"Clamshell" Shuttlebay Hatches

[FalTorPan]

I've never understood how the "clamshell" hatches of shuttlebays on various Feddy ships (Constitution, Constitution refit / Enterprise, Excelsior, Ambassador, et. al.) would really operate.

As fans have built 3D models of Trek ships -- especially the TOS Constitution -- many redesign the shuttlebay hatches to be nested, near-spherical segments which overlap one another when both open and closed. Even ignoring that this represents a change in design from the doors as seen on the exterior filming miniature -- which resemble "flush" segments -- the design still doesn't address certain questions...

What "glues" the segments together when closed in order to seal the compartment? Force fields? Ultra-advanced, flexible materials?

What keeps the various segments aligned at the top, where each segment tapers to a point?

Then consider the Excelsior. How in the world would its hangar bay doors work? Each segment has a shape which differs radically from the shapes of its neighbors -- so much so that I can't imagine them sliding over one another to open and close. Might the Excelsior's door segments be flexible structures rather than rigid structures? If so, then might the Constitution's door segments also be flexible structures?

Maybe the door segments are made from an increasingly less-exotic-sounding material that's rigid under certain conditions, and flexible under other conditions.

Thoughts? And has anyone attempted to create a 3D model of the Excelsior's hangar bay section with animated doors?

 

[Cary L. Brown]

You're asking two very different questions.

1) In the case of a ship like Excelsior, the doors simply cannot function in any mechanical fashion. Same with many of the supposed "cargo hatch" doors on the 1701-D. That's what you get when you let graphic artists do the job of engineers!

However, in the case of the Connie variants, and as far as I can tell, the Ambassador, the mechanism is perfectly rational.

To see an example of how this works, you need only go to what Jeffries was referencing when he came up with it... a huge hangar found in the South Bay area (I think it's in San Jose, but in any case it's in the general San Francisco region). The doors on that hangar are almost exactly like what you see in TMP, actually. That's because Probert knew of this hangar and used it as a design reference when he was doing his stuff on this model.

The idea of swinging clamshell-type doors like that is not only not a new concept, it's one that's been used in real life, in other words.

Of course, that hangar is not air-tight. But as an engineer, it's not hard for me to see solutions for ways to make that sort of thing sealable. We seal much more complicated mechanisms quite regularly, again, in real life. All you really need are inflatable seals between adjacent segments... blow them up and they expand to fill the gaps... deflate them and they retract.

It's true that the models were made with the segments evidently along the same surface. Yet that's not necessarily what was REALLY going on. If someone really built the 1701, in full-scale, or built a large-scale model of that region, you'd probably see a slight offset between segments.

On the other hand, you could also have a more complicated mechanism for each "pedal" of the door structure... so that they would "fall into place" side by side when closed but would offset themselves when opening. Again, that's easily accomplished and has been done many times in real life.

SO... as long as the door section is of a uniform cross-section throughout the rotational path (or very nearly so), you can easily make the doors work.

Here's an example of a fully-articulated door system I've built into my "Vega" class design.





Note that there IS an offset... but in this case, the door segments are NESTING... meaning that most central elements actually slide inside the next adjacent door segments. This allowed me to seal on both the inside and outside "lip" of the door segments. There would be an expanding seal at the top and bottom edges, as well... those would retract prior to door operation.

You might notice, if you've ever looked at the Vega class, that there are elements that resemble the Excelsior. I needed certain functionality, and I had thought about the very issue you brought up here many times. So my "what I'd have done to make these things make SENSE" solution for Excelsior's secondary hull topside is something you'll see implemented on Vega.

EDIT: Sorry 'bout the full-sized images. I work on a system with a HUGE hi-res monitor, where those only take up 2/3 of the width of the thing... so I didn't think about the issues it'd cause. My bad...

 

[Trekker4747]

Dude, great as those pics are they're stretching the hell out of the page, mind fixing that?

 

[uss_griffin]

^ That's very common here on trekbbs. I use the zoom-images-out bookmarklet to fix the pages.
You can get it here.

 

[Trekker4747]

Huh. That's pretty cool.

Thanks!

 

[Trekker4747]

"Possible" or not (I suspect that in a universe with transporters and FTL drives "crazy flexibile metal" exsists too. ) I prefer the look of "clamshell" doors. Looks better than the Overhead Door Co. style the Ent-D and especialy the Voyager had. Voyager's was the worst. It looked EXACTLY like a garage door. It even had a regular people-door right next to it like garages do.

 

[Sec31Mike]

The regular door next to Voyager's main shuttle door was probably used for EVA entrance and exit to assist in shuttle operations and external ship repair.

 

[Forbin]

Trekker4747 said:
"Possible" or not (I suspect that in a universe with transporters and FTL drives "crazy flexibile metal" exsists too. ) I prefer the look of "clamshell" doors. Looks better than the Overhead Door Co. style the Ent-D and especialy the Voyager had. Voyager's was the worst. It looked EXACTLY like a garage door. It even had a regular people-door right next to it like garages do.

And just like real naval vessels do:
http://www.navy.mil/view_single.asp?id=40117

Note the personnel door inset into the helicopter hangar door on the USS Anzio. I'm fairly sure that's what Mr Sternbach was thinking of when he designed Voyager's hangar.

 

[Sec31Mike]

AAAhhhh. Remembering my Navy days spent in an aircraft hangar.

 

[Colonel Midnight]

Forbin said:

Trekker4747 said:
"Possible" or not (I suspect that in a universe with transporters and FTL drives "crazy flexibile metal" exsists too. ) I prefer the look of "clamshell" doors. Looks better than the Overhead Door Co. style the Ent-D and especialy the Voyager had. Voyager's was the worst. It looked EXACTLY like a garage door. It even had a regular people-door right next to it like garages do.

And just like real naval vessels do:
http://www.navy.mil/view_single.asp?id=40117

Note the personnel door inset into the helicopter hangar door on the USS Anzio. I'm fairly sure that's what Mr Sternbach was thinking of when he designed Voyager's hangar.

On our new class of cutter being built - the "people-sized door" was actually a requirement (in addition to the "garage-style door"), mainly for safety reasons.

(Basically as a secondary means of escape, in case the hangar door jams which, unfortunately, tends to happen fairly regularly.)

Plus, it also helps with maintaining HVAC (and CPS) boundaries.

Cheers,
-CM-