J-58 engine test (of the A-12 and SR-71) full-afterburner at sea level. They produced way more thrust at 80,000 ft where the atmospheric pressure was .5 PSI up there, compared to 15 PSI ambient pressure here. - Upgoat

J-58 engine test (of the A-12 and SR-71) full-afterburner at sea level. They produced way more thrust at 80,000 ft where the atmospheric pressure was .5 PSI up there, compared to 15 PSI ambient pressure here.
submitted by Boardallday3 to Aircraft 1.6 yearsSep 11, 2022 01:44:55 ago (+4/-0) (youtu.be)
https://youtu.be/z-PVmtJ0HpU

[ - ] SweetChicken 0 points 1.6 yearsSep 11, 2022 08:08:59 ago (+0/-0)

Talk to me Goose

[ - ] usedoilanalysis 0 points 1.6 yearsSep 11, 2022 05:42:53 ago (+0/-0)

You need something like 64:1 pressure ratio to go above Mach 3. The J58 engine couldn't use the ramjet system until about Mach 1.6. Without it, the J58 produced around 16 bar. The F22 engine produces 22 bar. With the ramjet system the J58 produced nearly 30 bar. With nearly 70x less backpressure at altitude 30 bar produces that 64:1 ratio.

The ramjet system uses supersonic compression waves to basically supercharge the engine. Cool stuff, and nothing like that has ever been used on a plane since. Kelly Johnson was a man ahead of his time.

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