I beg the indulgence of the forum if I took umbrage at
Lymans continued insistence that
post #52 the J58 is not a Ramjet, not a Turbo Ramjet, and not a Partial Ramjet...
I felt that once we could get Lyman to stop banging on with a fallacious argument the discussion could return to matters of fact, and teasing out why things might be as they are. I have a question of my own to follow.
peter kent provided the proof at post #12 that it is a "partial ramjet", and I pointed out that fact in my post #14. That particular posters are unable to accept iron clad proof I can only say they need to check their level of comprehension.
peter, re the 20 to 40% bleed figure. I came across the figure in a number of places, in particular one by Colonel Graham, so I give it some credence. Seems logical if you think about it, 20% when the bleed first opens at about Mach 2, increasing to 40% in the cruise as the increasing needs of the "ramjet" are met. I'll need to go back over the thread to tease out your other question/s that remain to be answered.
peter, edited to add re reduction in fuel flow with increasing speed.
Specific impulse is a way to describe the efficiency of rocket and jet engine. It represents the force with respect to the amount of propellant used per unit time. The higher the specific impulse the greater the efficiency. From the following ramjet formula you can see that the specific impulse (I
sp) is directly proportional to Mach (M
o).
