Fórum Defesa Brasil

Brigadeiro escreveu:

Skyway escreveu: Acabou de sumir um post meus logo abaixo do primeiro do Crubens nessa página...

CAMPANHA ANTI-FLOOD: OU POSTA KÔZA QUE PRESTE, QUE VÁ SOMAR, OU FICA SÓ LENDO. CHAT É NO MSN & QUETALES!!!

Colaborem, tigrada!!!(By Tulio)

Algumas coisas deixamos até passar, mas toda hora...


Até mais!

PRick escreveu:[ quote="Skyway"]

Luís Henrique escreveu: Não concordo.

Vc quer o melhor possível, então vamos comprar o F-22.

Vc quer um caça de 4ª geração PLUS, então o Super Hornet está na lista.

O Rafale pode ser um pouco mais rápido, mais manobrável em alta velocidade mas perde em manobrabilidade em baixa velocidade, perde em alcance e perde no radar.

O SH não tem o APG-77 do F-22 mas o APG-79 AESA do SH é superior ao radar do Rafale.

Então, não me venha com essa. O Rafale é um ótimo caça mas tem seus pontos fracos. Assim como o SH.

Um caça que fica muito próximo do Rafale em velocidade, manobrabilidade, etc e que possui um AESA deste porte e pode levar 12 AIM-120 e ainda possui um JHMD, provavelmente a MAIOR manobrabilidade instantânea para DogFight (ou uma das) e o AIM-9X, além de ser o caça número 1 da US Navy com mais de 400 encomendas, com certeza deve ser RESPEITADO.

Afinal, os americanos não são burros e não podem ser burros.

Mas, nesta fase do processo, qualquer um dos 3 eu fico feliz. O que oferecer a melhor transferência pelo melhor custo/beneficio é o melhor.

Perfeito de novo Luis!

Mas não adianta...nada faz o Prick sair do Loop. É deus no céu e Rafale na terra. Já já aparece ele "argumentando" os pontos fracos do Rafale falando que não existem e falando que o SH não tem essas qualidades, e que os armamentos top não vão vir, e que o F-22 ele aceitaria, e que isso, e que aquilo, e blá...

Some critics accuse the F/A-18E/F for providing not much more than an increased range and a larger bring-back weight for such a high cost. In addition, it is essentially a non-stealthy aircraft that will have to fly in a combat environment in which low-observability will be increasingly vital for survival.

Mr. D'AMATO. This document reaches a number of devastating conclusions:

First, F/A-18E design improvements may result in only a small increase in combat radius over the short-legged F/A-18C; and,

Second, F/A-18E design margins, already worse than the F/A-18C or only marginally better, if compromised during full-scale development, could result in an F/A-18E with range, payload, and maneuverability that is worse than the F/A-18C.

If correct, the taxpayer is being asked to fund a make-work project costing billions of dollars that will do little more than subsidize a handful of corporations over the lean times ahead while providing the Navy with no more capability than it had the day the F/A-18E/F development program started. In fact, the Navy will come up with less than zero, because the F/A-18E/F will certainly consume funding that might have gone to the AX or to ever-more desperately needed support aircraft.

Mr. President, all this being said, I have every confidence that eventually the Navy juggernaut will roll right over everyone who stands in the way of the F/A-18E/F. Attempts by the Senate Defense Appropriations Subcommittee to apply a brake to the program last year were brushed aside with alarming ease. If I've learned anything in 12 years in the Senate, it is that the Navy will not be denied.

While I may not be able to stop the F/A-18E/F, I can limit the damage to the taxpayer. Taking a page from the B-1B experience, let me put the Navy on notice today: I will offer an amendment capping the total cost of F/A-18E/F development to the first available piece of legislation the Senate considers. A cost cap will, at the very least, prevent the kind of misallocation of funds we saw with the A-12 program. Overruns simply will not be tolerated.

F-22, F-18E/F, JSF, and V-22: A Trip Report to Lockheed-Martin,
Boeing, and Bell-Textron by a Member of Congressional Staff

January 13, 1999

Comment: #223

Reference:

[1] Member of the Congressional Staff, "Report on Travel to U.S. Aircraft Manufacturers (Lockheed-Martin, Boeing, Bell-Textron)," November 1998. Attached.

The attached report describes the F-22, F/A-18E/F, Joint Strike Fighter, and V-22 from the perspective of a member of the Congressional Staff. It now circulating widely on the back channel comm circuits of Capital Hill. It contains lots of useful information.


The author also makes an interesting comparison of the F-18E/F to the F-15E. I have checked this comparison with some experts, and the author is indeed correct. My sources told me the F-15E powered by the Pratt &Whitney F100PW-229 can out-turn the E/F, out-climb it, out-accelerate it, fly further, carry a far larger payload, and compared to the E/F, has a more capable radar and infrared targeting system, as well as a much more sophisticated electronic integration of the displays in the front and rear cockpits than the two-seat F/A-18F model. The only thing the E/F can do that the 15E can not do is land on a carrier. Despite these differences, not to mention the fact that the F-15E began production 10 years before the E/F, the F/A-E/F costs one-third MORE than the F-15E. Surely the addition of a carrier capability did not require this kind of performance reduction at a higher cost after ten years of advancing technology. The cost-capability-time asymmetries suggest fascinating questions about productivity and technology, because both airplanes were designed and are produced by the same corporate culture in the SAME factory.

The author's purpose was not to address such productivity questions but to do general fact finding. I urge readers to study this report and its end notes. No doubt, you will have many other questions about the efficacy of the aircraft modernization program, not to mention the state of affairs in an aircraft industry plagued by over capacity as well as the "buy-before-you-fly" petrologies of front loading and political engineering.

Chuck Spinney

[Disclaimer: In accordance with 17 U.S.C. 107, the following material is distributed without profit or payment to those who have expressed a prior interest in receiving this information for non-profit research and educational purposes only.]

Reference

November 1998
Report on Travel to U.S. Aircraft Manufacturers (Lockheed-Martin, Boeing, Bell-Textron)

This report is organized by aircraft type.


F-18 E/F

Summary: The Navy plans to purchase 548 F-18 E/Fs.4/ The "E/F" nomenclature denotes a new model series of the F-18; the earlier model was the C/D. The E and C models are single seat; the D and F models are two seaters. The F-18 is also sometimes identified as the F/A-18 to denote its multi-role design as a fighter (hence "F") and as an attack (bomber) aircraft (hence "A"). The E/F model is an extensive modification of the existing F-18 C/D: new wings, fuselage, engine inlets, avionics, and more. Some call it a whole new aircraft.5/ This is an issue in itself: in the early 1990s the Navy argued that prototype flight tests were not needed because the E/F was just an "upgrade," and 1,000 C/D "prototypes" were already flying. More recently, after the E/F encountered some unpleasant surprises in early flight tests, the Navy changed its rhetoric to argue that these types of glitches are typical for "new" aircraft. The E/F is being developed and built by Boeing at the former McDonnell-Douglas facility in St. Louis, MO. Northrop in CA also has a major share.

The Navy's justification for the E/F is the improvements it brings over the C/D in range (approximate 20% improvement, up to about 450 nautical miles [NM]), payload (about 30% improvement, up to 17,750 lbs), survivability (5 times more survivable) and "bringback" (ability to land on a carrier with more under-wing stores: 5,000 lbs over the C/D's 1,500 lbs). Each of these improvement estimates is under dispute; the cited figures are based on Navy/contractor estimates, rather than the critics'.

Cost: According to Navy data, the 548 aircraft will cost $46.1 billion for R&D, procurement, and MilCon, or $84.1 million each. GAO calculated existing C/D's to cost about $44 million each: almost half the E/F. The Navy says the cost increase for the E/F will be more like 40%; the difference with GAO comes mostly from a different assumption about production rates.

Note that the percentage-improvements cited above in range and payload are one- half to three-fourths the cost increase, as calculated by the Navy. The cited improvements in survivability and "bringback" are much more, but there are caveats here; see below.

Test & Performance: The E/F has completed the first stages of its operational flight tests. There are public reports that the Navy test pilots judged the aircraft either marginal or unacceptable as a fighter and inferior as a dogfighter to the C/D model. There are also some reports of a problem with "bringback." The relevant test report is available, but only in classified form. Contrary to past practice for these reports, virtually the entire text has been classified.

The 20% improvement in range, cited above, is also in dispute. Not only is this reportedly an issue in the test report, but also different parties can (and do) manipulate the calculations, depending on their biases, by using dissimilar assumptions in comparing the C/D with the E/F: e.g. using different size under-wing fuel tanks, altering the mission scenario for one aircraft with more low level [fuel consuming] flight; compare the heavier, two seat D to the single seat E; use non- empirical simulation data compared to actual flight test results (which may actually be one of the elements in the E/F range comparison to the C/D), etc., etc., etc..

While the Boeing/McDonnell-Douglas representatives disagreed with me, I was unimpressed with the claim of a five-times improvement in survivability for the E/F. Much of this claim is based on the assertion that, while the F-18E/F is not a "stealthy" or low observable aircraft, it does have a smaller radar cross section (a common measure of radar delectability) than the C/D. (The purpose here is to reduce radar detection range.) There are, however, two major caveats: 1) the reduction of the aircraft's radar signature is only on the forward facing part of the aircraft, and the aircraft is unstealthy from the side or rear. This is an important consideration because in combat, radar searches can and should be expected from all aspects, and if you can get yourself nose-on to an enemy radar to reduce detection range, there's very often another radar "out there" in a different location. 2) Also, I understand that the reduced, nose-on radar signature is only for a "clean" configuration; that is when the aircraft is carrying no air-to-air and air-to-ground munitions, and/or extra fuel tanks. The under-wing stores have their own radar signature that will "light up" typical search and tracking radars. Thus, in what I would call a tactically useful configuration, the E/F would appear to have no meaningful "stealth" advantage over the existing "C/D."

Additional Observations: There is a disturbing juxtaposition between the F-18 E/F and the F-22. The F-22 is a "stealth" airplane; the F-18 E/F is not. The Air Force says stealth is a must for effectiveness in the early twenty-first century; the Navy says it is not nearly so urgent. The Air Force also counts "supercruise" as a must, and it has designed a lot of aerodynamic agility (high thrust-to-weight ratio and extreme maneuverability) into the F-22. The F-18E/F is not a "super-cruiser," and it's aerodynamic agility is described by many sources as a step backwards from the predecessor F-18C/D.6/ Some in the Navy will explain that dogfighter capabilities in the F-18E/F were consciously compromised to enable more effectiveness as a bomber. And yet, the F-18E/F has very modest range and payload as a bomber—compared either to the Navy's former bomber aircraft the A-6E, or the Air Force's fighter-bomber, the F-15E. One of these services is wrong, and one of these airplanes could be a mistake—their individual merits and weaknesses notwithstanding.7/

It is interesting to compare the F-18E/F to the Air Force's preferred fighter/bomber, the F-15E: the F-18E/F has substantially less payload, less range, less avionics, and it very probably is less of a performer aerodynamically—as a dogfighter. And, yet, at $80 million-plus per copy, the F-18E/F costs more than the F-15E, at approximately $60 million per copy.

Both of these aircraft are costly. Even the less costly F-18E/F will be the most expensive fighter, per unit, in US history in constant dollars—except for the F-22. At that price, the Navy will get a multi-role fighter-bomber with fighter characteristics that appear to be something less than the existing F-18C/D and with a bomber payload and range that compares unfavorably with current and past fighter-bombers and attack aircraft.

The eulogies over the F/A-18E/F may be fair enough but they conceal other aspects which have so far earned the Navyís new fighter a mediocre image. The General Accounting Office, watchdog of the US Congress, has at any rate never felt any inhibitions in its criticism of the programme in all its test reports. Although many problems such as the ìwing dropî (unpredictable dipping of the wing at intermediate angles of attack) were fixed during the tests, according to the GAO the pilots were unimpressed by the aircraft during field trials. The performance requirements were of course achieved, but all in all the operational effectiveness of the E/F was essentially the same as for the F/A-18C.

Other problems highlighted by the GAO are the low maximum speed and comparatively slow acceleration, especially in the transonic region. According to the GAO, this does not bode well, given the Super Hornetís planned role as fighter-interceptor tasked with the protection of aircraft carriers, and will make it difficult to withdraw rapidly from a combat situation. Only a more powerful engine could help here, yet the US Navy has no plans for an engine upgrade.

Also subject to heavy criticism are the high levels of vibration and noise below the F/A-18E/F wing. These defects, it is argued, will damage air-to-air and even air-to-ground weapons or, as a minimum, reduce their service life. The US Navy plans to resolve this problem by modification of the weapons.

And even if the manufacturer and the US Navy dismiss such criticism as carping over an essentially excellent product, it does not exactly make life easier for those whose job it is to woo export customers. Now that, shortly before the Paris Air Show, authorisation has been granted to present even sensitive technology such as the Raytheon active electronically scanned array (AESA) radar to potential customers, marketing activities are to be stepped up. Apparently the US Navy and Boeing have been trying to obtain clearance for over 40 countries.

soultrain escreveu:Para rematar o meu pensamento:

Todos os caças têm prós e contras, são melhores numas coisas e menos bons noutras. O SH até pode ser o mais adequado fazendo as contas, o que me chateia é tentarem fazer do SH o que ele naturalmente não é.

Se à partida aceitarem as limitações e tentarem minimiza-las com outros atributos (ex poder ser operado pela MB, Radar AESA melhor que o futuro do Rafale) tudo bem, acho que é por ai que devemos discutir.

[[]]'s

soultrain escreveu:Sábado Out 11, 2008 6:17 pm

soultrain escreveu:Para rematar o meu pensamento:

Todos os caças têm prós e contras, são melhores numas coisas e menos bons noutras. O SH até pode ser o mais adequado fazendo as contas, o que me chateia é tentarem fazer do SH o que ele naturalmente não é.

Se à partida aceitarem as limitações e tentarem minimiza-las com outros atributos (ex poder ser operado pela MB, Radar AESA melhor que o futuro do Rafale) tudo bem, acho que é por ai que devemos discutir.

[[]]'s

Mas meu Deus, não é possível admitirem que o EF é inferior em alguma coisa? Os defensores do SH que me digam três desvantagens super-trunfo em relação aos outros dois. Nem que seja nas jantes POWs, isto já ultrapassou o razoável, já passou a crença pessoal e isso eu não discuto.

[[]]'s

A fronteira de seu envelope (que os caças raramente atingem) pode ser um pouco menor, porém por tudo que tenho lido, é mais do que suficiente para dar conta do recado, principalmente aliado a sistemas e armas top.

Santiago escreveu: Comentários em azul. Como desconfiava. Prick estava em looping mode qd escreveu esse post.

soultrain escreveu:

A fronteira de seu envelope (que os caças raramente atingem) pode ser um pouco menor, porém por tudo que tenho lido, é mais do que suficiente para dar conta do recado, principalmente aliado a sistemas e armas top.

Ninguém disse o contrário, no entanto, no limite, o F-5EM também dá conta do recado, o F-16 MLU idem, aliás é a espinha dorsal da minha Força Aérea, Todos os três escolhidos dão, mas vamos falar todos o mesmo?

Enganei-me, queria dizer SH e disse EF, mas continuo à espera das desvantagens do SH, pelos defensores deste.

Não é assim tão difícil ver qual o comportamento do SH, é como olhar para uma mota todo o terreno e uma de pista, o ângulo, comprimento das suspensões não enganam. Numa aeronave é mais difícil, mas se olhar por exemplo, para o ângulo de "enflechamento" das asas, tem de imediato a percepção que aquilo não é um caça puro, mas um caça de ataque, depois com o resto dos dados é fácil.

[[]]'s

PRick escreveu:

Santiago escreveu: Comentários em azul. Como desconfiava. Prick estava em looping mode qd escreveu esse post.

Não o único looping por aqui é você, os problemas relatados são 02 categorias.

1- Pode ser sanado ou consertado em parte; o que ocorreu com o reprojeto da asa, que diminui o problema da aceleração transônica. Conserto parcial do problema das fadigas prematuras nas asas;

2- O que não podem ser sanados; características de vôo, como alta vibração em grandes velocidades e altos ângulos de ataque, além do extenso dano aerodinâmico nas cargas sub-alares, e a impossibilidade de usar AIM-120 na ponta das asas.

Portanto, não importa o ano, mas se o defeito foi ou pode ser sanado. A relatório aponta que seriam fabricados cargas sub-alares especialmente projetadas para serem usadas no F-18E, isso não é prático, na verdade um absurdo.

Assim, o F-18E continua, com os mesmo problemas de célula, somente reprojetanto de novo a célula. Então ele é o seguinte:

Ótimo de pilotar em baixas velocidades, na medida que a velocidade sobe, o desempenho cai de forma significativa, acima dos concorrentes, o mesmo vale para as cargas sub-alares, o caça perde capacidade de manobra acima dos concorrentes. Isso não tem solução, o caça é assim.

Isso é válido em 1992, 1999, 2001,... em serviço as asas reprojetadas, e 2006(limitação dos g´s por conta da fadiga estrutural nas asas e conserto parcial). O caça sofreu avanços siginificativos no campo dos sistemas, a célula é a mesma, com as modificações sofridas nas asas.

[ ]´s

Favorable wind tunnel results led to further refinement of one of the design options and a configuration that met all design goals. This configuration is the wing leading edge extension on the production F/A-18E/F.

The leading edge extension redesign effort is an example of the value that NASA provides as a center for national corporate knowledge in high-angle-of-attack technology and its application to solve major problems in the development of U.S. fighter/attack aircraft.

An F/A-18E/F structural vibration -- or flutter -- clearance test program was also conducted at Langley (Transonic Dynamics Tunnel, 1993- 95). Phase one testing insured that each pair of dynamically-scaled surfaces (wings, horizontal tails, and vertical tails) was clear of flutter throughout the scaled flight envelope. The second phase of tests was with and without stores (bombs, fuel tanks, etc.) mounted to the wings. These tests used the tunnel's unique two-cable mount system, which allows the model to actually fly in the center of the tunnel with assistance from a pilot in the control room. The tests verified that the aircraft was free from aeroelastic instabilities including flutter within its flight envelope.

Having identified wing drop as a problem in early 1996, the Boeing/Navy team performed wind tunnel tests and computational fluid dynamic (CFD) studies in an effort to identify the root cause. Though the cause of the wing drop was determined, knowing how to moderate the air flow separation differences between the left and right wings was not. A wide variety of solutions were explored.

During this period, Langley engineers suggested that the flight program apply a NASA-developed technology -- passive porosity -- to a small section of the upper surface of the wing at the point where the wing folds for aircraft carrier operations. This solution, refined by the NASA and Boeing team, resolved the wing drop problem and permitted the Department of Defense to authorize continued production of the aircraft.

Carlos Mathias escreveu:Então vocês digam a resposta a todas essas perguntas aí. Afinal, se vocês sabem tudo do avião, nada melhor que uma surra de dados técnicos perfeitamente embasados. Afinal "O assunto deve ser tratado com seriedade, e não do jeito que está..."

E como a seriedade pede, que se postem estes dados trazidos aqui com extrema seriedade e blá, blá, blá.

E não adianta bater em mim que eu não tenho mais torcida nenhuma.

Carlos Mathias escreveu:Então vocês digam a resposta a todas essas perguntas aí. Afinal, se vocês sabem tudo do avião, nada melhor que uma surra de dados técnicos perfeitamente embasados. Afinal "O assunto deve ser tratado com seriedade, e não do jeito que está..."

E como a seriedade pede, que se postem estes dados trazidos aqui com extrema seriedade e blá, blá, blá.

E não adianta bater em mim que eu não tenho mais torcida nenhuma.