In mid 50s Iberia decides to patron a project of an airliner to fly Madrid - Buenos Aires, non stop (10.050 km). CASA and INTA as technology partners design a 4 radials plane strongly influenced by DC-7, called INTA-40.
Here you can see INTA-40 along with its inspiration: DC-7C and INTA-20, which you can see in the thread devoted to CASA transports and liners. All of them in constant scale.
Designer's main interest was range. Fuselage is depper than DC-7's, allowing for tankage in belly area; besides this, it carries wing tips tanks. Accomodation is lower than DC-7's, but with more confort.