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How do you power a rocket engine?

everydayastronaut.com

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Re: How do you power a rocket engine?

#61

Post by avmich »

simne wrote: post #44

Very good article, but have few shortcomings. 1. Only first generations of "Soyuz" used H2O2 propellant, because it have very limited time before use (for "Soyuz", guaranteed 6 months), and because it have relatively high melting temperature. First chose H2O2, because "Soyuz" planned as independent ship, to fly relatively short missions around Moon (it is near impossible to withstand even 6 months in so small volume)…

Soyuz rocket uses 82% H2O2 for all first and second stage engines.

Soyuz spacecraft uses H2O2 for capsule control during reentry.

Soyuz spacecraft uses a variant of hydrazine fuel for orbital maneuvers.

All of this is true for all versions of Soyuz rocket (except Soyuz 2-1v) and Soyuz spacecraft, since 1950-s to today.

Re: How do you power a rocket engine?

#62

Post by speedylight »

showerst wrote: post #17
speedylight wrote: post #15

Earlier quoted context omitted.

Integza is one of my favorite channels of all time, his videos are always really informative and fun to watch. The only problem is he’s completely careless about safety—mainly by not wearing any protective gear for the exhaust fumes which include burned plastic.

I’m really torn on Integza. It’s a great channel and I love his spirit, but guys like that (and the teenagers that follow them) end up getting hurt or burning down their houses, which makes the news and gets new restrictions passed on all of us. Just a _little_ more nodding to safety would make him an awesome resource. Maybe safety culture in Portugal is different, but in the US he does tons of stuff that violates th…

You’re exactly right it would go a long way. Thankfully people in the comments do call him out on it so hopefully he’ll listen.

Re: How do you power a rocket engine?

#63

Post by Robotbeat »

master_crab wrote: post #26
panick21_ wrote: post #23

Earlier quoted context omitted.

Well, they are all chemical engines. We have no chemical engines that would work well for launching. In space we do use a lot of solar electric propulsion and lots other things that Goddard knew nothing about. Nuclear thermal propulsion could potentially be used but that has a whole host of issues where its not clear that its actually worth it compared to chemical. SpaceX Raptor is approaching pretty much the peak of…

“Well, they are all chemical engines. We have no chemical engines that would work well for launching.” I mean that’s what chemical engines are for. You aren’t launching off the ground with any of the electric based systems, and accidental radiation concerns have always hobbled nuclear engines. But, yes point taken on using them outside the atmosphere. However, they don’t improve our ability to launch manned missions…

> You aren’t launching off the ground with any of the electric based systems

Well… https://www.spinlaunch.com/

Re: How do you power a rocket engine?

#64

Post by wumpus »

simne wrote: post #44

Very good article, but have few shortcomings. 1. Only first generations of "Soyuz" used H2O2 propellant, because it have very limited time before use (for "Soyuz", guaranteed 6 months), and because it have relatively high melting temperature. First chose H2O2, because "Soyuz" planned as independent ship, to fly relatively short missions around Moon (it is near impossible to withstand even 6 months in so small volume)…

I've frequently read in news articles that the lifetime of the Soyuz spacecraft on orbit is limited by H2O2. You appear to be saying that's false.

A while ago I looked at Wikipedia and saw that the Soyuz spacecraft article didn't mention what the reaction control system uses for propellant.

Perhaps you can point at a source?

Re: How do you power a rocket engine?

#65

Post by avmich »

WalterBright wrote: post #30
master_crab wrote: post #18

For all the talk of SpaceX and a new race to Mars, no one seems to remark on the fact that rockets haven’t remarkably changed much since Goddard’s day. I remember asking one of my profs in college (an early researcher of the ramjet) what’s holding jet and rocket technology back. He said: melting point temps.

Haven't changed since Goddard? Oh my! Here's a list of the innovations the Germans made to Goddard engines in order to scale them up for the V2: 1. turbo-pump 2. building a jacket into the nozzle to both cool the nozzle and pre-heat the fuel 3. putting tiny holes in the jacket so the leaking fuel would form a boundary layer that would protect the nozzle from heat 4. baffles in the combustion chamber to damp out pogo-…

> The Saturn V engines were scaled up V2 engines.

That's very debatable :) - everything is everything else, if squinting hard enough. Just an injector head of F-1 was a serious R&D topic, with whole methods of experiments invented.

Re: How do you power a rocket engine?

#66

Post by WalterBright »

avmich wrote: post #65
WalterBright wrote: post #30

Earlier quoted context omitted.

Haven't changed since Goddard? Oh my! Here's a list of the innovations the Germans made to Goddard engines in order to scale them up for the V2: 1. turbo-pump 2. building a jacket into the nozzle to both cool the nozzle and pre-heat the fuel 3. putting tiny holes in the jacket so the leaking fuel would form a boundary layer that would protect the nozzle from heat 4. baffles in the combustion chamber to damp out pogo-…

> The Saturn V engines were scaled up V2 engines. That's very debatable :) - everything is everything else, if squinting hard enough. Just an injector head of F-1 was a serious R&D topic, with whole methods of experiments invented.

Obviously there was a lot of refinement and development going on in those engines.

For another example, the Ohain axial flow turbojet is quite recognizable even up to modern jet engines. The Whittle radial flow turbojet was a dead end.

Innovations 1..3 are all revolutionary, not evolutionary, advances in rocket engines. 4 maybe is.

https://airandspace.si.edu/collection-objects/v-2-rocket-eng...

The Saturn V engines needed much more powerful turbopumps, and so used a secondary rocket engine just to drive the pump. How cool can you get?

Re: How do you power a rocket engine?

#67

Post by hydrogen7800 »

mLuby wrote: post #22
hydrogen7800 wrote: post #19

Earlier quoted context omitted.

Expert here. I'm a longtime lurker on HN, but registered just for this comment. I design aerospace pressure vessels for a living. As showerst alluded to, there are often things called "propellant management devices" or PMDs. There are a few reasons these might be used. In zero G, you need the propellant sump to remain wetted with propellant; it would be bad to ingest the pressurant/ullage gas into your engines. Some…

Love how much expertise there is here; thanks for adding yours! When you say "metal bladder/diaphragm" is that a sliding wall with propellant on one side and pressurant on the other? (I can't imagine how the seals in that would work.) Or do you mean the metal actually deforms in place?

Yeah, the metal deforms. They are single use devices. Imagine a spherical metal tank, with a thin metal hemisphere welded inside. The hemisphere would invert as the propellant is expelled. Hard engineering and manufacturing problems here. I think there have been piston tanks (which would be reusable with sliding elastomer seals. Not many elastomers play well with hypergolics), but they would be very weight inefficient.

Re: How do you power a rocket engine?

#68

Post by panick21_ »

WalterBright wrote: post #30
master_crab wrote: post #18

For all the talk of SpaceX and a new race to Mars, no one seems to remark on the fact that rockets haven’t remarkably changed much since Goddard’s day. I remember asking one of my profs in college (an early researcher of the ramjet) what’s holding jet and rocket technology back. He said: melting point temps.

Haven't changed since Goddard? Oh my! Here's a list of the innovations the Germans made to Goddard engines in order to scale them up for the V2: 1. turbo-pump 2. building a jacket into the nozzle to both cool the nozzle and pre-heat the fuel 3. putting tiny holes in the jacket so the leaking fuel would form a boundary layer that would protect the nozzle from heat 4. baffles in the combustion chamber to damp out pogo-…

> The Saturn V engines were scaled up V2 engines.

I mean, not really. They were a totally different cycle type. Different fuel. Different way adjusting trajectory. Different injectors.

Seems pretty different to me.

Re: How do you power a rocket engine?

#69

Post by mateo1 »

pontifier wrote: post #52

I've often wondered if "gravity feed" might be an option. In a tall liquid fueled rocket, Gravity, then thrust, could create arbitrarily high pressures at the nozzle if the column of fuel is tall enough.

Well, I guess is is possible, but to get 100 bar at 1g you need a 1km+ column. At higher accelerations though it's not such a bad idea.

Re: How do you power a rocket engine?

#70

Post by WalterBright »

panick21_ wrote: post #68
WalterBright wrote: post #30

Earlier quoted context omitted.

Haven't changed since Goddard? Oh my! Here's a list of the innovations the Germans made to Goddard engines in order to scale them up for the V2: 1. turbo-pump 2. building a jacket into the nozzle to both cool the nozzle and pre-heat the fuel 3. putting tiny holes in the jacket so the leaking fuel would form a boundary layer that would protect the nozzle from heat 4. baffles in the combustion chamber to damp out pogo-…

> The Saturn V engines were scaled up V2 engines. I mean, not really. They were a totally different cycle type. Different fuel. Different way adjusting trajectory. Different injectors. Seems pretty different to me.

Different cycle type? I'm interested - what's different?
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