Theory on lift

[peter kent]

the J58 was not a turboramjet (TR)

Hi Italia,
Don't know if you are still receptive to getting to grips with the J58 as it's been a while since your June post. I don't believe anyone followed up on your points.
Incidentally, Ryman had already correctly killed the TR.
Some of the information in the sources you are referencing is wrong, including classifying the J58 as a TR, unfortunately. One source will reference another source and misunderstandings/errors get perpetuated despite their dedicated authors.

TR was probably coined by someone because it sounded more exotic than bypass bleed engine (which is what P&W called it). They had to fit Mach3's worth of impressive ram into the name somehow.

What follows only needs to look at the engine airflow, not the very significant airflow which goes around the engine and causes so much interest in the intake and exhaust thrust contributions.

First we'll see how similar the airflow is to that in a familiar Mach2-type military turbofan or bypass engine. Then we'll see the reason why it could never have been a TR.

Going one step at a time thro each engine, an F100 at Mach2 say, and the J58 at M3.

F100: all the air destined for the engine goes thro its first compressor, also called the fan.
J58: all the air destined for the engine goes thro the 1st 4 stages of its only compressor

F100: some of the fan exit air goes down the engine bypass duct, the rest goes thro its 2nd compressor ( and combustor and turbines)
J58: some of the 4th stage exit air goes down the 6 external engine bypass or bleed tubes, the rest goes thro the remaining 5 compressor stages (and combustor and turbine)

F100: the engine bypass air mixes with the turbine exit air upstream of the afterburner fuel manifolds
J58: the engine bypass air mixes with the turbine exit air U/S of the A/B fuel manifolds

These air paths are for all intents and purposes identical. If you wanted to classify the two engines you could even put them in the same drawer but it wouldn't have TR on the label. After the above you may wonder what was so special about the J58. Apart from the huge challenges overcome with materials, etc. it was different to an F100 type at lower speeds though because the bleeds were closed. So it had a bypass ratio varying from zero at low speeds to some higher value at cruise. This variable bleed made it unique. An F100 BPR just varies a bit about some nominal value.

The TR could have been, on paper at least, but it wasn't as the following shows (ref 'The Engines of Pratt&Whitney' by Jack Connors).
Early versions of the J58 were a plain afterburning turbojet (shown on many web photos).P & W converted it for M3 cruise by adding 6 bypass bleed ducts from the middle of the compressor to the turbine exit (shown on many web photos).
Alternatively, it could have been modified with blocker doors to close off the compressor inlet and a big annular passage around the engine for the ram air which would discharge into a common afterburner. So here, finally, is your TR, but it never happened because it would have been more mechanically complex and heavier. The bleed tubes were a much more elegant solution by virtue of their simplicity. They did the job.
The crucial insight here is you can't turn a turbojet into a TR just by adding a few bypass tubes.

Not wishing to belabor a point, an authoritative source on ramjet configurations (avail on the web) is 'A century of Ramjet Propulsion Technology Evolution' by Ronald S. Fry.
And for the jet engine an equal mine of essentially first-hand, and therefore accurate, information (avail on the web) is 'Gas Turbine Technology Evolution' by Bernard L. Koff.

I hope you have found the above of some value.