Some Old Ship Design Ideas

I’m afraid the designs are too simplistic for me to give effective commentary, but at a glance I commend you for making these radially symmetric; it gives them a more technical, realistic hard science fiction feel than most designs, and you have the two benefits that you don’t need all that much debris/radiation shielding at the front or reactor shielding (if your engines are nuclear) at the back, and you have a relatively large surface area to volume ratio for passive heat disposal. I’m guessing that the engines are in the back for all of these, so you’re going to need thrust vectoring nozzles or heavy gyroscopes to steer, and I doubt any of these will be all that maneuverable; that being said, with the huge distances and velocities involved in spaceflight, being able to spin on a dime isn’t much of a priority, especially if your guns can do it for you (it’s definitely a lot easier to make them do it).  

Given the length of these ships, I think they could make good use of spinal weapons. I personally think little of them for general ship-to-ship combat because about the only way to aim them is to steer the whole ship around, but this isn’t a problem when facing slow or barely moving targets, such as planets, asteroid or space stations, and they are capable of truly massive firepower. Moreover, in the case of mass drivers, they can be used not just as weapons but to boost other vessels, such as probes and fighter craft.

The Tonga II’s design seems a little problematic; if the weapons platforms are on the cylindrical subsections, the spherical FTL drive creates a huge blindspot for both sides, and the rearward nozzle creates a blindspot for rear weapons (unless you’ve put the weapons on the edge of the nozzle itself, but the first point still stands). This isn’t a major problem if you have enough weapons, but I think it would pay to place them on a disc protruding beyond the edge of the sphere, allowing you to redirect all of your firepower in a single direction if necessary; moreover, depending on what the disc is made of, you could use it to shield the potentially delicate FTL drive (especially if paired with another disc), and if it’s truly large, you could host a rotating centrifugal habitat within.

For some reason I like the idea of the Harabi missile platform having large maneuvering jets, being able to speed into position and swivel to face its target before firing, even though I know that would defeat the point of using missiles. More practically, I think such platforms would probably use feeble thrusters to slowly move into position and let their missiles cross the final kilometers at greater speed (likely with far more inefficient drives), minimizing engine size and maximizing payload. This strategy would probably be even more effective if the Harabi is meant to be an orbital platform, in which case there isn’t much distance it has to cross.