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#1 2007-04-14 03:26:28

gaetanomarano
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Re: Ares-F : The French Ares-I

.

as posted by Mars_B4_Moon in the Orion's thread, the Lockheed-Martin Corp. CEO Robert Stevens said in an interview that he have fear the U.S. is in danger of "ceding our spaceflight leadership to Russia, China and even India": http://www.eetimes.com/news/latest/show … =198900572

so, why don't build the new hardware FASTER ?

my latest suggestion is to use the ready available Vulcain 2 engine for the Ares-I 2nd stage and the Ares-V EDS to save several hundreds million$ and 4+ years of R&D time

the Vulcain 2 already has the required vacuum thrust (303,490 lbs.) that a J-2x just "hope to have" at the end of its (very long) R&D trip (295,000 lbs.)

a further suggestion is to build an "Ares-F" with the Ariane5-derived hardware: http://www.gaetanomarano.it/articles/024aresF.html

following this way, the first manned Orion flight will happen in 2012 as planned in the early (non delayed) ESAS timeline

.


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#2 2007-04-15 21:17:11

GCNRevenger
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Re: Ares-F : The French Ares-I

It would cost several hundreds of millions of dollars just to man-rate the engine, license the technology, and figure out how to build the thing anyway. Vulcain engines don't have anywhere near the proven reliability of J-2 either.


[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

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#3 2007-04-16 04:46:55

gaetanomarano
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Re: Ares-F : The French Ares-I

It would cost several hundreds of millions of dollars just to man-rate the engine, license the technology, and figure out how to build the thing anyway. Vulcain engines don't have anywhere near the proven reliability of J-2 either.

that's true, infact I've not said it costs "zero" but "less" since it already exists, while the J-2x must be (first) developed and built (then, man-rated) also, the reliability of the new J-2x can't be "sure" from scratch, but must be verified with real (new) tests


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#4 2007-04-16 07:31:05

GCNRevenger
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Re: Ares-F : The French Ares-I

No it won't cost any less, because much of the J-2 engine already exists. Considering the not-so-good track record that Vulcain has had, it would be just as hard and take just as long and cost just as much to develop a version of it safe enough to put people on.

And you don't seem to know much about how engineers make things reliable, the reliability of the engine is the sum of all the individual reliabilities of its components plus the interaction between them. We already know much of the J-2 engine is reliable, we're going to build new nozzles for it like the reliable SSME/RD-0120. It is also a pretty simple engine for its size compared to Vulcain or SSME, which makes unforeseen interactions unlikely. We know it will be reliable.


[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

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#5 2007-04-16 07:43:33

gaetanomarano
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Re: Ares-F : The French Ares-I

No it won't cost any less...

the J-2x need 6+ years to fly (IT'S OFFICIAL) while the Vulcain 2 is ready available NOW and only needs to be man-rated
use a ready available engine already IS a giant money saving, but the greatest saving is TIME
thanks to the J-2x R&D (very long) timeline, the first Orion launch will be 3+ years LATER
and, since "time IS money" (especially for a big space agency like NASA) three years less than planned may allow NASA to save SEVERAL BILLION$$$ on fixed agency's costs (costs that NASA must pay ALSO in the 3+ years when NOTHING will fly)


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#6 2007-04-16 11:06:27

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Re: Ares-F : The French Ares-I

Its so "öffical" that you don't provide any links

Vulcain man rating, considering how it is not such a reliable engine, would take several years at least too. We already have about half the J-2 engine also, with a good idea how to build the other half (borrow technology from RS-68/SSME Block-III). It would also take time to arrange a licence from France to use their engine even if we were buying them from the French, which would likely take a year or so. Several years if we were going to build our own copies.

So it doesn't really save much time. Four years versus five or six? And your assertion that "Orion will be delayed 3+ years because of J-2!!!!" is nonsense. It will take quite a bit of time to perfect the rest of the rocket and the capsule while J-2X is being finished.


[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

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#7 2007-04-16 16:36:54

GCNRevenger
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Re: Ares-F : The French Ares-I

Hey wait a minute...

Vulcain is a first stage engine, not an upper stage engine!

Which means it must be heavily modified for air-start, restartable, and lower ambient pressure than the ground-start version you call for. J-2 already has all these things.

This was the biggest reason SSME was rejected, since the modifications would be too complex and costly.


[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

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#8 2007-04-17 10:35:12

gaetanomarano
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Re: Ares-F : The French Ares-I

Its so "öffical" that you don't provide any links

this is the SpaceNut's (Aug. 06, 2006) post reporting an Huntsville Times' interview to the MSFC officials about the J-2x:

http://www.newmars.com/forums/viewtopic … 0916#90916

and this is YOUR angry comment:

http://www.newmars.com/forums/viewtopic … 0917#90917

and, since the news is from August 2006, you must add a further year of delay (of the full ESAS plan, not the J-2x alone) due to the Congress' cuts of NASA funds a few weeks ago (that shifted the first planned Orion launch from 2014 to 2015)

total: 7 years (+ future, unknown, delays)

Vulcain man rating...

also the J-2x must be man-rated, so, its cost is similar

even if we were buying them from the French...

I'm sure that, if NASA will buy the Vulcain 2, the France will send them as fast as possible... smile

also, since it's a prestige for France to drive the Ares-I with the Vulcain 2, it's possible that France will give three dozens of engines FREE (or may exchange the $500M engines' value with a free seat for a french astronaut in one of the Orion's missions)

.


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#9 2007-04-17 10:42:15

gaetanomarano
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Re: Ares-F : The French Ares-I

...the biggest reason SSME was rejected, since the modifications would be too complex and costly...

no, the main reason the SSME was deleted is that it ALREADY is too expensive: $60M per unit compared with $20M each for the RS-68 and $12M each for the J-2x ...two other reason the SSME was deleted are the choice of the RS-68 for the AresV and the (simple) fact that the SSME is out of production... surely, air-start the Vulcain 2 needs time, but I doubt it may even need 7+ years to fly like the ('60s' design) J-2x !!!
.


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#10 2007-04-18 05:31:09

cIclops
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Re: Ares-F : The French Ares-I

So we are all agreed that the SSME is too expensive smile

What does a Vulcain 2 engine cost?


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#11 2007-04-18 06:23:19

gaetanomarano
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Re: Ares-F : The French Ares-I

So we are all agreed that the SSME is too expensive

not exactly, because... 1) the SSME unit price is higher than RS-68 but it is a fraction of the costs of the full ESAS plan (so, use the SSME doesn't change so much) ... 2) the SSME is available NOW (and already man-rated) while the J-2x will be available within 7+ years, and... 3) the number of the "already paid" SSMEs is around 15 (nine on the Shuttles and six new stored as spare parts) that's a value near $1Bn, so, if NASA will use the SSME, in the first 15 (test and operational) flights, the engine will costs $0.oo ...so, NASA can use the 15 "free" SSME for all Ares-I tests and all ISS (10-12) ISS flights in 2015-2020, then, they have 15 years of time (not seven) to develop the J-2x and the RS-68 for the lunar Ares-I and Ares-V using the (much more RICHER) FY 2011-2019 budgets (thanks to the Shuttle retirement in 2010)

What does a Vulcain 2 engine cost?

I don't know the exact price of a Vulcain 2... times ago I've read of prices around $15M ...however, the price of the engine is only PART of the problem since you must consider that: 1) a simpler Ares-I costs LESS billion$$$ for R&D... 2) the France may give FREE three dozens of Vulcain 2 to NASA (for prestige) and/or exchange the engines with a seat for a french astronauts in a lunar mission... 3) the NASA fixed costs per year of the manned flights' division is around 60% of the entire budget (IIRC) no matter if NASA launches one, ten or zero Shuttles or Orion! ...so, 3+ years of delay of the first Orion flight (2015 insetad of 2012) may cost 20+ billion$$$ of fixed costs to NASA ...a GIANT waste of money ...for nothing!!!
.


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#12 2007-04-18 06:44:09

cIclops
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Re: Ares-F : The French Ares-I

not exactly, because... 1) the SSME unit price is higher than RS-68 but it is a fraction of the costs of the full ESAS plan (so, use the SSME doesn't change so much) ... 2) the SSME is available NOW (and already man-rated) while the J-2x will be available within 7+ years,

Ok let's disagree.

1) comparing the cost of upgrading the SSME with the full ESAS plan to develop Ares I/Ares V/Orion/LSAM is absurd

2) SSME is not available now for the Ares I US, it can't air start and the program to upgrade it would take years. J-2X will be available for the Orion 3 test flight in Oct 2011 according to the latest official NASA chart - that's in about 4.5 years.


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#13 2007-04-18 07:17:09

gaetanomarano
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Re: Ares-F : The French Ares-I

...comparing the cost of upgrading the SSME with the full ESAS plan to develop Ares I/Ares V/Orion/LSAM is absurd...

no, just said there is no problems of funds if they want to use the SSME

...is not available now for the Ares I...

as said for the Vulcain 2, air-start an existing (and already man-rated!) SSME (surely) needs time and money, but not so much time and money like (first) develop and build it

...that's in about 4.5 years...

4.5 years still are too much for the NASA budget, also, the 2011 test will be UNMANNED and without the Orion (ready in 2012) so you must add the man-rating time, the tests with a dumb Orion, the orbital tests and (finally) the first manned launch in 2015 ...that can't happen if they use an engine ready available NOW
.


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#14 2007-04-18 08:00:22

cIclops
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Re: Ares-F : The French Ares-I

as said for the Vulcain 2, air-start an existing (and already man-rated!) SSME (surely) needs time and money, but not so much time and money like (first) develop and build it

The cost of upgrading Vulcain is probably more than developing J-2X as J-2X is an upgrade of an existing man rated, air startable engine and Vulcain is neither.

4.5 years still are too much for the NASA budget, also, the 2011 test will be UNMANNED and without the Orion (ready in 2012) so you must add the man-rating time, the tests with a dumb Orion, the orbital tests and (finally) the first manned launch in 2015 ...that can't happen if they use an engine ready available NOW.

Right now 4.5 years is not a problem for Ares I as the budget is not available for faster development. As you say currently the first flight with crew is Mar 2015, that is 8 years from now sad Man rating design and development must be finished before the first test flight. The test flights prove the integrated  system.


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#15 2007-04-18 08:50:04

gaetanomarano
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Re: Ares-F : The French Ares-I

The cost of upgrading Vulcain is probably more than developing J-2X as J-2X is an upgrade of an existing man rated, air startable engine and Vulcain is neither

just imagine that "man-rate" a rocket needs the same time (e.g. two years) to learn how to fly with a new airplane...
if you have the airplane NOW, you'll fly in 2009, while, if you have the airplane in 2010, you'll fly in 2012
also, don't forget that, between 2012 and 2015, great part of the NASA manned-flights' fixed budget (infrastructures, emplyees, etc.) will be spent for NOTHING, so, this 3+ years delay (mainly due to the J-2x) will cost SEVERAL BILLION$$$ to NASA

Right now 4.5 years is not a problem for Ares I as the budget is not available for faster development.

not true... the other time/money expensive part of the Ares-I (the 5-segments SRB) needs "only" three years, so, if you use an engine ready in a similar time, the first integrated (unmaned) system may fly around 2011 and the first manned Orion around 2012-2013 ... "That's one small step for Orion, one giant leap for NASA budget."
.


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#16 2007-04-18 09:05:52

cIclops
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Re: Ares-F : The French Ares-I

Fine, so you now agree that the idea of using the Vulcain 2 engine is now dead as it will cost more and will probably take longer than upgrading the J-2 smile

For some background information here are the development lead times for other spacecraft - note that Mercury, Gemini and Apollo were "crash" programs with no budget constraints

Spacecraft.....Contract...........1st manned
......................Issued..............orbital flight..........Lead time

Mercury.........Feb 6, 1959.......Feb 20, 1962.......3 years 2 weeks

Gemini..........Dec 22, 1961......Mar 23, 1965......3 years 3 months

Apollo CM......Nov 28, 1961.....Oct 11, 1968.......6 years 10-1/2 months

Apollo LM ......Jan 14, 1963......Mar 3, 1969........6 years 1-1/2 months

Shuttle..........Jul 26, 1972.......Apr 12, 1981.......8 years 8-1/2 months


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#17 2007-04-18 11:19:44

gaetanomarano
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Re: Ares-F : The French Ares-I

you now agree that the idea of using the Vulcain 2 engine is now dead as it will cost more and will probably take longer than upgrading the J-2

in my example, the Vulcain 2 is the "2007 ready airplane", while the J-2x is the "2010 ready airplane" smile

Shuttle..........Jul 26, 1972.......Apr 12, 1981.......8 years 8-1/2 months

your post adds further argument in support of my proposal, since, the Shuttle was planned to fly in 1976, while, its first flight was FIVE YEARS LATER, in 1981 ...well, the Orion/Ares 3+ years delay was added in the FIRST YEAR of the 15-years-long ESAS plan! ...just imagine the further delays this program will store in the next 14 years! ...the most optimists say that "3 years is the full amount of delays" but rational and experienced peoples know it's impossible with complex space programs like ESAS, so (at least) ONE+ further year of delay must be added before the first orbital Orion flight (then, in 2016) and (at least) TWO+ years for the (more complex) first moon missions (then, around 2022) ...that's why I suggest to SAVE time NOW (using ready available hardware) rather than LOSE years following time and money consuming projects like the 5-segments SRB and the J-2x... !
.


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#18 2007-04-18 11:50:23

GCNRevenger
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Re: Ares-F : The French Ares-I

Its beyond any argument that the SSME's unit cost was not the sole reason it was rejected, recall that the engine and associated facilities enjoyed nontrivial political support, so its cancellation did not come lightly. It is also obvious that the modifications to SSME, due to its complexity, would have been very difficult. Vulcain would suffer the same drawbacks. These modifications and associated testing would easily take just as long, if not longer, than upgrading the J-2 which already had vacuum/re-start capability. A year or so to work out details of the contract, a few years to make the changes, a few more years for testing...... Certianly, if it is going to take a year or two to man-rate the simple, previously-man rated, how much longer would it take for a complex engine like Vulcain?

And a word about contracts, that if it took a year or so to work out the contract for J-2 with American companies, how much worse would it be for Vulcain with a French company?

And if NASA's budget woes have added a one-year delay to the whole program in-total, even assuming Vulcain would be quicker to adapt for Ares-I/V, why would this make any difference to delay? You said the delay is for the whole program, so what difference does it make if you get the upper stage engine sooner? Also, the "fixed costs time = money!!!!11!!1!1!" argument is thus nonsensical.

I reiterate, why would having Vulcain radically accelerate the development of the rockets? The short answer is that it cannot, since the modifications for Vulcain will be time consuming as modifications to J-2, if not longer.

Ciclops is also correct that SSME, nor for that matter Vulcain, are presently capable of powering Ares-I/V upper stages. Both engines are ignited on the ground, both engines compromise vacuum for atmosphere performance, and neither engine can be restarted during the mission. J-2 on the other hand has none of these problems.

I also reject the notion that Ares-I/V with Vulcain will be "simpler" than with J-2X, the J-2 is remarkable for its simplicity, while Vulcain (like SSME) is a complex engine for maximized performance. It is also nonsense that the wounded French aerospace industry would simply write off the cost of a dozen or more of these engines.


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#19 2007-04-18 11:52:23

GCNRevenger
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Re: Ares-F : The French Ares-I

in my example, the Vulcain 2 is the "2007 ready airplane", while the J-2x is the "2010 ready airplane"

But Vulcain needs years of expensive modifications for use in Ares, so using this engine will not help accelerate the program.


[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

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#20 2007-04-18 14:06:40

gaetanomarano
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Re: Ares-F : The French Ares-I

...modifications and associated testing would easily take just as long, if not longer, than upgrading the J-2...

this is ONLY your opinion, NOT a facts... maybe, it's true, or it's true the contrary ...surely, both Vulcain 2 and SSME do EXIT now, while the J-2x must be (first) built ...maybe, the J-2x could be better for the job, but NOT the faster to fly

...if NASA's budget woes have added a one-year delay to the whole program in-total, even assuming Vulcain would be quicker to adapt for Ares-I/V, why would this make any difference to delay...

three points:
1. the +1 year delay was due to a modest(but essential) FY 2008 budget cut (around $500M, IIRC) so, saving money on the J-2x may restore the past timeline of the whole program
2. two of the three years of delay are entirely due to the time to develop the J-2x (twice+ the time of the 5-seg.SRB and +50% of the Orion) then, solve this problem, equals to solve 50% of the Ares/Orion timeline/budget problems
3. a big space agency like NASA is not a shop that can open if there are customers and close if there are not, it costs SEVERAL BILLION$$$ per years ALSO if it stops ALL its operations!
great part of the NASA annual costs are for the manned flights division... that money are well spent until 2010 while the Shuttles fly, but, after the Shuttle retirement, great part of these money will be (simply) wasted for NOTHING ...unfortunately, part of this delay can't be solved (since the Orion can't be ready to fly before 2012) but three of these five years of delay (2012-2015) with "zero flights - same costs" CAN be solved with a faster to build engine and a $500M money saving

The short answer is that it cannot, since the modifications for Vulcain will be time consuming as modifications to J-2, if not longer.

AGAIN, it's ONLY your opinion, not facts... maybe, you're right, but I prefer to hear this from the NASA and ESA engineers' voice!

...French aerospace industry would simply write off the cost of a dozen or more of these engines...

why not? ...ask them! ...for France,the "prestige" worth 1000 times the "money" and, drive the Ares-I with a Vulcain + land a french astronauts on the moon, surely IS a big prestige for France ...let's try! ...maybe, they will give you three dozens of Vulcain and (also) a free Tour Eiffel smile
.


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#21 2007-04-18 14:08:40

gaetanomarano
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Re: Ares-F : The French Ares-I

But Vulcain needs years of expensive modifications for use in Ares, so using this engine will not help accelerate the program.

AGAIN and AGAIN, it's ONLY your opinion, not facts...
.


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#22 2007-04-18 16:05:16

GCNRevenger
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Re: Ares-F : The French Ares-I

Nonsense, the modifications called for on SSME

  • ~On-board ignition system able to fire both in hypersonic air and in space after 1mo+ instead of normal igniters
    ~Modified nozzle for vacuum/near-vacuum only performance optimization
    ~Modified nozzle for reduced unit price
    ~Addition/modification of turbopump spinup systems
    ~Modified internal plumbing to enable multiple starts
    ~Addition of fuel tank settling systems
    ~Modified plumbing to enable vacuum start without the aid of atmospheric back-pressure
    ~Modified tank pressurization system
    ~Overall modification to improve thermal storage tolerance
    ~Overall simplification of turbopumps/preburners to lower unit cost
    ~Modified structural envelope and possibly addition of collapsible nozzle extender (eg RL-10-B series)

Not opinion, fact. These are all things that SSME would have to have to be a good option for VSE. These are ALSO things that a first stage engine, like Vulcain, would also likely require.

J-2 on the other hand only really needs #2 probably, a modified nozzle, and a bit more thrust squeezed out of the design.

I don't think you know much about the French aerospace industry. They are having trouble selling airplanes and rockets, and the French government doesn't have truck loads of money to bail them out. A nine-figure contract for selling engines to NASA is not something that is within the ESA's budget to just buy and give to NASA in return for a few seats on VSE.

Prestige is not so good unless they are your own countries rockets anyway, which is a good reason for NASA not to buy Vulcain to begin with irrespective of its other merits.

But I digress. Even if Vulcain requires half the modifications that SSME needs, it would still take longer to develop. Vulcain exists, but it is a first stage engine, so it is NOT usable for the upper stages. Not opinion, fact.

An upper stage engine has to operate in different atmospheric pressure, settle the fuel in the tanks, spin up the turbines, ignite in fast-moving air or vacuum, and fire several times. J-2 from the Apollo era had all these qualities built-in with a simple, reliable design. With modern upgrades, it will do just fine.


[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

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#23 2007-04-18 17:01:23

GCNRevenger
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Re: Ares-F : The French Ares-I

Oh by the way, both Germany and Italy also make major parts of the Vulcain, and the engine is assembled in Germany. You would have to make deals with all three of these countries and not just France.


[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

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#24 2007-04-19 08:20:14

gaetanomarano
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Registered: 2006-05-06
Posts: 701

Re: Ares-F : The French Ares-I

...fact...

no, these are no facts to support the J-2x vs. the Vulcain 2, it's ONLY the list of "things to do" and some (like the performance optimization and modified nozzle) are completely unnecessary since the standard engine's performance are good enough for the job and the price don't counts compared with the GIANT money and time saved thanks to an Ares-I ready to fly SOONER

if you add all the operations to have a working engine and slice every big operation in its smaller operations, you can post a list of THOUSANDS different (small and big) "steps" ...but that doens't matter, ONLY the "total time" counts

the problem is VERY VERY SIMPLE for those who WANT to understand it (and you don't seem to want to) ...

the early NASA plan in 2005 was to launch the first manned orbital Orion in 2012 (including the modified SSME) and the first lunar mission in 2018 but the SSME deletion from the Ares-I changed everything since the J-2x needs MORE time to fly and a bigger SRB

as consequence, the Orion (tested in 2011) will be READY TO FLY in 2012 while the integrated and man-rated Ares-I will be ready in 2014 (then, a modest budget cut shifted the full program of a further year) and, thanks to the 2 (past) + the 3 (new) years of delay, NASA will LOSE an OUTRAGEOUS number of BILLION$$$ for its manned flights' division without launch NO ONE astronaut between 2010 and 2015 !!!!!

the "non inevitable part" of this BIG gap (2013-2015) ALONE may cost up to $20 billion to NASA ...for NOTHING !!!

and don't forget the $2+ billion of EXTRA costs (3+ billion$ in total) to develop the 5-segments SRB !!!

the ONLY way to avoid this disaster is to change (NOW) the Ares-I design in three simple (and RATIONAL) steps:

1. deleted NOW the 5-segments SRB booster and go back to the (ready available, reliable, cheap and man-rated) 4-segments standard SRB for (both) the Ares-I and Ares-V

2. use the money saved ($2Bn) to cancel the $500M-budget-cut-derived-one-year-delay and SPEED UP the full ESAS plan

3. adopt NOW a ready available engine for the Ares-I 2nd stage just man-rating it and modifying for airstart/restart (if necessary)

...of course, NASA can follow the current strategy and damage/suicide itself...

last, the ESA, France, Italy and Germany decisions are NOT your problem... if they WANT give (also for free) the Vulcain 2 to NASA, they CAN

.


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#25 2007-04-19 13:57:37

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Ares-F : The French Ares-I

There you go again, waving your arms and ignoring the facts used to challenge your flimsy arguments.

Note the end of my last "blue" post, timestamp 4:50pm, is a short summary of reasons why the above list of reasons are largely needed to effectively substitute Vulcain for J-2X on Ares-I/V. To reiterate, an upper stage engine (J-2, RL-10, etc) must do several things that a ground start engine (RS-68, SSME, Vulcain) do not:

  • -Ignite in a vacuum or in supersonic air
    -Fire repeatedly (plumbing, tank repressurization)
    -Be optimized for vacuum/near-vacuum pressure
    -Settle free-floating fuel in zero gravity
    -Spinup turbopumps repeatedly
    -Withstand the hot/cold soak of space for 1mo+

Again, these are all special traits that Vulcain is not designed to do, because it doesn't have to. J-2 on the other hand was designed for these abilities from day one, and between the two engines J-2 is not nearly as complex as Vulcain.

You should also know that the nozzle is very important to the performance of the engine, because regular bell-shape nozzles common to all modern engines only operate well in either thick air or in a vacuum. For instance, most Hydrogen burning engines with nozzles optimized for vacuum firing achieve ~425-450sec, but a much worse ~300sec at sea level. Since the payload of Ares-I is important, it stands to reason that the maximum performance should be obtained from whatever upper stage engine is used. Since Vulcain fires at sea level, it stands to reason that its nozzle requires modification to maximize payload as an upper stage engine. Necessary to make the rocket fly? No, but necessary to make it carry Orion? Probably.

But I digress, even supposing the standard nozzle has acceptable efficiency and durability without significant alteration (recall that Vulcain-II had a nozzle failure on its maiden flight, and that this engine must be able to fire at least twice) the other modifications required to make it even minimally acceptable are more complex than the modifications needed for J-2. Air start? Restart? Zero-G start? Cold start? J-2 yes, Vulcain no.

Thus, the argument that we should purchase Vulcain to make VSE go faster is nonsense. It will not make Ares fly any sooner, and in all likelihood would take longer.

These are not minor changes, and serious changes will both require a lot of engineering and a lot of testing to make sure they work, much less be man-rated; which Vulcain never has been but J-2 has.

The original NASA plan was to fly Orion/Ares-I no later than 2014 with the minimum date of 2012, this sooner date was never the actual deadline like you make it out to be, but only what was possible given the funding outlook when VSE was written. Planners love to give ranges of times, and 2012 is simply the minimum possible date projected, not the date that "NASA thought" Ares-I should fly. This was also the date when SSME was the chosen engine, not when J-2X was, you cannot blame the supposed "delay" from 2012 to 2014-2015 on J-2X. Its not a delay, and its not due to J-2X.

Yes the gap between Shuttle and VSE will mean NASA will pay some of its large/expensive work force just to retain them, but your plan to use Vulcain won't reduce this one cent. In fact, it will probably cost more, not less, because Vulcain will need more modification than J-2.

Again, Vulcain is not readily available as an upper stage engine suitable for VSE.

Also, even if NASA did buy and modify Vulcain to power the Ares-I upper stage, its performance would only be EQUAL to J-2X. Not better, equal, so then you would still need the bigger five-segment SRB to push Orion. Furthermore, the bigger five-segment booster would not be available for Ares-V later on.

Let me say that again: you would still need the five-segment SRB even if you used Vulcain.


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