that it was right in the way of where the camera crew needed to be in order to film those particular angles. Compare that to a similar shot in Journey To Babel (bottom right corner) and the absence of the DTD island is made clear:

The absence of the island does raise an interesting question - is this the Engine Room in the secondary hull, the one not seen since Enemy Within? Is the DTD island (which is definitely in an Engine Room accessed by a circular corridor) located in the saucer?

This is why I realized some time ago that I could favor the idea of some kind of power transfer conduit ending in the saucer at the Impulse Syncrotron Unit in Engineering in the Saucer, in addition to an engine room in the Secondary Hull. This is copied and pasted from Miriam Webster:

Definition of synchrotron. 1 : an apparatus for imparting very high speeds to charged particles by means of a combination of a high-frequency electric field and a low-frequency magnetic field. 2 : synchrotron radiation

If this system dealt with boosting Impulse output with warp fields, this description could kind of get close, and at least use an existing name for that structure.

I did wonder about the etymology of that name when you brought it up yesterday. I'm glad it can make some sort of sense!

Though, in some episodes, there is a crystal in in the Impulse Syncrotron Unit, it seems to me that in Secondary Hull Engine Room it is the actual crystal related to warp power, and in the Saucer Engine Room it is serving the purpose of an Impulse Defection Crystal, routing the power to other systems on the ship. As I understand it, the Impulse Deflection Crystal does not just deal with impulse power.

Then in TMP and beyond, the much larger Impulse Deflection Crystals are there as part of getting even more warp power into the saucer for better phasers and defense. Reliant's bigger one could note how it has a lot of firepower for a smaller ship.

If the saucer's crystal is the final one to blow then it could have been used as a yardstick on how the rest of the engineering facilities were faring and ejected for inspection without seriously affecting the rest of the engineering setup (which is what we see in Paradise Syndrome).
It would also serve as the main power converter from the Impulse Engines in case the saucer is separated and on its own.

Any chance its the Dilithium Crystal Converter Assembly (DCCA)? Mentioned twice, Mudd's Women and Elaan of Troyius.

The "Converter Assembly" is first mentioned in Mudd's Women in the context of bypassing the damaged lithium crystal circuits:

SCOTT: One lithium crystal left, and that with a hairline split at the base.
SPOCK: Better rig a by-pass circuit.
SCOTT: Can't. We blew the whole converter assembly.

and then

SPOCK: The entire ship's power is feeding through one lithium crystal.
KIRK: Well, switch to by-pass circuits.
SCOTT: We burned them all out when we super-heated. That jackass Walsh not only wrecked his vessel, but in saving his skin-

The situation in Elaan Of Troyius is more confusing: First the M/AM pods are set to blow, then there's a bomb, then the entire dilithium crystal converter assembly is fused and they can't go to warp. Again, it sees that the crystal circuits are out of commission and so is the usual Plan B (the converter assembly)

In all these cases it seems like the dilithium crystals are transforming the energy produced by the main engines (AKA the nacelles) into some form usable by the rest of the ship, with the bypass assembly being a less efficient alternative for use in emergencies.
@Henoch this would seem to run against the theory proposed in your post which dropped when I was writing this, which imagines a much more TNG setup where the M/AM reaction takes place in the main hull of the ship rather than the nacelles.
I merely offer my thoughts as an alternative


One final tangent:
Since this thread in earlier pages referred to several older threads on the BBS, how about this one?

https://www.trekbbs.com/threads/the-mystery-inside-the-tos-primary-hull-support-pylon.167968/

The OP proposes that the dorsal pylon is not full of windowed lounges (like some deck plans suggest) but mostly support braces and engine conduits, required to connect the primary and secondary hulls together. If this is the case then the dorsal section may not have distinct decks at all, with the count ending at the bottom of the saucer and not restarting until the top in habitable section of the secondary hull.
This will have an impact on where "Deck 12" and "Deck 14" are in relation to everything else (decks referred to in EW/MW and DOTM respectively)

 

[blssdwlf]

I could almost believe that, except:
I am indeed very surprised!
I can only assume that it was right in the way of where the camera crew needed to be in order to film those particular angles. Compare that to a similar shot in Journey To Babel (bottom right corner) and the absence of the DTD island is made clear:

The absence of the island does raise an interesting question - is this the Engine Room in the secondary hull, the one not seen since Enemy Within? Is the DTD island (which is definitely in an Engine Room accessed by a circular corridor) located in the saucer?

Intriguing isn't it? One thing to consider for "The Ultimate Computer" is that all of the S2 engine room DTDs had no dilithium crystal holder. And I haven't had a chance to review S2 scenes but some of the times the DTD might be rotated 180 degrees.

The "That Which Survives" engine room's lack of DTD may or may not put it in the secondary hull since it looks like the DTDs were all changed out for S3 so we could consider all the engine rooms "reset" for determining where they are unless we see an obvious circular corridor outside like in "The Ultimate Computer".

The other thing I guess is whether the DTD is movable or not. In all the S3 episodes that I've reviewed, the DTD location is fairly consistent relative to the ladder on the control wall side but it can move closer or further away from the control wall by at least 1 tubes screen panel width. My Thermian sensibilities want to classify those differences as separate engine rooms

One final tangent:
Since this thread in earlier pages referred to several older threads on the BBS, how about this one?

https://www.trekbbs.com/threads/the-mystery-inside-the-tos-primary-hull-support-pylon.167968/

The OP proposes that the dorsal pylon is not full of windowed lounges (like some deck plans suggest) but mostly support braces and engine conduits, required to connect the primary and secondary hulls together. If this is the case then the dorsal section may not have distinct decks at all, with the count ending at the bottom of the saucer and not restarting until the top in habitable section of the secondary hull.
This will have an impact on where "Deck 12" and "Deck 14" are in relation to everything else (decks referred to in EW/MW and DOTM respectively)

Yeah, I ended up taking a similar approach and didn't have any decks in the neck pylon that added to the deck count. Deck 12 was comfortably in the secondary hull.

 

[Henoch]

Intriguing isn't it? One thing to consider for "The Ultimate Computer" is that all of the S2 engine room DTDs had no dilithium crystal holder. And I haven't had a chance to review S2 scenes but some of the times the DTD might be rotated 180 degrees.

The "That Which Survives" engine room's lack of DTD may or may not put it in the secondary hull since it looks like the DTDs were all changed out for S3 so we could consider all the engine rooms "reset" for determining where they are unless we see an obvious circular corridor outside like in "The Ultimate Computer".

The other thing I guess is whether the DTD is movable or not. In all the S3 episodes that I've reviewed, the DTD location is fairly consistent relative to the ladder on the control wall side but it can move closer or further away from the control wall by at least 1 tubes screen panel width. My Thermian sensibilities want to classify those differences as separate engine rooms

I finished the first round of raw TrekCore HD photo reviews for the engine room spreadsheet, but I'm too busy right now to organize the data and conclusions (I wish I could just attach it as a file). For a quick preview (data is still raw):

• There is at least two engineering control rooms that look like the Season 2 set-up (DTD island with heat exchanger/no crystal tray). It is 100% that the Constellation had two distinct engine rooms (one warp and one impulse based on dialog and photos). Exeter had two, also (not a production mistake). Enterprise, its harder to show, but something's going on.
• Season 1 had two definite cases (TNT, CM) of long curved corridors, one (TUC) for Season 2, but none in Season 3 (island with crystal pop-up top). I'm not counting doors and locations. Only anal Thermians do that. Even a quick cut while walking in a curved corridor (no engine room door in sight) to entering the engine room from the inside shot doesn't rule out non-continuous time and location gaps. It is best if you see them walking in a curved corridor and see them enter the engine room from the outside or at least move toward the door. If you don't count doors, there still could be a curved corridor in the engineering hull. I'll post later.
• All the small changes in Season 1 are chronological so they could just be sequential modifications and not new rooms. Same with Season 3, but there was surprising major changes at the end of the Season; same room with changes. TDOD "3rd or 4th Wall" console shots are most problematic per our previous discussions.
• I think the nub facing on the DTD is a dead end with no rhyme or reason, but I need to look at the data more. In real life, the damn thing is probably on wheels and rolled around to look best on camera or moved out of the way for the camera dolly. I suppose the Season 3 DTD side tray drawer added for Elaan was kind of "shabby" and if they wanted to hide it, then they rotated the island. A rotating island may be my engineered solution for the lack of consistency; wireless controls and power transmission to the big pipe cathedral or a reactor under the floor. Location is not too critical. Trek basis: Remember on power transmission to the ground phaser in the CAGE. Or when M5 started to pull more power directly from the warp engines thru the connector they installed in the wall, zap. Up to that point, M5 was drawing harmless and invisible power levels thru that same connector.
• Odd that the two major engine room first appearances occurred in other ships, namely the DTD island in The Doomsday Machine (modified twice for the two different engine rooms) and the EMM in Mirror, Mirror.
• I'm going to break it into smaller topics, i.e. number of engine rooms by season, nub facing on DTD island, ship tilts, EMM, # Transformers, tool cabinet facing, etc. I have the data by production order, episode number and stardate. Didn't review exact DTD position on floor, in most cases, I was just lucky to see it to get the nub facing.

I'm taking data requests for topics of interest once I start reporting back to you. Live action (I got Netflix) needs to be viewed to clear up some items such as curved corridor outside the entrance is a main item, but that will come last. Transcripts are also used.

Every little change is not a new engine room or there will be 20 of them. Production order is interesting to see little changes come and go based on the episode plot, or stay for a episode or two, then change again. As long as it doesn't affect the chronological order of changes, then it is the same engine room with sequential modifications. Of course, there may be no good reason; its just the way they shot the episode and weren't thinking about continuity (shame on them or is it shame on us for looking too closely).

 

[Henoch]

The absence of the island does raise an interesting question - is this the Engine Room in the secondary hull, the one not seen since Enemy Within? Is the DTD island (which is definitely in an Engine Room accessed by a circular corridor) located in the saucer?

Watched the engineering scenes live action, and yah, it's "missing" or just outside camera frame, but definitely a lot a empty floor space. Scott is looking around the room befuddled that "something is wrong". Maybe it's because the big floor prop is missing? Anyway, the dialog is all about the antimatter bypass valve and other antimatter sabotage stuff, so, I think they are in the secondary hull. Later in Day of the Dove, the big floor prop is back but we get the baffling ladder/wall console shots. Dialog is about cutting off environment control to the saucer decks especially the bridge (not warp control). Is this the same "engineering control room" that Riley took over in the Naked Time? An engine room in the secondary hull or "below" would have cut off by the Pin Wheel, so, the engine room in the saucer is the only available one to fight over? A lot of guessing. Understanding how the Enterprise power system works might help, but that's a bigger mystery than the engine rooms, themselves. Back to my spreadsheet.

 

[johnnybear]

It's one of those I didn't ask you to check the board lad moments I think!
JB

 

[BK613]

As a prop, I suspect that the the Island is actually three parts that can be locked together, the two triangles and the central rectangle. That is the easiest explanation for how the two drums can swap back and forth. Heck, the larger drum may stack on top of the smaller one for more compact storage.

 

[Timo]

...The in-universe apologist in me immediately wants to conclude that the whole setup is akin to those things firemen and city workers use for accessing underground (in this case underfloor) piping. When dilithium needs swapping, Scotty carts in this massive tool of his, with two tanks for purge gases or antimatter-herding cyclotrons or whatnot, and the central bit that actually links to the dilithium dumbwaiter shaftworks and inserts or extracts the dilithium frame.

The tool can be assembled whichever way, and regulations call for disconnecting and stowing it whenever dilithium is behaving, so that there won't be access-related accidents. But in Scotty's line of work, dilithium is acting up more often than not, so regulations be damned...

Timo Saloniemi

 

[blssdwlf]

Later in Day of the Dove, the big floor prop is back but we get the baffling ladder/wall console shots. Dialog is about cutting off environment control to the saucer decks especially the bridge (not warp control).

In "Day of the Dove" the engine room that Kang has control over apparently can do everything we expect an engine room can provided it wasn't being messed with by the pinwheel alien. They technically would have been able to control life support and ship's course. The alien restored life support and blocked ship's flight control.

KANG: I have captured your engineering section. I now control this ship's power and life-support systems.
...
MARA: They appear to be controlled from another location. Also unable to affect ship's course for return to our empire.
KANG: One of Kirk's tricks. Could he bypass this circuit? What power is it that supports our battle yet starves our victory?​

Here's my observations of the S3 engine room so far from watching the episodes (not reviewing via screenshots):

1. The Engine Room set popped up in "Elaan of Troyus", "The Paradise Syndrome", "The Enterprise Incident", "Is There No Truth...", "The Tholian Web", "Day of the Dove", "That Which Survives", "Let That Be Your Last Battlefield", "The Mark of Gideon", "Lights of Zetar" and finally, "The Savage Curtain".

2. When in the main room area, the DTD is present in most appearances except for "That Which Survives".

3. The DTD's "cap" is usually facing the tubes except for in "Is There No Truth...". The crystal holder box is not reversed and is on the control wall side.

4. The DTD shown in "The Mark of Gideon" for the empty replica Engine Room has the DTD "cap" away from the tubes but features the heat sink instead of the crystal holder.

5. The DTD generally was lined up with the control wall stairs but it's distance from the control wall varied if you used the tube screen panels as a reference.

6. "Let That Be Your Last Battlefield" only showed the Engine Room foyer.

 

[Mytran]

Watched the engineering scenes live action, and yah, it's "missing" or just outside camera frame, but definitely a lot a empty floor space. Scott is looking around the room befuddled that "something is wrong". Maybe it's because the big floor prop is missing? Anyway, the dialog is all about the antimatter bypass valve and other antimatter sabotage stuff, so, I think they are in the secondary hull. Later in Day of the Dove, the big floor prop is back but we get the baffling ladder/wall console shots. Dialog is about cutting off environment control to the saucer decks especially the bridge (not warp control). Is this the same "engineering control room" that Riley took over in the Naked Time? An engine room in the secondary hull or "below" would have cut off by the Pin Wheel, so, the engine room in the saucer is the only available one to fight over? A lot of guessing. Understanding how the Enterprise power system works might help, but that's a bigger mystery than the engine rooms, themselves. Back to my spreadsheet.

Kudos to you for for starting the spreadsheet - it's been on my to do list all week without success so far! Of course, people on this board keep on making fascinating new discoveries and I am very easily distracted...

I would be mostly happy to have all but two of the Engine Room appearances (EW and TWS) be in the saucer; circular corridor appearances are matched and if the DTD island prop is used for monitoring a single dilithium paddle as a representative of the whole (as per my earlier post), then that explains its appearances in those episodes. I imagine that the other dilithium circuits are in a larger and more complex piece of machinery deep below the secondary hull Engine Room, working night and day to convert M/AM reaction energy into a form usable by the rest of the ship's systems (or mediate the M/AM reaction if you prefer a TNG setup)

The only problem with that is DOTD, because the pinwheel alien explicitly exits into space through the side of the secondary hull. A slightly deviated route outside is believable - but to travel all the way down the dorsal and then a few more decks first would suggest a more essential purpose - did it leave a portion of itself down there, perhaps perpetually blocking the efforts of the trapped crewmen to escape? Does anything in the episode suggest that the pinwheel alien can divide itself like that, or appear in more than one place at once? Its influence is certainly felt everywhere, but is that enough to support this wild supposition?
It's all a bit unsatisfactory IMO.

As a prop, I suspect that the the Island is actually three parts that can be locked together, the two triangles and the central rectangle. That is the easiest explanation for how the two drums can swap back and forth. Heck, the larger drum may stack on top of the smaller one for more compact storage.

That was my thought as well, since the only consistent feature is the middle section with the off-centre raised block (always on the ladder side of the room). I wouldn't be surprised if the two triangular pieces are just pushed up against the middle bit though - they were probably designed to be as light as possible and just carried into position by the prop guys.

 

[Henoch]

The only problem with that is DOTD, because the pinwheel alien explicitly exits into space through the side of the secondary hull. A slightly deviated route outside is believable - but to travel all the way down the dorsal and then a few more decks first would suggest a more essential purpose - did it leave a portion of itself down there, perhaps perpetually blocking the efforts of the trapped crewmen to escape? Does anything in the episode suggest that the pinwheel alien can divide itself like that, or appear in more than one place at once? Its influence is certainly felt everywhere, but is that enough to support this wild supposition?
It's all a bit unsatisfactory IMO.

The Pin Wheel spends quite a bit time wandering the corridors in the episode. Maybe before it left for good, it quickly roamed the halls looking for some violence to feed off of, but couldn't find any, so it finally left the ship.

 

[Mytran]

Here's my observations of the S3 engine room so far from watching the episodes (not reviewing via screenshots):

1. The Engine Room set popped up in "Elaan of Troyus", "The Paradise Syndrome", "The Enterprise Incident", "Is There No Truth...", "The Tholian Web", "Day of the Dove", "That Which Survives", "Let That Be Your Last Battlefield", "The Mark of Gideon", "Lights of Zetar" and finally, "The Savage Curtain".

2. When in the main room area, the DTD is present in most appearances except for "That Which Survives".

3. The DTD's "cap" is usually facing the tubes except for in "Is There No Truth...". The crystal holder box is not reversed and is on the control wall side.

4. The DTD shown in "The Mark of Gideon" for the empty replica Engine Room has the DTD "cap" away from the tubes but features the heat sink instead of the crystal holder.

5. The DTD generally was lined up with the control wall stairs but it's distance from the control wall varied if you used the tube screen panels as a reference.

6. "Let That Be Your Last Battlefield" only showed the Engine Room foyer.

Our posts crossed earlier and I didn't see this. It's good to know that the DTD island was mostly oriented the same way in S3. Perhaps we were seeing a madness POV shot in Truth/Beauty?
I wouldn't put too much stock in the Gideonite's recreation, their info is only good enough to convince a drugged up Kirk

The Pin Wheel spends quite a bit time wandering the corridors in the episode. Maybe before it left for good, it quickly roamed the halls looking for some violence to feed off of, but couldn't find any, so it finally left the ship.

It rather undermines the drama of the final scene in DOTD, but then again everything else in that episode strongly suggests a saucer based Engine Room (they make specific mention of decks 6 & 7). Perhaps the alien exited the Engine Room and fell down the main turboshaft to the secondary hull? The exit point on the secondary hull is in line with the direction of the aft dorsal, so might that even suggest a diagonal turboshaft?
http://tos.trekcore.com/hd/albums/3x07hd/dayofthedovehd1411.jpg

A final thought on the nature of the Engine Room in the secondary hull being rarely visited - this would gel with Riley's state of misery (and isolation) about being sent down there in COK - and why Kirk felt it would keep him safe (if the actors were being accommodated in the saucer). Unfortunately, Kirk's little trip with Lenore to the observation gallery seemed to have messed up that plan of his, as she was able to slip back later to the same hull and commit attempted murder.

I wonder what staffing levels are like between the various appearances of the Engine Room?

 

[blssdwlf]

Our posts crossed earlier and I didn't see this. It's good to know that the DTD island was mostly oriented the same way in S3. Perhaps we were seeing a madness POV shot in Truth/Beauty?

Well, we do see the DTD in "non-madness POV" shots so unfortunately it is oriented differently than the other times we see the DTD in S3...

I wouldn't put too much stock in the Gideonite's recreation, their info is only good enough to convince a drugged up Kirk

That's possible I figure there could also be 2 other possibilities:
1. The Gideonites scanned and replicated a starship that visited earlier that had S2 engine tech thus the replica engine room looks like it was from S2 or...
2. There's at least one S3 engine room with S2 gear (heat sink) in it...

It rather undermines the drama of the final scene in DOTD, but then again everything else in that episode strongly suggests a saucer based Engine Room (they make specific mention of decks 6 & 7). Perhaps the alien exited the Engine Room and fell down the main turboshaft to the secondary hull? The exit point on the secondary hull is in line with the direction of the aft dorsal, so might that even suggest a diagonal turboshaft?
http://tos.trekcore.com/hd/albums/3x07hd/dayofthedovehd1411.jpg

A final thought on the nature of the Engine Room in the secondary hull being rarely visited - this would gel with Riley's state of misery (and isolation) about being sent down there in COK - and why Kirk felt it would keep him safe (if the actors were being accommodated in the saucer). Unfortunately, Kirk's little trip with Lenore to the observation gallery seemed to have messed up that plan of his, as she was able to slip back later to the same hull and commit attempted murder.

I wonder what staffing levels are like between the various appearances of the Engine Room?

I dunno. The Klingons had control of Deck 6 and part of Deck 7 before they captured one of the engine rooms. I'm thinking that the Engine Room was in the engineering (secondary) hull.

The phrase "below decks" is interesting. Is that below a "main" deck? Would that be Deck 5 or 7? And it would seem that the pinwheel alien made sure 38 out of 430 were untrapped so there had to be some also trapped in their crew quarters or duty stations all across the ship.

 

[Henoch]

Season 1 Engine Room (by production order):

1. 6/29 appearances as the engine room. (TEW, TNT, TCOTK, CM, TIY, SS)
2. 2 rows of bottom pipes seen in pipe cathedral in TEW and TNT, the first 2 appearances of the room. (Pipes moved for conversion into Gym and Phaser Control room.) 3 rows of bottom pipes seen afterward in all engine rooms S1, S2, and S3.
3. 2 occurrences of long curved hall outside the engine room, TNT and CM.
4. Table size control console in the engine room. Seen 5/6 times, 5 times under control wall panel, 1 time moved to middle of room. Not seen only in TEW.
5. 1 incident of extended ship tilt to port on bridge shows port tilt in engine room (TIY). Pipes are astern of the engine room.
6. Could not confirm any cases of number of Transformers changing during the same episode. 4/6 had 2 Transformers, one episode (TIY) the area was not shown, and one (SS) only 1 used in close up back ground behind actor otherwise the area was not shown. Cannot confirm if less than 2 Transformers were in the room.
7. Converted into other sets four times: Gym (CX); Fwd Phaser Control Room (BOT); Gym/Theater (TCOTK); Starbase Computer Center (TM, P1)
8. 1 episode (TNT) showed a wall segment next to the control console. Couldn't confirm wall missing or there in CM (area was in black shadow).
9. "Billy clubs" added to bank of consoles in last episode (SS) to use the S1 engine room.

My Summary: The Engine Room made 6 appearances out of 29 episodes. Long curved corridor to the Engineering Control Room suggested for 2 episodes which puts the room with the wall segment next to the console in the saucer. Pipe cathedral definitely are pointing to the stern of the ship in TIY. Otherwise, the room appeared to be the same one with only 4 small changes: 3 bottom pipes moved up after TNT; movable wireless control console; short wall segment (possible temporary partition) came and went; and billy clubs added. Of course, YMMV.

 

[Henoch]

That's possible I figure there could also be 2 other possibilities:
1. The Gideonites scanned and replicated a starship that visited earlier that had S2 engine tech thus the replica engine room looks like it was from S2 or...
2. There's at least one S3 engine room with S2 gear (heat sink) in it...

I think it was a shrewd clue that something is wrong on this fake Enterprise! Note that Kirk did not physically visit this room, or he may have noticed something is wrong. This has my vote.

Taking the other side's argument, if there is a S2 (heat sink) room, then it might be in the saucer since it does not have the dilithium crystals that is found in the S3 (paddle holder) room.

 

[Mytran]

Well, we do see the DTD in "non-madness POV" shots so unfortunately it is oriented differently than the other times we see the DTD in S3...

That's fine, I don't really like "POV" shot explanations anyway

I dunno. The Klingons had control of Deck 6 and part of Deck 7 before they captured one of the engine rooms. I'm thinking that the Engine Room was in the engineering (secondary) hull.

Spock's exact words are:

The Klingons control deck six and starboard deck seven, while we control all sections above.

If the floor of the saucer engine room is on Deck 7 (just shy of the starboard area) then the upper level is on Deck 6...which is exactly where the Klingon attack comes from.

The phrase "below decks" is interesting. Is that below a "main" deck? Would that be Deck 5 or 7? And it would seem that the pinwheel alien made sure 38 out of 430 were untrapped so there had to be some also trapped in their crew quarters or duty stations all across the ship.

This wording of the script has been the bane of my life for 20 years! There's not enough space in the lower saucer to accommodate 400 crew and barely enough space (or a decent reason) for them to be clustered in the secondary hull! Unless that's actually where most of the recreation facilities are located? It would help to explain all the windows!
I think some manipulation by the Pinwheel alien was definitely involved to herd the rest of the crew to a lockable location. Maybe it triggered a saucer separation and then closed the dorsal door behind them?

Season 1 Engine Room (by production order):

1. 6/29 appearances as the engine room. (TEW, TNT, TCOTK, CM, TIY, SS)
2. 2 rows of bottom pipes seen in pipe cathedral in TEW and TNT, the first 2 appearances of the room. (Pipes moved for conversion into Gym and Phaser Control room.) 3 rows of bottom pipes seen afterward in all engine rooms S1, S2, and S3.
3. 2 occurrences of long curved hall outside the engine room, TNT and CM.
4. Table size control console in the engine room. Seen 5/6 times, 5 times under control wall panel, 1 time moved to middle of room. Not seen only in TEW.
5. 1 incident of extended ship tilt to port on bridge shows port tilt in engine room (TIY). Pipes are astern of the engine room.
6. Could not confirm any cases of number of Transformers changing during the same episode. 4/6 had 2 Transformers, one episode (TIY) the area was not shown, and one (SS) only 1 used in close up back ground behind actor otherwise the area was not shown. Cannot confirm if less than 2 Transformers were in the room.
7. Converted into other sets four times: Gym (CX); Fwd Phaser Control Room (BOT); Gym/Theater (TCOTK); Starbase Computer Center (TM, P1)
8. 1 episode (TNT) showed a wall segment next to the control console. Couldn't confirm wall missing or there in CM (area was in black shadow).
9. "Billy clubs" added to bank of consoles in last episode (SS) to use the S1 engine room.

My Summary: The Engine Room made 6 appearances out of 29 episodes. Long curved corridor to the Engineering Control Room suggested for 2 episodes which puts the room with the wall segment next to the console in the saucer. Pipe cathedral definitely are pointing to the stern of the ship in TIY. Otherwise, the room appeared to be the same one with only 4 small changes: 3 bottom pipes moved up after TNT; movable wireless control console; short wall segment (possible temporary partition) came and went; and billy clubs added. Of course, YMMV.

Outstanding work! How did I not realise that the 3 horizontal pipes made their first appearance in COK and not CM? It certainly supports the idea that Enterprise had a refit after the events of BOT and in real life that changes were made to the set only after it had been disassembled for a while. Maybe a stagehand broke something?

 

[Maurice]

For The Cage, they still used stages 15 and 16 at Desliu-Culver, but the Bridge was by itself on 15, all the other Enterprise sets were on 16. I put this together from a couple screencaps that shows the extent of the Stage 16 sets, except for the Transporter Room to the right, couldn't get a decent shot from that side:

Basically, they had the three sets adjacent to each other, connected by the bit of corridor. The briefing room stayed in the same spot, that second A-frame between Pike and the briefing room was moved elsewhere in the set in WMNHGB. What was the door for Pike's quarters became the turbolift door.

Just curious, what is your source for the bridge being alone on Stage 15?

 

[Henoch]

Outstanding work! How did I not realise that the 3 horizontal pipes made their first appearance in COK and not CM? It certainly supports the idea that Enterprise had a refit after the events of BOT and in real life that changes were made to the set only after it had been disassembled for a while. Maybe a stagehand broke something?

Thank you, working on S2 and S3. It was more likely: "Hey, I spent money on three pipes and I want to see them. Raise them up."

 

[Firebird]

Just curious, what is your source for the bridge being alone on Stage 15?

I believe I pulled that from the shooting schedule.

 

[Maurice]

I believe I pulled that from the shooting schedule.

I thought the planet set was on Stage 16. I know they had three stages for the pilot. Time for me to go back and look at the shooting schedules again.