Why is the lower Saucer deck concave?

[Imaus]

On the TOS-Constitution and the Refit Enterprise, the Saucer's second deck, the lower deck, is concave.

Why is this? It seems to take out a lot of usable space, pushing usable ('usable' being, say, a 3m deck) to the rim.

The DIS-Ent has a solid two decks, but even the refit sort of has a concave...or maybe it's a trick of the eye? It's two full decks with a half-under deck? The lower windows do seem to be a bit higher than the floor of the concave.

 

[BillJ]

Because Matt Jefferies was a design genius. It gave the ship a look of being complex.

 

[ZapBrannigan]

Because Matt Jefferies was a design genius. It gave the ship a look of being complex.

Yes, I'd say it was pure aesthetics. And at the design stage, Jefferies and Roddenberry really weren't thinking about fitting realistic decks into the ship, thought out with the ceiling heights allowed for.

The Franz Joseph Blueprints package has outer-ring crew quarters on Deck 7 with a bare two-meter deck height (inboard profile), and most of the undercut accounted for with storage rooms (Deck 7 plan view). He makes it work.

 

[CorporalCaptain]

The likely reason was that it looks cool.

 

[mike hill]

RL (as has already been mentioned) - so it looks cool.

My in-universe reasons :-
1) To provide lift in case of emergency saucer atmospheric landing.
2) To conform with the warp field.

 

[Timo]

3) They built a thin, sleek saucer, but the rat race called for more lateral sensors, so they ultimately installed a taller rim.

Timo Saloniemi

 

[Mytran]

Real world reason; I suspect it was to add more curves to the underside of the ship and help define its shape, something that was extra important on the low-res TVs of the time.

3) They built a thin, sleek saucer, but the rat race called for more lateral sensors, so they ultimately installed a taller rim.

Timo Saloniemi

That's long been my preferred interpretation as well, or at least a close variant. There's absolutely no justifiable reason to hamper access to the outer part of the ship by design.

In my mind the outer saucer was originally just one deck thick (we see in TOS that the corridors and rooms are very tall). However, at higher warp speeds the structural integrity around the saucer started to have problems, so additional SIF relay modules were installed on the underside of the rim to compensate for this. Once this was found to be successful the hull was contoured to fit and the perceived undercut was born.

As to why an additional full deck wasn't added as well (or later in the refit) I assume it was down to how the saucer was originally constructed and that it wouldn't have handled the extra tons of tritanium beams etc in order to make a habitable space. Plus, the crewmen don't mind sharing quarters, right?

 

[Forbin]

The saucer is designed to separate in case of emergency, and land on a planet as a last resort. The concavity is aerodynamic camber to help provide aerodynamic lift as the saucer glides to a hopefully-controlled emergency landing. Jefferies was a smart dude.

 

[Timo]

That's long been my preferred interpretation as well, or at least a close variant. There's absolutely no justifiable reason to hamper access to the outer part of the ship by design.

Yet conversely, Starfleet seems to think the outer parts can remain inaccessible just fine: ring-type primary hulls now proliferate, and never mind free-floating nacelles and hull segments.

Might be it's more important to have stuff out there, at a certain distance from other stuff, than to provide access to that stuff. Sensors today tend to dangle at the ends of accessibility-limiting masts and poles, too.

But seeing the extended rim as analogous to those bulges navies add to ship hulls after discovering stability problems is cool, too. Doesn't necessarily mean the ship was originally designed wrong. Perhaps improved propulsion indeed called for improved SIFs. Or perhaps that's where new shield generators go when Klingons introduce improved disruptors?

Timo Saloniemi

 

[Mytran]

The saucer is designed to separate in case of emergency, and land on a planet as a last resort. The concavity is aerodynamic camber to help provide aerodynamic lift as the saucer glides to a hopefully-controlled emergency landing. Jefferies was a smart dude.

I'd be interested to know just how aerodynamic the saucer actually is and how much difference that concavity would make.
Do I vaguely recall seeing experiments somewhere done on the shape or did I imagine that?

 

[Imaus]

All good points. It does add some depth-of-field? to the lower saucer, it could be aerodynamic, and...honestly the more I look at it, it looks like you COULD fit two decks in there, and there's a bit of a overhang, though the zenith? really cuts in deep.

 

[Mytran]

All good points. It does add some depth-of-field? to the lower saucer, it could be aerodynamic, and...honestly the more I look at it, it looks like you COULD fit two decks in there, and there's a bit of a overhang, though the zenith? really cuts in deep.

Yeah, it cuts in really deep
Not much headroom there

(Full credit to Shaw)

 

[TIN_MAN]

What about the bevel that we see on the lower outer edge of the saucer rim in some of Jefferies early drawings?
might his suggest that he intended it to indicate (in universe) some sort of modification to an earlier one level rim, thus creating the "overhang" at the edge, and the "undercut" on the bottom? Both his early drawings and the 33 inch miniature seem to indicate a thinner saucer edge than we see in later versions.

 

[XCV330]

it gives it the look of a ship's bow in certain camera angles

 

[valkyrie013]

What Concave saucer bottom?.. the Enterprise doesn't have one.. ....

Always liked the concave saucer, makes it look nicer and faster.. don't like how JJ and Disco got rid of it..

 

[Maurice]

All good points. It does add some depth-of-field? [...]

No. It affects DOF not at all.

 

[NCC-73515]

The saucer is designed to separate in case of emergency, and land on a planet as a last resort. The concavity is aerodynamic camber to help provide aerodynamic lift as the saucer glides to a hopefully-controlled emergency landing. Jefferies was a smart dude.

I'd be interested to know just how aerodynamic the saucer actually is and how much difference that concavity would make.
Do I vaguely recall seeing experiments somewhere done on the shape or did I imagine that?

It's basically a parachute

 

[BK613]

I'd be interested to know just how aerodynamic the saucer actually is and how much difference that concavity would make.
Do I vaguely recall seeing experiments somewhere done on the shape or did I imagine that?

From the Before Time:
http://www.physics.uq.edu.au/lp/lasdiag/enterp.php

 

[BK613]

It's basically a parachute

Frisbee

 

[Mytran]

From the Before Time:
http://www.physics.uq.edu.au/lp/lasdiag/enterp.php

Thanks, that may be what was lurking at the back of my mind!