Okay folks, to stop derailing Captain Robert April's thread for a reimagined Daedalus here, I've decided to start my own thread.
This project is part of a larger project I began a few years back to try to tie 'Star Trek: Enterprise' more into the mainstream canon, beginning with figuring out how the NX-01 fits into the lineage. I had more or less backburnered it for a good long while until CRA's thread got me thinking about the Icarus, since our ideas were so similar.
I must preface this by saying that my Icarus meant to be the Galaxy to the Daedalus's Nebula in some ways - it's a bigger, more ambitious project that is based on the same developments and ultimately in my timeline is less than a total success. It was developed after the Romulan War as a replacement for the NX class and similar prewar ships in the years before the overly-ambitious Warp Seven Project (mentioned briefly in 'TATV') could be achieved. I place this achievement with NX-1100, more on that later.

And here's a little writeup from way back describing the ship. It needs revision, since my ideas have changed somewhat and are reflected in the sketch.
I'd really appreciate everyone's feedback... I know it's difficult to get a full picture without reading the entire evolution, which I can post if need be, but it's kind of long and I'm currently most interested in your thoughts on the design of Icarus and what direction I should take it, what logical features it should keep from the NX, whether I should give it a neck, and so on.
This project is part of a larger project I began a few years back to try to tie 'Star Trek: Enterprise' more into the mainstream canon, beginning with figuring out how the NX-01 fits into the lineage. I had more or less backburnered it for a good long while until CRA's thread got me thinking about the Icarus, since our ideas were so similar.
I must preface this by saying that my Icarus meant to be the Galaxy to the Daedalus's Nebula in some ways - it's a bigger, more ambitious project that is based on the same developments and ultimately in my timeline is less than a total success. It was developed after the Romulan War as a replacement for the NX class and similar prewar ships in the years before the overly-ambitious Warp Seven Project (mentioned briefly in 'TATV') could be achieved. I place this achievement with NX-1100, more on that later.

And here's a little writeup from way back describing the ship. It needs revision, since my ideas have changed somewhat and are reflected in the sketch.
I'm working on an update sketch, which I then plan to develop into full drawings, and from there probably the rest of the project. Not shown are the forward notch for the deflector, the saucer impulse engines, the 'rib' structure similar to those on the Daedalus study model, and most of the other detailing. Among changes I'm making are making the secondary hull struts at 45 degrees to the centerline, but keeping the nacelle struts angled. I'm not entirely sold the twin sets of pylon configuration... an alternate idea would be to retain both sets of struts to the nacelles, but only the rear secondary hull struts, replacing the forward struts with a small neck. My main goal is to keep the hangar out of the secondary hull. From an evolutionary standpoint, I want to have that come from the Daedalus.Icarus
Like the Warp Five Project before it, the Warp Seven would push the barriers of superluminal flight. However, the project would take years to complete, and in the meantime Starfleet needed a replacement for the NX series at the forefront of Starfleet missions. Daedalus certainly didn’t fit the need, so it was back to the drawing board at San Francisco Yards. In many ways, Icarus was the ship that Starfleet would have built if they’d been allowed to go further with the NX design in the first place. In others, she was a completely unique ship. The basic design had been just a sketch on the drawing boards since just before the outset of the Romulan War. Now Starfleet had the opportunity to pick up where they left off. Icarus was a clear mid-step in starship design, occurring post the Warp Five Program work but before the Warp Seven Project redefined Starfleet shipbuilding. Icarus’s heritage from both the NX and Daedalus was readily apparent, but she was also a sign of what was coming. Shewas simpler and somewhat more advanced than NX, but sturdier and more elegant than Daedalus. The Icarus series became one of the earliest emblems of the infant Federation. The U.S.S. Icarus (NCC-400) was launched in 2175.
In shape, the Icarus borrowed heavily from the design of the NX class, but incorporated a twin hull design akin to the Daedalus. Her primary hull was a somewhat bulbous saucer evocative of the NX, with a twin catamaran necks extending aftward to support twin nacelles and a tapered cylindrical secondary hull evocative of that of the Daedalus that housed the warp reactor, a modernized version of the kind found in late Daedalus class ships. Narrow corridors provided transit through the catamarans to the secondary hull for the engineering personnel as necessary. Icarus’s nacelles were similar the NX type, but were more sturdy and approximately twenty percent larger. Like the Daedalus and all modern ships of the period, they mounted needle-like field probes at the forward tips of the nacelles. The ship featured a combined vertical/horizontal launch bay similar to that found on the NX series at the aft of the saucer.
Despite not being designed specifically for combat, the class was well-armed. The Icarus class ships were the first Starfleet ships to rely on energy shields for primary defense. They mounted multiple torpedo launchers and pulse cannons. Phase cannons, which prior to the war had been field-tested on NX class ships such as Enterprise, proved impractical for widespread use after the war. It was only in the 2250s, when the modern phaser was developed, that Starfleet would implement the widespread use of phased energy weapons. Similar was true for the relationship between photonic and photon torpedoes; it seemed both phase cannons and photonic torpedoes were ahead of their time. The Icarus mounted a large combined sensor/deflector at the front of the secondary hull that was the most advanced of the time. The design also retained a main forward sensor/deflector in the NX deflector position. This basic configuration would be retained through the Excelsior class. The Icarus’s advances also included a full, multi-pad transporter chamber.
The Icarus class also saw the first successful, if improvised, primary/secondary hull separation, a design feature that would become a staple safety feature in later Starfleet ships. The U.S.S. Galaxy faced an imminent antimatter containment failure that would have destroyed the ship and killed the entire crew. In a stroke of genius, the Captain and Chief Engineer devised a plan to use torpedo warheads to destroy the catamarans connecting the primary and secondary hulls, then use the impulse engines on the primary hull to rocket away from the secondary hull before containment failed. It was a race against time, but the plan was successful. All subsequently built members of the class featured the separation plan in their design, mounting torpedo warheads in the neck corridor. Over seventy of the class was built. The last Icarus class ship was decommissioned in 2215. The primary hull of the Galaxy now resides in the Fleet Museum, alongside the fully restored Icarus-class U.S.S. Yorktown.
I'd really appreciate everyone's feedback... I know it's difficult to get a full picture without reading the entire evolution, which I can post if need be, but it's kind of long and I'm currently most interested in your thoughts on the design of Icarus and what direction I should take it, what logical features it should keep from the NX, whether I should give it a neck, and so on.