Matt Jeffries
Art Director Matt Jeffries was a bomber pilot during WWII, and he based the Enterprise’s letters “NCC” on 20th-century aircraft registration codes. The “N” represents an aircraft registered in the United States. The first “C” represents a civil aircraft, and he added a second “C” simply because he thought it “looked neat.”
Source: Squir
The Enterprise’s “Jefferies Tubes” were small corridors or tunnels that gave access to critical starship systems. They were named after Matt Jeffries, who designed the original starship Enterprise.