thank you very much for the research. blade is steel and hollow. quote
LIGHTNINGS AT WAR: P-38E / P-38F / P-38G
* The first Lightning to go to war was the "P-38E", which featured:
Improved instruments, electrical systems, and hydraulic systems.
New Curtiss Electric duraluminum propellers, though early P-38E production retained the older Hamilton Standard Hydromatic hollow steel propellers.