Since starting this topic, which generated a lot of discussion on the relevance of ramjet terms in describing the engine, I've done a lot of digging so why keep it to myself when a few of you showed interest in applying various partial/turbo/ramjet appellations. The question I set myself was "Is there anything unique about the J58 installation which warrants any ramjet term?"
Brian in an early post identified the Lockheed-originated "It's a ramjet" from KJ. KJ didn't give an explanation though. I now know that he wasn't interested in the workings of the engine, not surprising with the weight he carried on his shoulders. I have just bought his book "Kelly, More Than My Share of It All". Quote "..bypassing the high compressor..and flying as a ramjet....with no machinery obstructing the flow...". I think it's worth pointing out this red herring because it could well be the mother that spawned the most common 'understanding' out there.
(P&W documentation tells us 80% of what went into the afterburner was turbine exhaust. About 13% was cooling air from the compressor and 7% was compressor air for burning)
As a baseline for judging uniqueness I used the only other flight-tested afterburning turbojet installation we know about which was designed for Mach 3, the J93 in the Valkerie.
What happened to the air going through the intakes and ejector nozzles was much the same. In both compressors the air hit all the blades at the right angles, despite running at design 100% mechanical RPM and very high inlet temperature. The afterburners were a bit different though as the J58 was the forerunner of high boosts seen in future fan engines, with cooling air cooler than EGT and reduced EGT at entry.
Is this significant? Well we know the machinery was a drag item at cruise, ref D.Campbell's "F-12 Series Aircraft Propulsion System Performance and Development". And just noticed another reference to this in "SR-71 Revealed" quote "at cruise the rotor of the engine actually had a small negative thrust load on the engine" (I wont quote the sentence before that
). So it seems that the J58 had just gone over the edge of conventional operation with the afterburner now assuming a greater relative importance than ever before, even making up for a thrust shortfall from the machinery. This could well be what makes it unique. The Valkerie wasn't there yet with its still-positive epr (stick my neck out with fig3 pumping characteristics
Emission Measurements of a J93 Turbojet Engine )