This equates to an unprecedented 17.6:1 deep-throttling capability, which means this cryogenic engine can quickly throttle up and down.
这相当于达到了空前的17.6:1深度节流能力，意味这台低温发动机能快速控制节流。
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Needle valves are a small (usually 1 inch or less), simple, and rugged means of throttling and shutting off extremely high pressures compared with other valves.