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Comment by idlewords | Hacker News Reader

The second stage of New Glenn just reached orbit, fate of the first stage (which attempted a re-entry burn and soft landing) is unknown.

I'm curious about the thrust/weight ratio of this rocket. It seemed to really take its time clearing the tower and getting to 10,000 feet. Is it possible they're running the engines at reduced thrust for this first launch?

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Looks like they lost the booster

It will turn up.

Might be, but those shock diamonds are not a great sign for their nozzles despite being beautiful

> Might be, but those shock diamonds are not a great sign for their nozzles despite being beautiful

Shock diamonds do not determine nozzle health/stability. The diamonds themselves are 100% part of nominal operation.

What you're looking for is flow separation from the nozzle because it's under expanded leading possible instability. Scott Manly did a great bit on it[0].

[0] https://youtu.be/l5l3CHWoHSI?t=261

Shock diamonds are normal for first stages. Unless you're smarter than BO/SpaceX/ULA engineers and want to tell us more, I call BS on your post.

Could you elaborate on that? Why would the exhaust reflecting off the shock wave cause damage to the nozzle?

I don't think it implies damage, but it implies that the exhaust pressure is lower than the outside air pressure (which you would not want for perfect efficiency). That's normal though because the first stage operates in a wide range of pressure, and you can only adjust it for one exhaust pressure. So mach diamonds on liftoff should be normal.

Mach diamonds are absolutely normal and expected. Not sure what GP is talking about.

Maybe he means the New Glenn should have had aerospike engines.

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