J-2S vs RLX vs RS-68r+

GCNRevenger · 2006-01-26 23:14:25

No, a twin-SRB vehicle would be far too complex, require way more development, and have so much thrust the CEV would be too light and the high G-loads could kill the crew.

To clarify, the RS-68 would only be for the first stage of the big HLLV vehicle, a quartet replacing the quintet of SSMEs. A pair of J-2S engines would replace the single SSME on the upper stage of the CLV "TheStick" rocket, but the slightly lower performance would require the heavier five-segment SRB for it. The J-2S is already slated to power the EDS stage on the big HLLV, and may power the LSAM decent stage.

Austin Stanley · 2006-01-26 23:32:46

The SSME startup procedure, since it operates at such extremely high pressure and temperature, is very complex; many valves must be opened and closed in a particular sequence at exactly the right time for the engine to properly ignite. You would need to carry an additional Helium bottle for tank pressurization, and you would need some kind of small thruster to effect propellant settling. The big reason is though it was never intended to be fired in the icy vacuum of space nor more then once between careful inspection and refurbishing. Just look at the thing, does it look like its going to be easy to make a "cheap" version or modify it to ignite in the freezing vacuum after hours or days of the initial firing with minimal fuel "weight" versus sunny Florida at 1G? Even if it were reliable enough to fire repeatedly between overhauls, which its not.
The SSME as an upper stage makes great sense if your lower stage is under-powerd (CLV), or you have a really big payload (HLLV). There is just that niggling issue of getting it to air start and/or fire more then once per mission. Trouble is, this performance comes at too high a complexity.

I'm not sure what your point is here. Yes, the SSME is very complex, however on the other hand this complexity hasn't lead to any major trouble. It has proven to be reliable despite it's complexity. The shuttle already carries some Helium for valve opperation and tank pressurisation. I guess I just don't understand the diffrence bettwen air and vacume start. What makes it so difficult to re-start the engine in outerspace?

NASA needs the CEV, and it needs it now, and so whichever engine is used for the upper stage needs to be as closely based off the SSME or J-2S as is practical. Scaling up the J-2 isn't happening, it would be nice if you could squeeze a few more percent of thrust out of it, but no serious alterations to it are nessesarry or desireable. Perhaps NASA ought to focus on taking the current "luxury model" SSME and just make it work first, and then make a simplified model later.

This is one of the nice things about the current approach. It is very possible for us to design and launch a simple CEV now, and then later upgrade it with better engines later. Unlike the shuttle, which has virtualy no upgrade path. So maybe an RS-68 or an RL-10s now, and a simplified SSME later.

The SSME has fantastic Isp for a first stage, but only at altitude. During the first minute or two of acent, the air pressure is high compared to how much the propellant gasses expand, and so actually the RS-68 is dead even for Isp until getting up high. Then there are the gravitational losses to consider, and a quartet of RS-68s would have 16% more thrust then a quintet of SSMEs, and so using them instead should not cost as much payload as simple calculations indicate.

While this is true, it is less important in the situations we are talking about anyways. Both the shuttle and the HLV will have those huge solid rocket boosters to help eliminate gravitation losses, and get into the upper atmosphere more quickly. It still seems to me that the SSME is still ideal (aside from cost). In the Shuttle Derived heavy lift vehicle we will be building, it will be playing essentialy the same role it did in the orignial Shuttle, where it plays secound fiddle to the Boosters untill it gets to alltitude.

The only thing "wonderful" about the SSME is its high Isp at altitude and above-average reliability, thats it, thats all, period, end quote. In every other respect, its a terrible piece of equipment, and its especially a joke given its design purpose of reuseability. Due to its very high complexity, the thing cost triple at least what expendable engines (RS-68, RD-0120) do per-thrust.

Saying it is only excelent at reliablity, thrust, and ISP is kind of silly, because really these are three of the most important issues in rockets engines. And while it's cost may be high, it is a one time cost. The things can be re-used like 30 times each. Even with refurbishment costs, I have no doubt that re-using them will be cheaper on a per-thrust basis then any other engine.

Now lets not start this engine pod debate again, we've been over this before. Even with a self-righting ballistic reentry, you still:
-Need a heat shield at least 8m wide, and if it must be bigger then this, it will stick out the edges of the main tank.
-Need power, communications, tracking, and mission control for it
-Route fuel lines, structural connections, and wiring through the heat shield
-Airbags, parachutes, altimiters, airspeed indicator, accelerometers, etc
-Must resist impacts greater then designed for (soft Shuttle landing)
-Must not be damaged by plasma wake during reentry or hypersonic air

- Heat shield - a valid concurn. Sticking the 5 SSME underneath the HLV is a strech to begin with, and the engine pod does not improve things. I think the only solution to this is to either mount the thing off-axis (as in the shuttle) or redesign the main tank so they can fit. As the tank is going to have to be redesigned somewhat anyhow, I don't see how this is an issue.
- Routing things through the heat shield - The shuttle routs fuel-lines (and probably some control lines) through it's heat shield some how, so it can't be that big an issue.
- Airbags and control equipment - This stuff is already out there and can be picked up off the shelf without issue (like the parachutes). Some control systems and redudent sensors (esp accelerometers) are going to be needed on the first stage even if it is re-usable.
- Landing Impact - With a proper parachute size this shouldn't be that much greater than the shuttle's landing (which isn't realy all that soft). Besides, these things withstand take-off (3 G's or so) and re-entery and all the vibration hazards associated with both, so I don't think it's going to be that big an issue.
- Re-entery damage - The heat shield should be designed to keep them out of the wake obviously. The shuttle has to return through that same air, so this also should be doable.

Just as importantly though, if you lose the thing, you are in big trouble. How long does it take to build a new one? How much does that cost? If you have a time-sensitive launch (say, a Mars departure window) and your engine pod burns up then you can't put it on the next one. So how much does multiple backup pods cost? Or what if there is a snafu durring refurbishing/recovery?

There will have to be multiples, obviously. The pods aren't so large and complex that it should take all of the two-years or so bettwen launch windows to build another one.

Then there is the development... how much is THAT going to cost? Four RS-68s cost about $60-80M a flight, so unless recovery, refurbishing, and amoratizing construction costs anywhere close to this then I'm sure the development cost will wipe out any real cost advantage. Which you will have traded for having a proven, easy, fast arrangement that reduces the risk NASA will "run out of steam" politically before ever getting the HLLV off the ground if development drags on.

Boeing seems pretty confident that it can do just that, with total refurbishemnt costs for similar systems to what we are talking about comming in at under $60 Million. Rember the pod is going to bring back not just the engines, but any gimbles and associated equipment to. While I can see the need for a quick HLV development, an engine pod still seems to make sense as an later development.[/url]

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While I semi-agree that the US is probably going to avoid the RD-0120 for political reasons, it's not entirely impossible that a US company could license the design and produce a copy here. If the price was right, and they could be convinced of a need for it, I'm sure they could.

RobertDyck · 2006-01-26 23:43:19

Another possibility perhaps might be some kind of joint project to man rate on of those Russians engines.

The RD-0120 was developed as the main engines for the Buran space shuttle. It's already man-rated.

GCNRevenger · 2006-01-26 23:53:24

Another possibility perhaps might be some kind of joint project to man rate on of those Russians engines.
The RD-0120 was developed as the main engines for the Buran space shuttle. It's already man-rated.

To Russian standards. Energia was never flown enough to really prove the engine either.

RobertDyck · 2006-01-26 23:56:29

The issue with "air start" is ignition and propellant flow. Many stages rely on gravity to pull fuel down to the bottom of the tank, then acceleration to keep it down where the siphon is. Zero-G can cause fuel to drift away from the siphon so fuel pumps don't have anything to pump. Then there's the ignition system. SSME uses silane which ignites spontaneously in oxygen of air. That silane is sprayed sideways from the launch pad, it isn't on-board the Shuttle. But whatever you use for J-2 could be used for SSME. I don't see the problem. Are fuel pumps of J-2 robust enough to handle helium bubbles in LOX or LH2? Could SSME fuel pumps during start-up?

RobertDyck · 2006-01-26 23:59:01

Another possibility perhaps might be some kind of joint project to man rate on of those Russians engines.
The RD-0120 was developed as the main engines for the Buran space shuttle. It's already man-rated.
To Russian standards. Energia was never flown enough to really prove the engine either.

Tested more extensively with ground tests than any other rocket in history. And launched twice successfully; once with Buran, once with Polyus, 4 RD-0120 engines each time. How many times was Shuttle launched before it flew with humans onboard? (answer: none)

GCNRevenger · 2006-01-27 00:27:13

The very high complexity of the SSME's design and operation means that any changes to either will entail a pretty involved development. Just changing the ambient air pressure the engine will fire at requires a change in the intricate dance of valve sequences I'm sure. SSME isn't going to be ignited in a vacuum either, it will still be in the atmosphere when it seperates from the SRB on TheStick, but it will be pretty high up.

NASA has already abandoned the idea of restarting the SSME, thats not happening. Just igniting the thing more then once presents a big increase in risk, but mainly since it was never designed for it.

"This is one of the nice things about the current approach. It is very possible for us to design and launch a simple CEV now, and then later upgrade it with better engines later. Unlike the shuttle, which has virtualy no upgrade path. So maybe an RS-68 or an RL-10s now, and a simplified SSME later."

No. NASA doesn't have the time or the money to monkey with the CEV design much, whatever design they settle on would cost too much to change to a different engine. RS-68 lacks Isp and RL-10 lacks thrust, which leaves only J-2 and SSME for American-built upper stage engines. It might be possible to start with the "regular" SSME and switch to a simplified version later was what I was getting at. Switching from SSME to J-2 or back isn't happening.

"Both the shuttle and the HLV will have those huge solid rocket boosters to help eliminate gravitation losses, and get into the upper atmosphere more quickly. It still seems to me that the SSME is still ideal (aside from cost)"

True, but more thrust the merrier during the first moments of launch, and the RS-68s will still put out 15% more than SSME. Overall, we're talking ~5-10MT payload penalty for a $140M savings in engine cost per-flight, which is a good deal I think.

"Saying it is only excelent at reliablity, thrust, and ISP is kind of silly"

I didn't say its thrust was excelent, since its not powerful enough for the big HLLV except in a quintet, which directly impacts the total vehicle reliability and cost. Good Isp and good reliability for poorer thrust and much higher cost.

"I think the only solution to this is to either mount the thing off-axis (as in the shuttle) or redesign the main tank so they can fit. As the tank is going to have to be redesigned somewhat anyhow, I don't see how this is an issue. "

Not happening:
-Side mount substantially reduces efficiency due to thrust wasted laterally and drag, reducing payload too much.
-Changing tank diameter would involve too radical a change from STS-ET tooling, wider launch table mounts/flame trench, and change tank structure/capacity relative to other componets.

And where are we going to get a heat shield >9m wide? I think it would be alot of trouble to build one cheaply, reliably, and most of all light weight so that it doesn't impact payload much.

"Routing things through the heat shield - The shuttle routs fuel-lines (and probably some control lines) through it's heat shield some how, so it can't be that big an issue. "

Yes it is. The Shuttle connect points are on the bottom of the shield, and Shuttle does not reenter ballisticly. A regular ablative ballistic heat shield with penitrations would be very hard to build doors in due to the heating and burning off of material I would think. Remember how parinoid NASA was about capsule heat shields? These penitrations must also accomodate much more fuel and load then Shuttle, so they will be by no means small.

"Landing Impact - With a proper parachute size this shouldn't be that much greater than the shuttle's landing (which isn't realy all that soft). Besides, these things withstand take-off (3 G's or so)"

The G-loadings that the SSME engines experience are relativly gradual, not sudden like a sharp impact, which makes a big difference. Just like in a car wreck, its not the speed that gets you, its the stopping. The SSMEs are very delicate pieces of hardware, and I would be worried about dropping them like this and reusing them repeatedly.

"The pods aren't so large and complex that it should take all of the two-years or so bettwen launch windows to build another one."

Why not? You are talking about a vehicle on the same order of complexity as the CEV capsule, except bigger and heavier. It might take quite some time to build a replacement unit.

"Boeing seems pretty confident that it can do just that, with total refurbishemnt costs for similar systems to what we are talking about comming in at under $60 Million. Rember the pod is going to bring back not just the engines, but any gimbles and associated equipment to. While I can see the need for a quick HLV development, an engine pod still seems to make sense as an later development."

I think Boeing's plan is pretty audacious really. Plus, these engines will still be handled by the Shuttle guys, which is going to lead to a hefty markup. Modern gimbles and computers are pretty simple on modern engines like RS-68 compared to thirty year old ones like SSME.

Also, since this is going to be a fully autonimous space capsule designed to return a pretty heavy precious cargo intact, its going to cost like one too, and I think the development will be pretty hefty. Since development costs are such a boogeyman, I think its a valid question if you will save enough money on each flight versus expendable engines when you factor in development and the older and higher tollerance man rated nature of the engine.

The full-on Shuttle grade SSMEs are going to cost like $200M a flight for the big SDV versus $60-80M for RS-68. If it costs Boeing, in the region of $50M, correcting for back in whenever-it-was dollars in the imaginary salement price land, to turn the pod around then I really don't see the bennefit. $30M a flight versus like $1-2Bn in development doesn't make much sense to me, given the delays and risks involved.

GCNRevenger · 2006-01-27 00:29:03

Hmmmm I didn't know that about RD-0120's ground test, although I would still want more launches before putting people on top of multiple of them.

That would also be because NASA has been playing fast and loose with Shuttle since the beginning, hard to blame them though, they had to produce or else.

I would be worried the Silane wouldn't hang around long enough to ignite in a supersonic air stream, which is a concern for air start too. J-2 uses a very small solid rocket/gas generator built into the engine to provide high pressure gas to start the thing up, and simply carries multiple of them to start more then once. It would be very hard to build this into SSME with its complex turbine arrangement and not being designed for this ignition method. The J-2's ignition is made possible by its simple design I bet.

SpaceNut · 2006-01-28 22:19:14

All this talk about engines of the past as well as SLI and other programs got me thinking about the OSP. The programs were all active just before all things were tipped on there heads with the vision redirection.

First Boeing Delta 1V Heavy Candidate to Launch the OSP Is Assembled for Tests This was an article dated September 6, 2003.

The nearly 2-million-lb.-thrust vehicle combines three Delta IV common booster cores and three Rocketdyne liquid oxygen/hydrogen RS-68 engines.
The IV Heavy, and its enlarged upper stage, powered by an advanced version of the Pratt & Whitney RL10 oxygen/hydrogen engine, is designed to place more than 50,000 lb. in low-Earth orbit and nearly 30,000 lb. into geosynchronous-transfer orbit.
THE VEHICLE WILL liftoff on about 2-million-lb. thrust with all three RS-68s at 102% power. All three will remain at that level until 50 sec. into the flight when the core engine will throttle down to 57% power, or 425,500 lb. thrust. The two outboard engines will remain at 102% at this time, each generating about 650,000 lb. thrust at altitude.
The profile will be tailored so the Heavy with its 5-meter (16.5-ft.)-dia. shroud--on later flights stretching up to 73 ft. in length--will actually experience a lower dynamic pressure than Medium versions of the Delta IV with four solid rocket motors.

Lots of these details look more than I think just by chance the same...

GCNRevenger · 2006-01-29 15:32:16

The big Delta-IV is about powerful enough, but I don't think that NASA would consider it for CEV unless in a dire situation.

John Creighton · 2006-01-29 18:17:53

The big Delta-IV is about powerful enough, but I don't think that NASA would consider it for CEV unless in a dire situation.

The biggest reason for that would be safety right? As we all know the solid rocket boosters are by far the safest rockets ever built.

PurduesUSAFguy · 2006-01-29 18:31:56

The big Delta-IV is about powerful enough, but I don't think that NASA would consider it for CEV unless in a dire situation.
The biggest reason for that would be safety right? As we all know the solid rocket boosters are by far the safest rockets ever built.

I don't think there is any chance of NASA going with the Delta IV heavy for the Crew launcher, there are too many failure modes in the triple barrel configuration and I think the stick has more potential for being lower cost, the RSRB has been in production for many years and has been reliably produced at cost, unless boeing was willing to sell CBCs on a true comercial basis for less then an RSRB.

GCNRevenger · 2006-01-29 19:14:54

There are a number of reasons the big Delta-IV Heavy doesn't make sense as a crew launcher... the first and foremost is that its not very responsive, that it takes a long time to put one together (especially if its done on pins-and-needles to maximize crew safety versus satelites) and it would be hard to hold a tight launch window (the last D-IV-H sufferd alot of delays).

Second up, or maybe first, its not safe enough. It was designed to carry satelites and not humans, and it would require some modification to make it extra safe I bet, which wouldn't come cheap. The fact that the thing carries sooo much more Hydrogen would make a pad abort extra scarry, since you might be coming back down into that inferno. A solid doesn't blow up.

Then there is the track reccord...
RSRB: almost 200 flights
D-IV-H: one flight

And lastly, maaaybe, cost... NASA might be able to build and fly TheStick for less then the big Delta, if they can keep labor and engine costs on a short leesh.

SpaceNut · 2006-01-31 21:37:23

NASA Tests New Breed of Propulsion Engine and System in Support of the Vision for Space Exploration

NASA engineers have successfully tested a new breed of reaction control engine and propulsion system. Aimed at furthering NASA's space exploration goals, the tests helped investigate the possibility of future space travel fueled by non-toxic propellants.

So where does this engine fit on the CEV and why is it needed since I am not knowledgeable of the term.....

PurduesUSAFguy · 2006-01-31 22:15:01

NASA Tests New Breed of Propulsion Engine and System in Support of the Vision for Space Exploration
NASA engineers have successfully tested a new breed of reaction control engine and propulsion system. Aimed at furthering NASA's space exploration goals, the tests helped investigate the possibility of future space travel fueled by non-toxic propellants.
So where does this engine fit on the CEV and why is it needed since I am not knowledgeable of the term.....

The main goal is to try and minimize, or simply get ride of Nitrogen Textroxide and Hydrazine(and it's derivatives) out of the space program. They are both toxic, and unstable and produce toxic exhaust. The nice thing about them though is that they are storable and ignite on contact with each other.

RobertDyck · 2006-02-02 08:19:06

SSME:
thrust 232,301 kgf
engine mass 3,177 kg
Isp (vacuum) 453 seconds, Isp (sea level) 363 seconds
burn time 480 seconds
life: 7.5 hours, 55 starts
on-board spark igniter
throttle to 65% (minimum power is higher at sea level to prevent flow separation)

RD-0120:
thrust 200,000 kgf
engine mass 3,450 kg
Isp (vacuum) 455 seconds, Isp (sea level) 359 seconds
burn time 600 seconds
throttle to 45%

RD-0120M:
thrust 200,000 kgf
engine mass 3,450 kg
Isp (vacuum) 455 seconds, Isp (sea level) 372 seconds
burn time 600 seconds
throttle to 28%
Encyclopedia Astronautica reference: RD-0120M

RD-0120M was developed for the core stage of Energia-M (smaller Energia) but currently planned for use on Angara stage 2. Air startable, in production.

Again I have to point out, so much equipment is necessary to return to the Moon, why waste time and money developing something that's COTS? (Commercial Off The Shelf) Instead work on new stuff. Get it done, go now.

PurduesUSAFguy · 2006-02-02 08:42:56

I think it should be pointed out that list cost in Russia and the cost they are willing to sell on the market at, especially to the US governemtn are two completely unrelated things? Has anyone seen the actually cost accounting on what a Soyuz launch runs? Here's a hint, the alleged $20million that the tourist have paid would have paid for the entire launch plus a healthy profit.

Also, I have serious doubts about the Russians ability to ramp up production with anything like the quality control and reliability of a US supplier.

Also we can't forget, this isn't the ISS, we aren't going international (thank god). There would be serious political backlash if we outsourced engine development. Not to mention the fact that the US aerospace industry is suffering from such a shortage of aerospace engineers that the INS recently approved a fast track program for Boeing to hire and import out of work Russian engineers.

RobertDyck · 2006-02-02 09:11:14

Also, I have serious doubts about the Russians ability to ramp up production with anything like the quality control and reliability of a US supplier.

Now that I have to take exception with. That's just bullshit. You can make all sorts of political complaints about the government of the former Soviet Union, but Russian aerospace has always been a strong rival to the US.

Canada is part of NORAD and my city is on direct line of flight from Russia to ICBM silos in North Dakota. In the 1970s one Canadian soldier told me that if Russian ICBMs were confirmed incoming, we would have 15 minutes to evacuate the city; and she expected 3 Russian warheads tagetting Winnipeg: airport/air force base, main railway yard, downtown. There's no way we could evacuate a city of ~650,000 people in 15 minutes. Personally, I'm very glad the cold war is over.

Russian fighter planes have always been leading edge and a rival for the best American planes. The R-7 rocket was the first ICBM, and the Soyuz launch vehicle is an evolved R-7. When America chose to stop developing liquid fuel rocket engines in favour of solids, Russia continued development of liquid fuel rockets. What's the success ratio of Shuttle compared to Soyuz?

We've already seen the decision to abandon LOX/methane in favour of old fashioned hypergolics. What else will be abandoned? This is NASA's pattern since Shuttle: start developing something new, complain it's too hard, abandon it and return to pre-Shuttle technology. The new architecture is "Apollo on steroids", but every tiny piece that isn't pre-existing technology is at risk of cancellation. Modifying SSME isn't hard, but if there's already complaints that it's too hard and excuses to return to J-2 (not even J-2S but the old J-2), then we have a serious problem. All of VSE is in danger. There's no need to develop a simplified SSME at all, RD-0120M is COTS. It's time to cut off excuses and just do it.

PurduesUSAFguy · 2006-02-02 09:24:54

Also, I have serious doubts about the Russians ability to ramp up production with anything like the quality control and reliability of a US supplier.
Now that I have to take exception with. That's just bullshit. You can make all sorts of political complaints about the government of the former Soviet Union, but Russian aerospace has always been a strong rival to the US.
Canada is part of NORAD and my city is on direct line of flight from Russia to ICBM silos in North Dakota. In the 1970s one Canadian soldier told me that if Russian ICBMs were confirmed incoming, we would have 15 minutes to evacuate the city; and she expected 3 Russian warheads tagetting Winnipeg: airport/air force base, main railway yard, downtown. There's no way we could evacuate a city of ~650,000 people in 15 minutes. Personally, I'm very glad the cold war is over.
Russian fighter planes have always been leading edge and a rival for the best American planes. The R-7 rocket was the first ICBM, and the Soyuz launch vehicle is an evolved R-7. When America chose to stop developing liquid fuel rocket engines in favour of solids, Russia continued development of liquid fuel rockets. What's the success ratio of Shuttle compared to Soyuz?
We've already seen the decision to abandon LOX/methane in favour of old fashioned hypergolics. What else will be abandoned? This is NASA's pattern since Shuttle: start developing something new, complain it's too hard, abandon it and return to pre-Shuttle technology. The new architecture is "Apollo on steroids", but every tiny piece that isn't pre-existing technology is at risk of cancellation. Modifying SSME isn't hard, but if there's already complaints that it's too hard and excuses to return to J-2 (not even J-2S but the old J-2), then we have a serious problem. All of VSE is in danger. There's no need to develop a simplified SSME at all, RD-0120M is COTS. It's time to cut off excuses and just do it.

I'm not doubting the prowess of the Russian aerospace industry, quite the opposite infact they impress me with what they manage to pull off, especially with what is essentially no computer modeling. Also it is a fact, that Russians prefeer to engineer to looser tollerances, good, bad, or ugly, it's just the way it is. My reliaibility comment was not meant about the reliability of the engine, I'm sure it would likely work fine, but I just don't think we trust them as a supplier, there are political unrest issues, there are workforce issues, oh, and by the way the Russians are a long time supporter of Iran so if they do anything off the reservation guess where there might be trade sanctions against just like there were recently against Austria? Also, we are arguing about an engine that isn't even in production. Maybe I'm just a jigonist, but I'll take American vaporware over Russian vaporware any day of the week.

As far as Canada being apart of NORAD (Now called NorthCom actually)and maybe RVs falling on Canadian soil if the greatest show on Earth would have kicked off. Yes, Canada has always been a great friend. I actually used to live in Canada, (Kingston, Ontario to be specific) and my family still has a summer home up there in the Thousand Islands. I'm not sure how the point is salient though...

RobertDyck · 2006-02-02 09:38:51

As far as Canada ... I'm not sure how the point is salient though...

I'm saying I'm not a pink-o commie Russian lover. I believe in democracy and freedom, international cooperation and trade. If a Russian engine is available now and it's so hard to develop a domestic one, use the Russian one.

Enclyclopedia Astronautica lists RD-0120 as "Out of Production", but RD-0120M as "Hardware".

::Edit:: Yes, Russian rockets do have a healthy profit margin. If you want them to be a free market economy, why is that a problem? If they can sell superior quality equipment at a lower price, why is the profit margin an issue? If American aerospace manufacturers were any good, they would use the profit margin to drastically undercut the Russian price. But they either can't or won't. Based on published costs in year 2000 for Mir, Russian equipment has about a 10 times mark-up (90% profit margin). If American companies can't compete with that, it tells you how over-priced major American aerospace companies are.

GCNRevenger · 2006-02-02 10:08:46

"RD-0120M (is) in production"

To quote a phrase, "bullshit:" no version of the RS-0120 is in production anywhere, nor has been for many years. The Angara is still being developed, isn't anywhere close to flight yet, and it will start life with a regular "light" upper stage with the RD-0120 version as a (distant) future upgrade.

I agree with USAFguy, that Russia is capable of building perfectly good engines, but I don't think they are a sufficently reliable supplier. They haven't built these engines in a long, long time and NASA can't afford for them to hold up the CEV.

"What's the success ratio of Shuttle compared to Soyuz?"

Russia-worshiping stupid bullshit: oh please Robert, you aren't seirously comparing the two radically different vehicles are you? Thats just dumb, I wouldn't expect something like that from you.

"this isn't the ISS, we aren't going international"

I think when Mike Griffin was quoted saying the ISS was a mistake, that he meant it. The VSE program is going to be American, and buying major componets from a country that would love to have a new tool to exert political pressure against us is just not happening. Its not going to happen, the political cost for RD-0120 is simply astronomical, which makes its financial cost or performance irrelivent. Again, if NASA runs out of political capital, it will be dead just as surely as if it ran out of financial capital.

"We've already seen the decision to abandon LOX/methane in favour of old fashioned hypergolics. What else will be abandoned? This is NASA's pattern since Shuttle: start developing something new, complain it's too hard, abandon it and return to pre-Shuttle technology. The new architecture is "Apollo on steroids", but every tiny piece that isn't pre-existing technology is at risk of cancellation."

I don't think that you fully appreciate the gravity of NASA's situation, Robert: if NASA can't make VSE work, NASA will die. If NASA can't get VSE started such that canceling VSE would be politically impractical for future administrations, NASA will very likly then die too. This is a life or death situation, either NASA suceeds SOON or NASA could well cease to exsist.

NASA also balences on the edge of a knife financially as well as politically, that since the Shuttle and the ISS continue to suck up so much money, and we will be bound to keep spending on the ISS after Shuttle, NASA's budget is cut to the bone. It has just enough money, in theory, to make it happen and so cost overruns are much more important then they used to be.

So NASA dropped the Methane engine in favor of regular hypergolics; why? Because developing a brand new engine would take time and money, two things that NASA is in short supply especially now. Very especially now. Its taken a pretty long time to develop the RL-60, which will be of the same class as the Methane engine, so NASA rightly decided to skip it.

The Methane engine wouldn't substantially improve performance, and Hydrogen would be preferred when we have a Moon base, and so it is a simple and smart matter to trade a little technology we won't need for twenty years to reduce the risk and cost of CEV and the Moon now. Right now, the quesiton needs to be asked and re-asked, what do we NEED for the Moon? Mars tech is important, but Moon tech is life-or-death.

"Modifying SSME isn't hard"

Says you. I don't think you know what you are talking about... even if its just to take the stock Shuttle engine and make it air-startable, forgetting all the simplification stuff, would still be pretty difficult. Then you are putting the CEV in the hands of the SSME builders: I'm not sure these guys are up to the task with such a complex engine, and so dropping the engine is the right choice to reduce CEV risk. Furthermore, if the SSME is the biggest thing (possibly) holding up the CEV, the trade between accelerating 5-segment RSRB and J-2S+ makes sense given that the J-2 option is technically easier. Saves money having to develop one less engine too. Even the regular J-2 would be easier the cheaper and possibly faster then SSME.

"As far as Canada being apart of NORAD"

Um, the Canadian thing really has no bearing on this discussion I don't think... and that flipping idiot Paul Martin rejected involvement in the ICBM defense system too.[/i]
____________________________________________________________________

Edit: This really struck me...

"But they either can't (US companies build rockets as cheap as Russias)"

More really obtuse bullshit... its because American engineers are paid ten times what Russian ones are! There is no possible way American engineers can compete with Russian ones, because they work for less money then you'd get paid flipping burgers over here.

GCNRevenger · 2006-02-02 11:55:32

RS-68:
thrust 337,807 kg
Isp (vac) 420 sec
Isp (sea level): 365 sec
Mass Engine: 6,597 kg

"The RS-68 utilizes a simplified design philosophy resulting in a drastic reduction in parts compared to current cryogenic engines. This design approach results in lower development and production costs."

...to less then half the cost of SSME per copy

J-2S:
thrust 116,100 kg
Isp (vac) 426sec
Mass engine: 1400kg

"The J-2S program consisted of six flight configuration engines tested at both sea level and vacuum conditions in 273 tests for a total operational experience of 30,858 seconds. At the completion of the program the engine was fully developed and ready to go into certification for flight operations."

...And is way, way simpler then SSME. Several copies are in storage, most recently used in clusters for the X-33 engine. The regular classic J-2 engine has similar performance, but even this more complicated engine is far and away simpler to build then SSME. It wouldn't require any modification either beyond making it compatible with modern control systems.

cIclops · 2006-02-03 02:29:38

Given the light weight of the J-2S, is it possible to bundle several of them together to produce the same or more thrust than the RS-68?

GCNRevenger · 2006-02-03 06:55:18

Possible? Yes. Practical? I doubt it.

publiusr · 2006-02-03 14:11:43

RS-68 and J-2 are two great engines that would go well together. With the ablatives, you don't even need channel-wall--

--though that shouldn't be too hard to copy if need be.

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#26 2006-01-26 23:14:25

Re: J-2S vs RLX vs RS-68r+

#27 2006-01-26 23:32:46

Re: J-2S vs RLX vs RS-68r+

#28 2006-01-26 23:43:19

Re: J-2S vs RLX vs RS-68r+

#29 2006-01-26 23:53:24

Re: J-2S vs RLX vs RS-68r+

#30 2006-01-26 23:56:29

Re: J-2S vs RLX vs RS-68r+

#31 2006-01-26 23:59:01

Re: J-2S vs RLX vs RS-68r+

#32 2006-01-27 00:27:13

Re: J-2S vs RLX vs RS-68r+

#33 2006-01-27 00:29:03

Re: J-2S vs RLX vs RS-68r+

#34 2006-01-28 22:19:14

Re: J-2S vs RLX vs RS-68r+

#35 2006-01-29 15:32:16

Re: J-2S vs RLX vs RS-68r+

#36 2006-01-29 18:17:53

Re: J-2S vs RLX vs RS-68r+

#37 2006-01-29 18:31:56

Re: J-2S vs RLX vs RS-68r+

#38 2006-01-29 19:14:54

Re: J-2S vs RLX vs RS-68r+

#39 2006-01-31 21:37:23

Re: J-2S vs RLX vs RS-68r+

#40 2006-01-31 22:15:01

Re: J-2S vs RLX vs RS-68r+

#41 2006-02-02 08:19:06

Re: J-2S vs RLX vs RS-68r+

#42 2006-02-02 08:42:56

Re: J-2S vs RLX vs RS-68r+

#43 2006-02-02 09:11:14

Re: J-2S vs RLX vs RS-68r+

#44 2006-02-02 09:24:54

Re: J-2S vs RLX vs RS-68r+

#45 2006-02-02 09:38:51

Re: J-2S vs RLX vs RS-68r+

#46 2006-02-02 10:08:46

Re: J-2S vs RLX vs RS-68r+

#47 2006-02-02 11:55:32

Re: J-2S vs RLX vs RS-68r+

#48 2006-02-03 02:29:38

Re: J-2S vs RLX vs RS-68r+

#49 2006-02-03 06:55:18

Re: J-2S vs RLX vs RS-68r+

#50 2006-02-03 14:11:43

Re: J-2S vs RLX vs RS-68r+

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