#c-57d

[chernobog13]

The Monster From the Id as it attacks the crew of the C-57D in Forbidden Planet (1956).

[atomic-chronoscaph]

C-57D landing on Altair IV - Forbidden Planet (1956)

[spockvarietyhour]

United Planets Cruiser C-57D, landing on Altair IV.

[chernobog13]

The crew of the United Planets starship C-57D armed and ready!

What they're battling against!

[chernobog13]

"As you can see, the doohickey is connected to the whatchamacallit by means of this gizmo."

Chief Quinn (Richard Anderson) uses some sophisticated techno-babble while speaking to Commander J.J. Adams (Leslie Nielsen) and Lieutenant "Doc" Ostrow (Warren Stevens) in Forbidden Planet (1956)

[chernobog13]

Inside the C-57D from Forbidden Planet (1956).

[chernobog13]

Commander J.J. Adams (Leslie Nielsen) takes over the controls of the Starcruiser C-57D for the final approach to the Forbidden Planet (1956).

[chernobog13]

A schematic of the United Planets Cruiser C-57D from Forbidden Planet (1956) by Jon C. Rogers.

From scenes inside the ship from the film, as well as fan-made blueprints that have been made, the C-57D is pretty cramped. I would say it's on par with World War ll-era submarines or other smaller naval vessels from that time.