Lanceur ARES

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Re: Lanceur ARES

Message par Invité le Jeu 14 Jan 2010 - 18:15

Jeannot, ISP = Impulsion spécifique.

Pour tout engin éjectant de la masse pour avancer, il est calculable.

Bien sur, sur, sur les propfan ou turboprops, ou le comburant est l'air, cela n'est pas très éducatif.

Par contre, sur les lanceurs, fusées, qui emportent à la fois carburant et comburant ( ergols )
il y a des comparaisons intéressantes à faire.

Si ( en gros ) la combinaison d'ergols ( H2 + LOx)est la plus exothermique donc la meilleure, les conditions d'application ( H2 maintenu à - 254 °C viennent contrarier ce bel équilibre.

Les RS-68 de Delta ont un ISP ( en secondes très bon ).
Mais ils sont 'jetables'..

Les SSME de Shuttle, utilisant les mêmes ergols ont un ISP de près de 40% inférieur, moins bon que celui des propulseurs Kero + LOx.
Oui, mais ils sont 'réutilisables', donc technologie bien plus couteuse.

Rappelons la règle de base :

ISP en secondes = le temps pendant laquel un KG d'ergols fournit un kg de poussée sous une pesanteur de1G terrestre ( 9,81 Newton).

La suite si vous le désirez..

Cordialement

TRIM2

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Re: Lanceur ARES

Message par Invité le Ven 15 Jan 2010 - 12:14

Bonjour à tous

La suite de l'importance de l'ISP, ne serait-ce que dans le projet Constellation ou son concurrent officieux Jupiter ne vous interesse t-elle pas ?

Cordialement.

TRIM2

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Re: Lanceur ARES

Message par Jeannot le Jeu 28 Jan 2010 - 13:56

Je ne comprends pas(plus) très bien ce qui se passe sur ces projets. Il doit bien y avoir un de nos membres qui pourrait éclairer nos lanternes.

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Re: Lanceur ARES

Message par Jeannot le Dim 31 Jan 2010 - 18:41

Voici quelqies liens vers des concurrents d'Ares (en dehors de SpaceX vu par ailleurs). Qu'en pense notre ami Trim2 ?

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Re: Lanceur ARES

Message par Jeannot le Jeu 4 Fév 2010 - 0:36

Une petie video sur le thème du "Il faut sauver le soldat Constellation" : [Vous devez être inscrit et connecté pour voir ce lien]

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Re: Lanceur ARES

Message par Jeannot le Mar 16 Mar 2010 - 8:56

Selon la Nasa, l'arrêt de Constellation coutera plus cher.

GREENBELT, Md. — The $2.5 billion in NASA’s Fiscal 2011 budget request to terminate the Constellation Program is probably “oversubscribed,” and will not cover all of the expenses expected to grow from shutting down the shuttle-follow-on effort.
Elizabeth Robinson, the former Office of Management and Budget career official appointed by President Barack Obama as the space agency’s chief financial officer, told the Robert H. Goddard Memorial Symposium here last week that the funds are not intended to cover contract termination liability — the cost to a contractor and NASA of shutting down contractor facilities, terminating leases and the like.
Instead, they will go for the cost to the government of pulling Constellation equipment out of its own facilities, environmental remediation at those facilities, and keeping civil servants on the payroll until new work can be found for them, Robinson said.
“The program termination costs and the civilian transition costs are the primary things in the $2.5 billion,” she said.
NASA has spent about $9 billion on Constellation to date — largely to develop the Ares I crew launch vehicle and the Orion crew exploration vehicle just completing preliminary design review. The Fiscal 2011 budget includes $1.9 billion in Fiscal 2011 and $600 million in Fiscal 2012 for the program termination and civilian transition costs associated with stopping it.
Robinson said NASA is developing a plan for managing the requested funds and handling the additional contract termination liability. She conceded the $2.5 billion has quickly become a potential cash cow within the agency as NASA struggles to change direction in human access to orbit from Constellation vehicles to a purely commercial approach.
“Everyone says that line will take care of it,” she said. “I think it will be oversubscribed.”

[url=[Vous devez être inscrit et connecté pour voir ce lien] Ending Constellation Will Cost More][Vous devez être inscrit et connecté pour voir ce lien] Ending Constellation Will Cost More[/url]

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Re: Lanceur ARES

Message par Jeannot le Mer 31 Mar 2010 - 6:44

Constellation continue pendant les débats au Sénat.

Constellation Continues As Congress Debates
The Obama administration’s effort to kill NASA’s Constellation Program has much of the agency’s workforce, except its attorneys, worried about their jobs.
In testimony on Capitol Hill, top NASA managers are walking a thin and carefully lawyered line as they prepare a White House-ordered shift to commercial human flights to orbit and long-term exploration-technology development in Fiscal 2011, while trying to obey a congressional directive that none of the funds appropriated in Fiscal 2010 be used “to cancel, terminate or significantly modify” Constellation contracts without the express approval of lawmakers.
“That provision is being strictly complied to,” says Administrator Charles Bolden. “We have not terminated nor canceled any contracts in the Constellation Program; we have not directed a slowdown of anything in the Constellation Program.”
Bolden and Doug Cooke, associate administrator for exploration systems, drew sharp questioning on the issue in back-to-back testimony on Capitol Hill March 23 and 24, and doubtless would have faced more had the Senate Appropriations subcommittee with NASA oversight not postponed a planned March 25 hearing on the agency’s Fiscal 2011 budget request. The new NASA plan has drawn almost unanimous opposition in Congress (AW&ST Feb. 8, p. 22).
As a result of the termination ban, work on the Ares I crew launch vehicle and Orion crew exploration vehicle in development under Constellation continues apace, while companies developing possible alternatives to Ares I/Orion forge ahead as well.
Alliant Techsystems (ATK) engineers are evaluating the results of a second test of the attitude-control motor for the Orion launch abort system, which would pull the crew capsule off a failing Ares I stack during ascent so it could parachute to safety. Preliminary results of the March 17 hot-fire test at Elkton, Md., show the test was successful, and the motor is ready to operate with ATK’s main abort motor and the Aerojet jettison motor in a pad-abort flight test coming up at White Sands Missile Range, N.M., this year.
Completion of the attitude-control motor tests came on the heels of preliminary design review for the Ares I/Orion stack, which cleared the vehicle to move on to detailed design, Cooke told the House Science space and aeronautics subcommittee.
“The Constellation Program will spend the next several months completing preliminary design reviews for its spacesuits, mission operations and ground operations and beginning detailed designs for future missions,” NASA states on its web site.
But, while work continues on Constellation, the two U.S. companies holding NASA commercial contracts to deliver cargo to the International Space Station are preparing the vehicles the Obama administration hopes will someday be able to deliver humans there as well.
Space Exploration Technologies Inc. (SpaceX) this month has hot-fired its Falcon 9 rocket on a converted military launch pad at Cape Canaveral AFS, Fla. (AW&ST March 22, p. 18), and Orbital Sciences Corp. (OSC) is building a new pad for its Taurus II vehicle at NASA’s Wallops Flight Facility, Va.
Crews at NASA’s Stennis Space Center in Mississippi are preparing to begin testing the AJ26 engine for the Taurus II at the end of May or early in June, following a successful long-duration test in Russia of the NK-33 engine that is its basis (AW&ST March 22, p. 36). For the American version of the Russian engine, Aerojet has added a gimbal block for steering, new initiators and electronics harnessing and is working with OSC to modify its duty cycle for the new launch vehicle, according to Julie Van Kleek, Aerojet vice president for space programs. A single engine will be tested at Stennis through the summer, to set up a two-engine stage test at Wallops in the late summer or early fall, she says.
Testifying to the House Appropriations commerce, justice, science and related agencies subcommittee, Bolden said he personally would like to “lease” commercial human-rated vehicles that NASA’s astronauts could pilot to the International Space Station, guided by a mixed team of NASA and contractor personnel at Mission Control Center-Houston. And he promised more details would be forthcoming on the plan for the shift from Constellation to the new effort to boost commercial transport to orbit.
“I understand the committee’s concern that details, such as our justification documents, have been slow to reach you,” Bolden testified March 23 in the first appropriations hearing on the Fiscal 2011 budget request. “Very soon we will be announcing program office assignments needed to carry out the president’s vision, and challenges to NASA. Other details will become available in the coming weeks.”
Those details still must clear the White House review process that apparently stymied releases of the full NASA budget along with the rest of the federal request on Feb. 1. Although Bolden took the blame personally for the uncoordinated budget release, members of the panel continued to express frustration that they still had not received a full explanation of the White House plan for the space agency.
For his part, Bolden says he favors development of a “common crew module” that could fly on several different commercial launch vehicles.
“I would like to help the commercial entities design a single crew module, because it’s good for us to train,” he says. “You don’t have to train crews for multiple crew modules, and that can be used interchangeably on any launch vehicle.”
Under pressure from Sen. Bill Nelson (D-Fla.) and others, Bolden has vowed to do what is possible within the constraints of the Fiscal 2011 budget to accelerate development of a heavy-lift launch vehicle. For NASA, that would enable human exploration beyond low Earth orbit. However, under questioning from House appropriations subcommittee members, Bolden said such a vehicle would also have national security applications.
“Just as recently as last week, I was involved in a video teleconference with the space-related agencies in our government, with Secretary [Michael] Donley, the secretary of the Air Force, and Gen. [Robert] Kehler [commander of Air Force Space Command], Gen. [Bruce] Carlson [director of the National Reconnaissance Office], and the issues that we discussed included the need for a broad national launch system that will put us back where we need to be,” Bolden testified. “We are too reliant right now on old systems.”
In addition to its review of the civilian space program conducted in the runup to the Fiscal 2011 budget request, the Obama administration is also in the midst of a broader interagency review of U.S. space policy under the aegis of the National Security Council. Interestingly, though, Defense Secretary Robert Gates and Navy Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, told House defense appropriators March 24 that they were not aware of specific concerns yet within the Pentagon over ramifications stemming from proposed changes under NASA.
Pressed by new defense appropriations subcommittee Chairman Norm Dicks (D-Wash.), Mullen said he and other defense officials have long-standing concerns about the space industrial base, much as they do for shipbuilding, but specific concerns apparently have not risen to the highest levels (AW&ST Feb. 8, p. 19).
While Bolden and other top NASA managers believe the gap in U.S. human access to space that will open after the shuttle fleet is retired can be closed more quickly and cheaply by commercial transport than the Ares I/Orion approach, Tom Young, the former president of Martin Marietta and executive vice president of Lockheed Martin, says he does not believe the record bears them out.
Referring to the Pentagon acquisition reform program known as TSPR (Total System Performance Responsibility) of the late 1990s, when the U.S. Air Force wrote its national security space contracts to give industry system responsibility, Young told the House science panel, “the results were devastating, and the adverse impact is with us today.”
Among examples of problematic programs developed at that time, Young cited the Future Imagery Architecture, the Space-Based Infrared System and the National Polar Orbiting Environmental Satellite System.
“These all started in the late ’90s, and not one of them has been launched to date,” Young says. “Today we’re getting half of the program content for twice the money, six years late.”
La politique de l'autruche... ou clairvoyance.

[url=[Vous devez être inscrit et connecté pour voir ce lien] Continues As Congress Debates][Vous devez être inscrit et connecté pour voir ce lien] Continues As Congress Debates[/url]

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Re: Lanceur ARES

Message par Jeannot le Sam 17 Juil 2010 - 8:38

Constellation est définitivement enterré mais lance un projet de fusée Heavy Lift tout en autorisant un vol supplémentaire de navette.

Key Panel Kills Constellation, Proposes Third Way

NASA oversight committee unanimously passed a bill July 15 that supports the Obama administration’s plan to end the Constellation Moon program — in name anyway — but replaces the White House’s proposed technology initiatives with a heavy-lift rocket program, continued support for the space shuttle and an Orion-like capsule capable of deep space travel.
The spending plan passed by the Senate Committee on Commerce, Science and Transportation keeps NASA’s overall budget for the fiscal year beginning Oct. 1 at $19 billion, as requested by the White House. However, rather than spending $6 billion over five years to seed commercial launch services for getting astronauts to and from the International Space Station, the Senate plan requests $1.6 billion over three years for commercial launch development.
“I think we address funding for commercial crew and cargo in a measured, responsible way,” said Sen. Kay Bailey Hutchison, a Texas Republican. “We do not overcommit taxpayer resources and do not leave our ability to sustain our $100 billion investment in the International Space Station entirely dependent on folks for rapid development of new providers.”
The bill also adds at least one more shuttle flight to the two missions remaining on NASA’s manifest. The extra flight would not take place before June 1, 2011.
The legislation directs NASA to begin work immediately on a heavy-lift booster, referred to as the Space Launch System, and a multi-use capsule that should be operational by 2016. Both systems should draw heavily on investments, equipment and contracts already in place for the shuttle and Constellation programs, in part to preserve the workforce and also to assure that if the United States needs to fly a contingency shuttle mission to the station, it has the capability to do so.
Commerce Committee chairman Jay Rockefeller (D-W.Va.), said he was told by leaders of the NASA Appropriations Committee that they support the new bill.

[url=[Vous devez être inscrit et connecté pour voir ce lien] Panel Kills Constellation, Proposes Third Way][Vous devez être inscrit et connecté pour voir ce lien] Panel Kills Constellation, Proposes Third Way[/url]

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