The warp nacelles are modular fer shure: in "Skin of Evil", we see the original Type 9 with the Galaxy style nacelles, the TM shows 9a with the modern angular style, and Janeway and Chakotay of course get the 9b with Intrepid nacelles in "Resolutions"... Timo Saloniemi
It has been my understanding that the broken, half buried Shuttlecraft 13 from “Skin of Evil” is depicting a version of the Type 7.
...Which is basically what the TNG TM Type 9a is, only with different nacelles. That is, the cockpit in "Skin of Evil" is of course common with Type 7 - but the exterior of Type 9 would nicely cater for that, since the exact window shape never is seen much from the inside in any use of that set/prop (least of all in "Skin of Evil"), and common cockpits across a whole fleet of designs would make sense. In turn, the "Skin of Evil" stern jutting out of the rock doesn't bear the slightest resemblance to the stern of Type 7, but it doesn't take all that much squinting to see said butt contours in the ambiguous art for the TM craft. It's a chore to load cargo onto a Type 7, which has no "real" doors on the prop but ostensibly has a narrow ramp in the middle of the bow (too narrow for cargo), then two gullwingish side doors, at least in most models (too high-mounted for cargo), and potentially a stern door with the impulse engine mounted in the middle of it (probably not the best way to bring in bulky items even if the door is wider than the bow ramp). A "companion" cargo design as depicted in the TM sure makes sense, then. Although whether the fancy ovoidish depression at the stern of the "Skin of Evil" craft is a practical cargo door is again debatable... It might work better as a big rear window, Danube class style. (Perhaps there are optional stern modules, some with big rear ramps, others with this nice window? ) Timo Saloniemi
I think you could make the point that the Skin of Evil shuttle was a different design. I’d like to see it fleshed out. In truth, it was just a general approximation of Probert’s designs
...There then being a story behind why it was such a miserable failure. I mean, the stern doesn't look at all like Type 7, not even in terms of the paint job. Yet it isn't a trivial piece of blocky plastic, either - it has contours, only they are completely wrong. Why? Did somebody go to the trouble of creating a deliberately incorrect, that is, deliberately different design (in which case the non-matching Okudagram with the regular Type 7 art tells us people didn't share ideas in time - which of course is par for the course)? Or did there exist a piece of plastic with those complex contours, and it was utilized here to save time and money? Funnily enough, "Skin of Evil" is one of the very few cases in TNG where an entire interstellar trip in a warp-capable shuttle is the unavoidable inference. We never actually see shuttles go to warp in TNG, or hear the associated dialog, and we can usually make the alternate inference that the shuttle was dropped off within impulse distance of its target. Perhaps a shuttle from this era needs to be bigger than Type 7 in order to really go solo on interstellar A-to-B? Perhaps Shuttle 13 here was more like the runabout of the era? Timo Saloniemi
It might be an armored shuttle...it would have to be to survive that damage Double strength inertial dampeners
Well, an intact body and optionally broken-off nacelles is how every shuttle crash turns out. If anything, this would have been a chance to do more damage, since the wreck wasn't a prop but a model. Slamming through bedrock works pretty well for Trek spacecraft in general, including ones with explicit problems with main and auxiliary power. IDFs and SIFs appear to be reliable and capable tech! Timo Saloniemi