Enterprise D hull question

[graffy]

Ok, so I'm poking through the TNG Starfleet Tech Guide and I was curious as to how thick the Enterprise D hull is uspposed to be.

Based on what I read about the support structure and the layers of the hull, I figure it must be about 4 feet thick, give or take (depending on what you assume for beam dimensions of the space frame).

Seems a little too thick to me. Any thoughts?

 

[SicOne]

I think it broke down at just shy of 3 feet. Probably a little thicker around the pylon support area of the secondary hull, or at least it just looks that way. I wouldn't necessarily count the beam dimensions of the spaceframe because the beams aren't everywhere.

 

[blssdwlf]

You could look at the windows from any of the interior shots. They seem a lot thinner than 3 feet.

 

[Albertese]

From the TNG Tech Manual, pages 22 and 23, I'm pulling these relevant numbers (I'm not going to reproduce the whole section of text, as most of it is nonsense... (though, I admit, triumphantly clever and well thought out nonsense--thank you Rick Sternbach and Mike Okuda!) but there's only so much phase-transition-bonding I can type through in one sitting...

Going from inside the hull to outside the hull, the numbers I see are...

4.7 cm exterior shell substrate
1.2 cm (x3) biaxially stressed tritanium fabric (for additional torsion strength... duh)
2.3 cm (x4) Substrate fabric layers (only around major structural elements)
3.76 cm (x2) thermal insulation and SIF conductivity layers
8.7 cm tritanium truss framework
4.2 cm radiation attenuation layering and more SIF waveguides.
1.6 cm ablative ceramic fabric fused to a
0.15 cm tritanium foil substrate.

Add them up...

=39.67 cm
or 15.6 inches around major structural elements

--or--

30.47 cm
or 11.99 inches at most of the hull.

Since the edge of the windows on the sets seems to my eye to be about a foot or so thick, I think 11.99 inches is reasonable. It's safe to say that an 11 or 12 inch thick hull at the set's windows would be quite allowable using this data. I have no idea how you guys got to 3 or 4 feet.

--Alex

 

[graffy]

The hull thickness is a given at 1 foot.

However, the hull inside (substrate) is attached to a secondary frame, which is then attached to the primary frame via 2" flexible rods. Then, the outer hull layers are attached to the primary frame.

That means, you have the hull thickness, the thickness of the secondary frame (undefined), the length of the connecting rods, and at least *some* of the depth of the primary frame in the total thickness. You might be able to nest the secondary frame entirely within the major members of the primary frame, but doing some rough guesstimates on member thickness, I can't see how you'd get away with less than 4 feet, though maybe there's a way to get it to 3...

Point being,the cross-section areas spec'd for the primary frame's members are huge. On the order of parking deck reinforced concrete beams. Your looking at beams 3-5 feet deep to accommodate those areas, IMO.(see pages 18 & 19 of the manual for space frame specs).

Anyway, I'm not just randomly nitpicking stuff, here. I was playing around with Blender, and took on Enterprise D as a fun little architectural project... Thought maybe I could build it with the bones...

 

[SicOne]

Ahhhh, 39 centimeters. For some reason I was remembering something like 39 inches or so, rather than centimeters.

And I wouldn't necessarily count the secondary or primary frame in the hull thickness because that frame isn't everywhere. Primary frame is probably something like a big honking beam every 50 meters or so, while the secondary frame is probably every 10-20 meters or so...for example, a secondary frame is probably part of the living quarters wall or partition between compartments, hiding the secondary from the occupants of the ship, as opposed to a big beam that you might find running down the centerline of your living room or unfinished basement. I guess I'd have to take a closer look at the TNGTM to see if they have a view of how the framework ties together or how much space is between the frame members, but going off the top of my head without any caffeine this AM, this is how I picture it.

No worries on nitpicking, Graffy. That's why we're all here, and it's fun.

 

[Albertese]

The hull thickness is a given at 1 foot.

However, the hull inside (substrate) is attached to a secondary frame, which is then attached to the primary frame via 2" flexible rods. Then, the outer hull layers are attached to the primary frame.

That means, you have the hull thickness, the thickness of the secondary frame (undefined), the length of the connecting rods, and at least *some* of the depth of the primary frame in the total thickness. You might be able to nest the secondary frame entirely within the major members of the primary frame, but doing some rough guesstimates on member thickness, I can't see how you'd get away with less than 4 feet, though maybe there's a way to get it to 3...

Point being,the cross-section areas spec'd for the primary frame's members are huge. On the order of parking deck reinforced concrete beams. Your looking at beams 3-5 feet deep to accommodate those areas, IMO.(see pages 18 & 19 of the manual for space frame specs).

The Primary Truss Frames are an average of 1.27 m^2 in cross section. If they were a square, this would mean that each side was a little over a meter, let's say around 3 1/2 feet. They could be rectangles, either narrower and deeper or wider and shallower. These are spaced an average of every 25 m across the hull. The exterior hull would be affixed to these, like how the plywood sheeting is nailed to the 2x4 studs of a stick framed house. The difference is that on the house, the studs are internal to the wall and a layer of drywall covers them on the interior for a smooth finished wall, but on the starship, the inside of the exterior hull is the interior wall and the frame members (the studs) simply protrude into the interior volume. As much of the interior volume of the ship is discreet sections designed to be swapped out, I posit that these sections are designed in such a way as to fit between the primary members or incorporate them into the interior design in a way that makes them inconspicuous.

Anyway, I'm not just randomly nitpicking stuff, here. I was playing around with Blender, and took on Enterprise D as a fun little architectural project... Thought maybe I could build it with the bones...

Good luck with your Blender project! that's quite the undertaking, I hope you post your progress, as I'd love to see it!

--Alex

 

[graffy]

Alex, I suspect your suggestion is what I had in mind when I mentioned "nesting" the secondary and primary frames... It's the only way I can see reducing the overall thickness of the hull while accommodating the frame members.

SicOne, as for excluding the hull frame from the thickness, I don't think you can rightly do that, but I'm not sure. That is, at least the thickness of the secondary frame needs to be considered, as I suspect it's members would be generally less than 5m o.c.

Where the primary frame's major members are at 25 m intervals (82 feet), I would certainly exclude them (nesting allows for that), but I still have the primary frame's minor members at 5 m intervals (16.4 feet).

So, at a minimum, I'd argue you'd have the thickness of the minor members from the primary frame, the major member thickness in the secondary frame, the connecting rods between them, and the 12" of hull.

So far as beam dimensions go, I see a variety of approaches. I assumed the beams were twice as high as they were wide (1:1.5 or so might be more the ratio artist's sketch suggests in the manual). Of course, I could adjust the beam depth or possibly try turning the beams on their sides. However, when I do that (and thereby increase the beam width) then there's the difficulty of the major members blocking the hull apertures (windows, shuttle bays, lifeboat hatches, etc).

I might dig up my old steels or reinforced concrete textbooks from college to see if I can come up with a somewhat sensible interpretation of the frame. The performance specs in the tech manual (the gravitational accelerations) could come in handy to figure that out...

Of course, I can also just forget it, invent something that looks right and say the beams are just amazingly strong - you know - like transparent aluminum or something.

 

[Albertese]

I'd love to see some drawings of this; we may be making the same argument but in different ways and we're just confusing each other.

...

I might dig up my old steels or reinforced concrete textbooks from college to see if I can come up with a somewhat sensible interpretation of the frame. The performance specs in the tech manual (the gravitational accelerations) could come in handy to figure that out...

...

Well, these are made of Duranium and Tritanium... which are fun fiction... not concrete and steel. But, if you have the math mojo to reverse engineer from the performance specs in the tech manual, that could be fun to read.

--Alex

 

[graffy]

I'd love to see some drawings of this; we may be making the same argument but in different ways and we're just confusing each other.

...

I might dig up my old steels or reinforced concrete textbooks from college to see if I can come up with a somewhat sensible interpretation of the frame. The performance specs in the tech manual (the gravitational accelerations) could come in handy to figure that out...

...

Well, these are made of Duranium and Tritanium... which are fun fiction... not concrete and steel. But, if you have the math mojo to reverse engineer from the performance specs in the tech manual, that could be fun to read.

--Alex

Nahhh... Not really that interested. But the idea is that the structural mechanics are the same, it's just the material properties that have changed. All you're doing is applying a force to a series of interconnected beams - that's sophomore structural analysis for most Civil Engineering majors (not that I could have solved a frame like this my sophomore year)

 

[diankra]

Does the hull plating thickness actually matter much?
IIRC the tech manual right, the Galaxy class is designed with empty space for later expansion, so the important point is the framework and the integrity of the structural units attached to that. The actual hull plates, except when carrying emitters, etc (and I'd gues they're attached to the main framework whenever possible), is just cosmetic.

 

[graffy]

Does the hull plating thickness actually matter much?
IIRC the tech manual right, the Galaxy class is designed with empty space for later expansion, so the important point is the framework and the integrity of the structural units attached to that. The actual hull plates, except when carrying emitters, etc (and I'd gues they're attached to the main framework whenever possible), is just cosmetic.

In the grand scheme of things, it's not important. I care just because I had half an idea to model the frame as well as the hull and decks. In that case, it does matter. If Rick S. drew the decks 1' or 2' narrower than the hull (and the hull is really three or four feet thick), then the decks are too large and I have to cut out interior space. I haven't tried to determine the hull thickness by comparing how the decks fit on the Sternbach blueprints, though.

Of course, I'll resize the frame members before I cut down the decks, but if I'm going to model the hull and the frame, then I figured it was worth trying to understand the construction as accurately as possible. Thus far, I'm still holding to a thickness of +/-4 feet since I can't reconcile the tech manual descriptions against the more common assumptions of 2' or 3'.

It's nitpicking. But yeah, it's kinda fun.

 

[blssdwlf]

I'm surprised you are not trying to reconcile the thickness of the hull as shown by the windows in the interior scenes. You can just peruse through Trekcore.com for screenshots. But if you're fixed on reconciling only on stuff that didn't appear on screen then more power to you to just use your imagination.

 

[graffy]

I'm surprised you are not trying to reconcile the thickness of the hull as shown by the windows in the interior scenes. You can just peruse through Trekcore.com for screenshots. But if you're fixed on reconciling only on stuff that didn't appear on screen then more power to you to just use your imagination.

Actually, I have thought of using video footage of the sets, but there's a reason I'm more concerned with the technical references. Basically, the blueprints presume to give a generally complete picture of the essential ship... Really, it's a flawed approach because much of the technical details are inherently influenced by the visual details of the models and sets from the show. But I figured it was worth a try. I can deal with +/- 2' hull thickness if I must...

Actually, that reminds me... Maybe I should start another thread to get some feedback on my solution for the varying deck heights in the Sternbach plans.

 

[blssdwlf]

Just an FYI, in the Fan Art section there is a thread that Rick Sternbach is responding to regarding his blueprints.

 

[graffy]

Thanks for that. I was the OP on that thread. Figured it was a dead question. Ignore it for a week or so and look what happens.

As an interesting FYI, I did rescale the Sternbach Deck 10 layout and it appears Rick drew the hull seven feet thick at the points where I measured it.

Seven feet???

Of course, I'm including the thickness of the inked lines in that, so seven feet is certainly too much.

As a sort of cross-check, the corridor clear width on deck 10 comes out to around 6.5 feet. Given that we design sidewalks at five feet to allow two people to comfortably pass, 6.5 feet seems reasonable, though maybe a bit narrow. That said, the blueprints appear to give me all the room I need for whatever I want to do (and I still have no idea what I'm going to do )

 

[blssdwlf]

I figured you had not looked in your thread in a while and thought I'd give you a nudge

The "excerpt" blueprint cross section suggests a much thinner hull thickness though. Out of curiosity, where are you measuring it?

 

[graffy]

I figured you had not looked in your thread in a while and thought I'd give you a nudge

The "excerpt" blueprint cross section suggests a much thinner hull thickness though. Out of curiosity, where are you measuring it?

Deck 10 on the port side. I picked a representative segment to measure. It's not uniform, though. If you look at the aft section, the hull gets noticeably thicker than that...

I'm assuming the empty gap surrounding the rim of the saucer (and the lines on either side) represent the hull itself. In terms of the blueprints, that gives me plenty of room to play...

Actually, now that I think of it, 5 meters of spacing is more than an entire deck height, so it is feasible to exclude the entire thickness of the primary frame from the hull thickness... But I think you'd still have to include the secondary frame, so I don't see that you could make the hull only one foot thick at it's thinnest. Two feet seems feasible, though.

Ok. So maybe I'm agreeing in the end on a thinner hull. I just took the long way to get there.

 

[xvicente]

Despite everything that was said, it should be 47cm.