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The Tech Behind SpaceX’s New Engine

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Re: The Tech Behind SpaceX’s New Engine

#11

Post by CarVac »

twic wrote: post #8

Either approach, whether it recaptures the oxidizer or fuel rich preburner exhaust, is clearly an improvement over dumping everything overboard. But neither is an ideal solution as there’s still potentially combustible products being wasted. Are there? Here's a diagram of the RD-180, which uses an oxygen-rich preburner: https://en.wikipedia.org/wiki/RD-180#/media/File:Rd180schema... Where is anything escaping other t…

There's no wasted propellant with normal staged combustion.

But full flow staged combustion lets you fully vaporize both propellants before they mix, leading to more optimal burning.

Re: The Tech Behind SpaceX’s New Engine

#12

Post by twic »

kumarvvr wrote: post #6

This is an excellent article. Just curious, how much more efficient is the full-flow engine? And, what exactly is the deal with the seals the article is talking about? Anyone have more info?

I think this is about safety. You need two pumps, one for fuel, one for oxygen. The compressor side of the pump will be full of whatever it is you're pumping. But if you use a single type of preburner, then the turbines of both pumps are full of either hot fuel gas, or hot oxygen gas. That means you have one pump where you have hot fuel or oxygen right next to cold oxygen or fuel. If the seals leak, the pump blows up.

Re: The Tech Behind SpaceX’s New Engine

#13

Post by ceejayoz »

twic wrote: post #8

Either approach, whether it recaptures the oxidizer or fuel rich preburner exhaust, is clearly an improvement over dumping everything overboard. But neither is an ideal solution as there’s still potentially combustible products being wasted. Are there? Here's a diagram of the RD-180, which uses an oxygen-rich preburner: https://en.wikipedia.org/wiki/RD-180#/media/File:Rd180schema... Where is anything escaping other t…

Scroll one paragraph down from that quote and the RD-180's approach is mentioned.

> In the 1950’s, Soviet scientists came up with something of a compromise. Instead of using a fuel-rich mixture in the preburner which produced an exhaust that couldn’t be safely recirculated into the engine, they experimented with running the preburner oxygen-rich.

> Eventually the Soviets mastered the metallurgy required to build the turbine and developed several engines that operated on the oxygen-rich preburner concept. The exhaust was piped into the engine’s combustion chamber and recovered at least some of the propellants which would otherwise have been dumped overboard. The modern day Russian RD-180 engine, currently in use by the American Atlas V, is a continuation of this technology.

Re: The Tech Behind SpaceX’s New Engine

#14

Post by FrojoS »

clanrebornsx wrote: post #5
russellbeattie wrote: post #4

If you live in SoCal (or even if you're just visiting), definitely take a quick trip by the SpaceX facilities in Hawthorne [1] where they have a Falcon rocket sitting outside. From a distance it looks like and industrial chimney, but as you pull up, you can see it's an actual rocket. Standing next to it gives a great sense of scale the next time you're watching a SpaceX video. 1. https://www.google.com/maps/place/Spa…

I work there as a Janitor, the one u see is the fake rocket basically.

Fake? Isn't it the first stage that ever landed!?

Re: The Tech Behind SpaceX’s New Engine

#15

Post by kiba »

maneesh wrote: post #7
kiba wrote: post #2

I don't like the usage of 'impossible'. Impossible by what standard? Laws of physics forbidding it is understandable. We may likely never see the development of FTL because our understanding as we know it would see it impossible to do due to its strange implication about cause and effect.

someone didn't read the article, or notice the quotes around the word "Impossible"

There wasn't quotes around 'impossible' in the article.

Re: The Tech Behind SpaceX’s New Engine

#16

Post by [deleted] »

twic wrote: post #8

Either approach, whether it recaptures the oxidizer or fuel rich preburner exhaust, is clearly an improvement over dumping everything overboard. But neither is an ideal solution as there’s still potentially combustible products being wasted. Are there? Here's a diagram of the RD-180, which uses an oxygen-rich preburner: https://en.wikipedia.org/wiki/RD-180#/media/File:Rd180schema... Where is anything escaping other t…

[deleted]

Re: The Tech Behind SpaceX’s New Engine

#17

Post by CabSauce »

kumarvvr wrote: post #6

This is an excellent article. Just curious, how much more efficient is the full-flow engine? And, what exactly is the deal with the seals the article is talking about? Anyone have more info?

Scott Manley has done a few videos (youtube) recently around rocket architecture; including several videos about the Raptor engine. Well-worth checking out. (I don't have a link at the moment, sorry.)

Re: The Tech Behind SpaceX’s New Engine

#19

Post by buboard »

its not impossible, considering that both the US and the russians built them (but never flown). These articles usually go overboard with the hero-worship and fail to mention that those are incremental improvements on the immense rocketry feats of the 60s.

Re: The Tech Behind SpaceX’s New Engine

#20

Post by JumpCrisscross »

“Benefits of the full-flow staged combustion cycle include turbines that run cooler and at lower pressure, due to increased mass flow, leading to a longer engine life and higher reliability.”

TL; DR Full flow lowers turbine temperatures at the expense of parts complexity. Given turbopumps are the devil’s ass part of rocketry, this has been a sought-after technology. The pay-off isn’t so much efficiency as much as longevity. (This also explains why full flow hasn’t been a priority for anyone until SpaceX.)

https://en.m.wikipedia.org/wiki/Staged_combustion_cycle#Full...

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