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A comment on Hypersonic HAWC missile flies, but details are kept hidden. Parent comment

Re:Hypersonic HAWC missile flies, but details are kept hidden by ethbr0 on Tuesday September 28, 2021 @07:39PM (#28688719)
Rocket engines require onboard oxidizer (or equivalent), so you have to carry a substantial additional amount of mass along with you.

Air-breathing engines are able to save all that mass by using atmospheric oxygen.

This matters, because it's the rocket equation in reverse: no onboard oxidizer = lighter vehicle = less fuel needed = even lighter vehicle = longer range / more payload

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Re:Hypersonic HAWC missile flies, but details are kept hidden by rektide on Tuesday September 28, 2021 @08:20PM (#28688972)
this is a good queue-in to start talking about mass ratio: the ratio of weight that is dedicated to payload versus the weight of the delivery platform and it's fuel (slightly simplified take).

this device is almost certainly air breathing. there's simply too big an oxygen-breathing-demand at speed to do anything else for sustained high speed flight, where you need to be generating a lot of motive force.

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