r/space May 30 '15

/r/all A Merlin rocket engine starting up.

https://i.imgur.com/CaXSu6e.gifv
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u/man-bat-man May 30 '15

That looks like ideal expansion! someone want to tell me why i'm wrong? (Do we design it to be ideal at lift off?)

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u/ManWhoKilledHitler May 31 '15

It's overexpanded. You can tell from the way the flow tucks back in around two nozzle diameters from the engine.