Pressurized cockpits and fuselages question

[chris ballance]

In the early 1940s what were the major technical barriers to building aircraft with pressurized cockpits and fuselages? The structural stress/design, fabrication problems, materials and weight, seals, compressors/turbochargers?

 

[FLYBOYJ]

In the early 1940s what were the major technical barriers to building aircraft with pressurized cockpits and fuselages? The structural stress/design, fabrication problems, materials and weight, seals, compressors/turbochargers?

Basically all the above, but the magic bullet was the development of a practical outflow valve(s).