A Enterprise-B é uma classe Excelsior :
A Enterprise-D é uma classe Galaxy :
A Enterprise-C é uma turma de Embaixadores que supostamente representa um projeto de transição entre a classe Excelsior e a classe Galaxy. Aqui está o conceito original com uma seção de acionamento / casco secundário muito diferente que parece um cruzamento entre as seções de direção do Galaxy e do Excelsior:
O artigo da Memória Alfa sobre o modelo de classe Ambassador explica que o modelo final de estúdio foi criado por Greg Jein. em um projeto que Rick Sternbach desenvolveu a partir do conceito original de pintura e design de Andrew Probert. O conceito original tinha linhas mais orgânicas e curvas suaves, parecendo muito mais uma mistura das classes Excelsior e Galaxy. Mas foi simplificado por causa das limitações de tempo impostas pela "Empresa de ontem":
Fonte:
The studio model was designed by Rick Sternbach, based on sketches as well as on a design concept painting produced by Andrew Probert for the first season of Star Trek: The Next Generation. The design was intended to suggest an intermediate step between the Excelsior-class and the Galaxy-class starships. A relief sculpture of Probert's design was placed in the observation lounge aboard the USS Enterprise-D. Unfortunately, the model was needed for "Yesterday's Enterprise" much sooner than the time it would take to fabricate the smoother lines of Probert's concept, requiring Sternbach's alterations which ended up on Greg Jein's final model. As Sternbach later renumbered, elaborating in detail on his thought processes,
"The deadline for sketching and blueprinting the Ent-C was pretty normal in that I had a few days preproduction to sketch up the ship as first suggested in Andy Probert's color painting, get it approved as an intermediate shape between the Excelsior and the Galaxy classes, and then work up the blueprints. Greg Jein was given the miniature job, as we know. I suppose it took about three or four days to draft up the hull shape. The port elevation sketch was the first and, ultimately, the only sketch view of the Ambassador class Enterprise-C done for the TNG episode "Yesterday's Enterprise." Time constraints dictated that the blueprints and filming miniature be started as soon as possible, and the general look of the ship was quickly approved.
"The genesis of the design came from a small color painting done by Andy Probert back in the early preproduction for Season 1, plus a mental blending of the Excelsior/Enterprise-B and Galaxy class Enterprise-D. While Andy's color sketch showed an elliptical cross section for the engineering hull and an intended elliptical saucer (not clearly visible but confirmed by Andy), the Enterprise-C would require some simplifications if it were to be constructed in time for filming. I began drawing up the blueprints with a circular saucer and a circular cross section for the engineering hull, knowing that they would make model maker Greg Jein's job markedly easier. Swinging compass arcs for the major saucer thickness changes and secondary hull bulkheads took much less time in the drafting stage than calculating ellipses, which is not impossible with pencil and tracing vellum (using something called the trammel method), just tedious. With the basic line work completed for a combined top/bottom view and a fore/aft view, all of the expected details on a Starfleet ship were added. Shield grid lines, phaser strips, lifeboat hatches, reaction control thrusters, running lights, engineering access hatches, and windows populated the surface.
Esboços de design de Sternbach: