U-2A / U-2B / U-2C engine and inlets

I am researching early U-2 versions, and I bumped into something strange. All my sources (Aerograph, In Action, Blackbirds, various websites) report that:

- the U-2A had the J57-P31A engine

- the U-2B had the J75-P13 engine using the same inlets as the U-2A

- the U-2C had the J75-P13B engine and much inlarged inlets

I always found the combination of J75 and small inlets strange, I wouldn't expect that the mass flow would match. But each and every source says the B had the J75. That is, until I found a document on the CIA website called "The CIA and the U-2 program, 1954 - 1974", dated 1998:

On page 95 (page number, not Acrobat's page count), the report says that the original engine of the U-2A was replaced by the J57-P31 in 1956, creating the U-2B. Pages 149 and 152 report the installation of the J75-P13 engine in 1958-1962, creating the U-2C. Whether the inlets were enlarged is not mentioned by the way.

Who is right here?? The CIA version makes more sense to me, but it stands alone. Are my other sources possibly outdated (they are all some 15 years old) ?

Rob de Bie

PS: The document contains numerous other juicy bits, like maps of Russian and Cuban overflights (p107, p202), the steadily decaying number of Agency U-2's (p251 reports 6 left in 1966, of the 20), the blue-black color (p149), etc. Recommended!

My models:

Me 163B site: