I haven't figured how to do closer pictures yet.
The CR-1010 Horizon class being upgraded and converted to Constitution class is mentioned in the Book "Ships of the Star Fleet" volume 1.
In SFB and SFC all of the Horizon class ships are listed as Constitution class heavy cruisers and in the game the F-CA names and registery numbers either shop converts from this class or the subsequent Archon CA-1370 class.
I've always pictured the Horizon class, in my mind's eye, as looking like a cross between a Constitution and a Declaration, resembling both in key features and design.
I've had this project in mind for over a year but was more occupied making Klingon models, a few Kzinti ships and other stuff.
After seeing the postings for the pre-TOS Confederation class heavy cruiser, I figured that there would have to be a small stepping stone in design in order to show a transition stage between the Confederation and the Horizon class, which is why I also created the Equinox. This gives a smooth design evolution back to the Baton Rouge class and fowards through the Horizon towards the Archon, Constitution, Endeavor, Achenar and Tikopai class heavy cruiser that followed on.
The saucer isn't mine. It came from Anduril's Archon class USS Republic model as do the modified textures, which are by Anduril and Ghost.
The secondary hull is from Atrahasis's USS Declaration. As the Declaration is more often shown, in numerous fanon illustrations as being NCC-1031, I figured that it looks like a suitable predecessor to the classic Constitution secondary hull. I wanted the Horizon class to have a larger ship's stores and shuttle capacity than on later simpler starships.
The Impulse engine housing, on the Equinox, is from a reworked pod taken from the stock Taldren Klingon freighter in SFC 1. I know it looks crude close up but on SFC 1 unless one is piloting a shuttle or fighter past the ship, it doesn't notice that much in game.
A prediction is that somebody else will do a better version of these models, or a later version prior to conversion and upgrade to Constitution class.
The warp engines are reworked Moskva warp engines, taken from Sandman3d's Moskva. I've reworked them to match the style of numerous illustrations of pre-TOS warp engines in the period that the Horizon and Equinox appear, as opposed to just using ye stock TOS PB series warp engines. These took up most of the time spent on the project.
I've actually created quite a large number of models here. I made models of Donald Miller's pre-TOS old frigate and old Destroyer, which would have commisioned at the same time as the Texas class light cruiser, in the SFB timeline.
I'll put these up in another posting sometime.