So this topic has been bugging me for some time now, and I have a bit of free time to post, so there's no time like the present So the universally accepted design of the TOS D7 has the nacelles as the long thin appendages under the ship at the ends of the wings, analogous to the Enterprise's nacelles. However, in one of Matt Jefferies' original design sketches he has the nacelles on top of the ship (he calls them "power units"): https://vignette.wikia.nocookie.net...ision/latest?cb=20120728010831&path-prefix=en And every time we saw the D7 in TOS firing weapons, the beams always came from what we assumed to be the nacelles: http://tos.trekcore.com/gallery/albums/3x13/Elaan_of_Troyius_338.JPG It's almost as if those appendages were actually meant to be guns/cannons, not nacelles. But if that's the case, then where exactly would the actual nacelles be? There's a structure on top of the secondary hull (which fandom seems to have decided to be the D7's shuttlebay even though there's no evidence that's the case) which has two rectangular structures on either side, which correspond to Jefferies' original intention for the nacelle placement: http://www.ex-astris-scientia.org/schematics/d7-groth-screen.jpg In TMP, the housing between them glows red (see next paragraph): http://www.ditl.org/Images/K/KtiGenral4.jpg Now, let's compare this with the Klingon Bird-of-Prey. Its guns are located at the end of the wings, and the ship's actual nacelle placement is a matter of debate. But in this photo of the ship's underside, what look to be similar structures to the structures on the D7/K't'Inga can be seen, at the base of the wings and between the red glowing centerline of the ship: https://gndn.files.wordpress.com/2011/02/k1.jpg For lack of any other evidence, they seem to be the Bird-of-Prey's nacelles. Now also compare this to the early Bird-of-Prey from ENT: http://www.ex-astris-scientia.org/schematics/early-klingon-bop.jpg It clearly has nacelles on top of the ship between that red glowing structure and are also clearly based on the structures on the underside of the original BoP, which reinforces the idea that the D7's nacelles are actually the smaller structures on top of the ship rather than the larger structures on the wing tips, which could now conceivably be guns/cannons instead to match the design of the BoP. Thoughts?