Talk:Staged combustion cycle

FYI
to whomever made the picture:

The oxidizer is always the green color, coming in from the top right of the schematic. The fuel is always shown in red, coming in from the top left of the schematic. And usually, either ALL of the fuel (fuel rich) or the oxidizer (ox. rich) gets fed into the Pre Burner.

Just letting you know ...

192.146.217.215 19:29, 20 July 2007 (UTC) Aerojet Engineer


 * Thanks for the tip. Could you show me some examples of that convention? The first link I went to didn't have green oxidizer or a left fuel entry. I'll certainly update the images if it is a convention.


 * Also, all of the fuel _does_ go through the preburner in the schematic. Did you confuse the second image (FFSCC) with the first image (Staged combustion)? --Duk 20:29, 20 July 2007 (UTC)


 * Also, who ever made the picture spelled the word Exchanger wrong. It is spelled "Exanger" in the photo. — Preceding unsigned comment added by 174.88.243.130 (talk) 16:18, 24 February 2013 (UTC)

NK-15
Shouldn't the honors for being the first closed cycle engine go to the NK-15 and not it's descendant (which never actually flew on the N-1, by the way)? 209.244.31.35 (talk) 23:26, 18 April 2008 (UTC)


 * I believe the first closed-cycle engine was the 11D33, built by Melnikov in OKB-1 for the 4th stage (Block-L) of the Molniya rocket. There is a reference to this in the book _RKK Energiya 1949-1999_. DonPMitchell (talk) 05:26, 9 May 2008 (UTC)

Deemed impossible -- when?
Staged combustion cycle (rocket) states that "In the 1990s, ... Kuznetsov shipped an engine to the US for testing. Staged combustion had been considered by American engineers, but deemed impossible." The Space Shuttle main engines, however, use staged combustion and they first flew in 1977. Does anyone here have access to the source, "Cosmodrome History Channel, interviews with Aerojet and Kuznetsov engineers about the history of staged combustion," to clarify this. -- Thinking of England (talk) 02:24, 6 July 2009 (UTC)


 * It was because of the high temp/pressure oxygen in these engines. The russians used oxidiser rich, hot, gas flows, but the metallurgy of the pipes and so forth gets interesting when you do that.- (User) Wolfkeeper (Talk) 02:57, 6 July 2009 (UTC)


 * So was it the particular style of staged combustion (using oxygen-rich preburners) that American engineers had deemed impossible? As it is presented now, the article seems to imply that they considered staged combustion in general to be possible only after they tested the NK-33 in the 1990's, but as indicated in the article, the SSMEs (first flying in 1977) uses staged combustion.  I wish I could find a transcript of that show in order to see the actual quote and its context. --  Thinking of England (talk) 05:07, 6 July 2009 (UTC)

Thanks 128.8.238.167 for clarifying this. -- Thinking of England (talk) 00:12, 20 July 2009 (UTC)

A large portion of this article is flat-out incorrect. Pratt & Whitney built a series of hydrolox staged combustion engines during the 1960's in preparation for what they expected would be a series of space shuttle contracts. John Chamberlain independently thought of staged combustion during Pratt's work in the 1950's on the RL-10 as a way to increase chamber pressure (See "Advanced Engine Development At Pratt & Whitney", Dick Mulready, 2002). NASA hyped the difficulty of the SSME heavily in the 1970's because of Rocketdyne's delays, and the idea that nobody in the USA had ever done it before became accepted belief. Voronwae (talk) 06:14, 1 February 2018 (UTC)


 * Oxygen (oxidizer) rich staged combustion was "deemed impossible". As mentioned before, the SSME flew in 1977 but it was a Fuel rich staged combustion engine. For the record: "In the staged combustion cycle, propellant flows through multiple combustion chambers, and is thus combusted in stages." Please correct me when I am wrong but it seems that the RL10 engine does not have a pre-burner, it is a Expander cycle engine. The mentioned "American engineers" probably thought about an oxidizer rich engine but they "deemed it impossible" so they came up with the SSME which is fuel rich, there is nothing wrong with that it is an achievement on its own. It could very well be that the article is incorrect but it is very hard to write something about an engine which was build but nobody knows about or was never build in the first place. Regards, --Felipe (talk) 09:57, 2 February 2018 (UTC)

SpaceX developing a staged combustion engine?
According to this, it seems that SpaceX is currently developing a fuel-rich methane/LOX staged-combustion engine. Quoting from the post:


 * Considering that:
 * When SpaceX President talked in the FH presentation, she stated that the Raptor Engine was a back burner project with something like just four people working on it.
 * Elon, when doing his AIAA presentation, mentioned a "super efficient staged combustion methane engine".
 * When Space X responded to an Air Force RFP, who where asking for a 300klbf to 500klb, 300s SL isp, reusable, RP-1/LOX engines, they specifically asked if they could submit a methane engine that they were working on "for other customer".
 * When he answered questions in the Reddit about the future fuels for space, he specifically talked about "light hydrocarbons, like methane".
 * So, all things here, point to a staged combustion, reusable, methane engine.

Was the F-1 rocket engine used on the Saturn V a staged combusion engine?
Was the F-1 rocket engine used on the Saturn V in the 1960s a staged-combusion engine? This source (New F-1B rocket engine upgrades Apollo-era design with 1.8M lbs of thrust) seems to say it was, but it doesn't use the term "staged". (The new engine design, circa 2013, the one they are calling the F-1B for now, is clearly NOT a staged-combustion engine, and explicitly uses the gas-generator cycle.)

If the F-1 is indeed staged-combustion, then we ought to add this notable rocket engine to the list in the Wikipedia article. Cheers. N2e (talk) 15:08, 15 April 2013 (UTC)


 * Simple answer: old & new F-1s are different, but they're both open cycle gas-generator engines. Andy Dingley (talk) 20:02, 15 April 2013 (UTC)
 * Longer answer: "gas generator" isn't a helpful label as both have a component that's of similar function: the precombustor in a staged-cycle. Sutton's labels of "open cycle" and "closed cycle" are rather more obvious. To quote, "Open denotes [...] discharged overboard, [...] in a nozzle of its own, or discharged into the engine nozzle at a point in the expanding section far downstream of the nozzle throat." vs. "Closed [...] all the working fluid from the turbine is injected into the engine combustion chamber"
 * In the original F-1, the turbine exhaust is hard to miss - the massive biifurcated pipe on the outside of the expansion nozzle that forms a horizontal tapered ring halfway down it. As above, discharging into the engine's own expansion nozzle, downstream of the throat. So it's open cycle (i.e. gas-generator). Andy Dingley (talk) 20:25, 15 April 2013 (UTC)


 * That's a very helpful answer, Andy. I was aware that the Dynetics design in 2013 is explicity different, and no question it is pure gas generator/open cycle by Sutton's definition.  But you've helped show that the F1-A is indeed "open cycle", at least.


 * Your comment brings up another question: Should we, in Wikipedia articles, perhaps be thinking about suing Sutton's open/closed cycles and definitions rather than "gas generator" and "staged combustion"?  Or should perhaps Sutton, 6th ed (if you have that text) be used to clarify the open/closed definitions from Sutton as an alternative classification scheme to the gas-gen/staged-combustion dichotomy in the existing articles?  Cheers.  N2e (talk) 04:20, 16 April 2013 (UTC)


 * The terms "gas generator" and "staged combustion" seem to be those that are most widely used. However they don't communicate simple understanding of the principle so well. I'm happy with either set of names (they are, AFAIK, exact synonyms) but I'd like to see a good explanation and comparison in the second para or so of both articles. I only have two editions of Sutton, 3rd and 6th, and I think that the "Apollo era" one in the middle might be interesting too. The examples used to illustrate theory (like Ricardo's High-Speed Internal Combustion Engine) change interestingly from edition to edition. Andy Dingley (talk) 15:13, 16 April 2013 (UTC)

Oxygen rich vs Fuel rich
The caption to the drawing indicates that "An oxygen rich circuit is possible also, but less common" Seeing as the majority of examples listed are Russian, which are Oxygen rich, should the caption be changed? 199.36.17.2 (talk) 15:37, 11 December 2014 (UTC)


 * The majority of the examples listed is not Russian(6:5 ratio)? Yes, the wording is a little unfortunate, but i think that currently the majority of rockets being launched use fuel-rich circuits. VietGwon (talk) 07:27, 12 December 2014 (UTC)

I had the same comment when reading this page. It is a fairly bizarre assertion to say that the majority of staged combustion engines are fuel rich, considering that only three fuel rich staged combustion engines have ever been developed (RS-25, RD-0120, and LE-7), whereas numerous (around 30 unique designs) engines have been developed using LOX/kerosene or NTO/UDMH with ox-rich powerheads. Furthermore this caption implies that metallurgy is the primary factor in determining whether a cycle is fuel-rich or oxidizer-rich. Rather, it is the thermodynamics of the propellants that determines the selection. Hydrogen engines are more powerful as fuel-rich cycles, while hydrocarbon engines are more powerful as ox-rich cycles. Note that the three fuel rich cycles that have been developed are all hydrogen engines, while all other staged combustion engines ever developed are either ox-rich or full flow cycles. Pkotrucking (talk) 05:29, 19 December 2014 (UTC)

Was CE-7.5 (and RD-56M) designed to be an ORSC engine? ORSC engine is designed to solve incomplete combustion in LOX/RP-1 engine and it is totally unnecessary for a LOX/LH2 engine since the performance will not be improved and gas generator and main injector will be very difficult to be manufactured.--Robin ceres (talk) 08:42, 6 August 2015 (UTC)

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Mistranslation
At the beginning of History it says "Staged combustion (Замкнутая схема) was first proposed..." but Замкнутая схема does not mean "staged combustion." It means "closed circuit," and combustion ain't there. Couldst fix please?

David Lloyd-Jones (talk) 14:40, 18 August 2016 (UTC)

Alternative name "closed cycle"
Question for someone with more rocketry knowledge than myself. "Staged combustion cycle" and "closed cycle" are synonymous, right? Can we add "closed cycle" to the lede sentence of this article? NickCT (talk) 14:23, 26 September 2016 (UTC)


 * Short answer? Not at all. The expander cycle can also be closed, and the Bristol Siddeley Gamma didn't had preburners. And then you have the Electric pump-fed engine, which technically, also uses all the propellant (but has the extra dry mass of the batteries). And then you have the piston-pumped engines from XCOR, which I guess could be a special case of the expander.


 * Long answer is that I'm thinking about how to approach the rocket combustion cycles. There are many variations, for example, there is a parallel to the full flow staged combustion on the expander case, called Dual Expander. I just added that to the article. But then you have the RD-0162 project by KBKhA, that uses expander on the fuel turbopump and oxidizer-rich stage combustion on the oxidizer turbopump.


 * Then I'm wondering if the steam generator rockets, like the V-2 rocket and RD-107, are a variation of the gas generator or their own cycle. The above mentioned gamma would be the staged combustion version of the steam generator cycle.


 * The Russians use a different method, where they worry how does the propellant reaches the injector. So the bleed expander, gas generator, steam generator, tap-off and electrically pumped are all liquid-liquid. The traditional expander and the staged combustion are liquid-gas. And the full flow, the dual expander and the expander plus ORSC are all gas-gas.


 * And the SSME, for example, use the expander to drive the low pressure pumps (which were used to avoid cavitation) and the rest was fuel rich stage combustion. The proposed methane version of the RD-170 was supposed to use the expander for that, too.


 * In the end there are a myriad of variations and may be what's needed is an article to make this point. Since I can't do original research in Wikipedia, I'm reviewing the bibliography to see if I can make something from existing sources without breaking any rules. But I will work on that. – Baldusi (talk) 16:45, 26 September 2016 (UTC)
 * - Ok thanks. I do wonder whether something like Rocket_engine could be spun out into it's own article. It would by nice to have an article that gave a rough explanation of the "myriad of variations". Right now, it's a little difficult to use WP to get a rudimentry definition for terms like "closed", "staged" and "expander". NickCT (talk) 13:11, 27 September 2016 (UTC)

Explain "a fuel that will not coke"
What does this refer to? coke? Diepes (talk) 19:03, 3 December 2016 (UTC)

Full-flow vs full
This is regarding this caption for the photograph:


 * Oxidizer-rich exhaust from a Spacex Raptor preburner shown during a sub-system test on a test stand at Stennis Space Center. In the full rocket engine, the preburner exhaust is fed into a turbine and then into the main combustion chamber.

An IP editor, Special:Contributions/23.162.0.162, replaced full rocket engine with full-flow rocket engine. I believe it makes more sense to emphasize the fact that the preburner shown in the image is just a system test. Then the second sentence explains the role of the pre-burner in the full engine. Of course, the engine is a full-flow staged combustion cycle engine - but since the photograph was already in the full-flow section of the article, I believe the intent of full rocket engine was to refer to the final, assembled engine. Therefore, I recommend that the caption retains full rocket engine. Appable (talk | contributions) 21:02, 20 July 2017 (UTC)
 * ✅ Toddst1 (talk) 23:37, 20 July 2017 (UTC)

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