...those same features on the Miranda appear on the Constitution too, but not as deflectors.
We don't really know that, though. Quite possibly the grey half-domes or quarter-spheres are the main deflector system of the
Constitution, and the blue disk in the middle is "just" a sensor.
If we really want objective support for the idea that the disk is the deflector and the grey domes are something else, we'll have to move over to the
Excelsior class. That one features the blue disk, virtually identical to the
Constitution one, but doesn't feature the grey domes - and dialogue establishes that the deflector is doing stuff when the blue disk of the
Enterprise-B shoots out a beam in ST:GEN.
As for the Oberth... I am not entirely convinced that the "secondary hull" is a hull
TNG "Hero Worship" is unambiguous on this. LaForge shows and tells us that the
Vico of
Oberth class has primary and secondary hulls, and the secondary hull (the ventral pod) is shown having multiple habitable decks, and in addition containing a "core" which appears to be the warp core of the vessel.
Of course we may argue that a 2360s
Oberth is internally different from a 2280s one. And it certainly isn't implausible that a ship that began as a primary hull plus a virtually empty ventral pod would "grow" so that inhabitable spaces would expand into the pod. It is even possible that an original warp powerplant in the primary hull was later replaced by a larger and more powerful one that had to be installed "outboard", in the pod. Similar major repositionings of power systems have happened in naval history, especially when ships were converted from coal to oil firing.
Since apparently this is not a new sentiment, I'll again agree that "deflectors" make more sense if they're integrated into the warp nacelles, where a huge quantity of ship's power is being channeled (or produced) anyway.
Agreed. However, terminologically we cannot abandon the "main deflector dish" in front of the secondary hull of many starships, because its role, designation and function is multiply confirmed by dialogue and visuals. The Bussard domes may well feature in the deflector system, but they have never earned the designation or status of a central element in that system.
Timo Saloniemi