OldBUFFkeeper
Though having arrived "late to the dance"
Don't worry, I'm very happy to see a reply.
For openers, specs, especially physical dimensions, on both(!!) the J58 and the J91 seem to be almost imossible to come by.
The J91 had an inlet diameter of 54" or 55". From what I was told the pre-bypass J58 had a diameter of 47" (which I assume is the inlet diameter)
Bought a copy of "Advanced Engine Developement at P&W", and found only passing refernce to the J58, and nothing about its immediate predecessor, the J91, let alone the sole reason I bought the book, i.e. the JTF-17 duct-burning turbofan that was offered for the L-2000 SST.
I don't have much information on the JTF-17, though I used to know more (my memory isn't perfect). From what I remember it had a 3-stage fan, a 6-stage HP compressor, and a bypass-ratio of 1.3 with the afterburner only in the fan-duct. I do remember the engine design being relatively compact in overall design, and had no inlet guide-vanes (like modern commercial turbofans).
There was a plan to create a turbo-fanned J58, early for Lockheed's L-2000 design, but the design was not developed for one reason or another.
If you want any information on the L-2000, I have considerably more (though not absolute).
Also curious about the "80% scale down" of the J58 from the J91. Was that a direct linear reduction or overall mass? Saw one quote where the J91 diameter was cited as "72(!!!) inches), a figure only reached by the AB nozzle of the GE-4 for the Boeing 2702 SST.
I'm not sure if the scale-down was in terms of mass-flow, or in terms of overall size. Regardless, when it comes to the listed-diameter, sometimes this means the diameter of the engine at it's widest point, not the inlet diameter.
In short, any info on the J91 or the J58 would be most appreciated!. Even directions to reference sources would be good.
Agreed.