主题：F / A-18E / F  - 好的去？来自：Chuck Spinney <(电子邮件保护)>[个人意见，不代表机构隶属关系]Thu，1998年4月02日根据报告，F / A-18E /ReportsReports F很好。让我们希望如此，但我认为在释放20亿美元生产之前需要解决的一些不确定性，但需要解决。注意John Douglass的评论：1。“我们现在完全可以证明它不是一个问题。而且我非常非常希望，到本周末，我们将推动第二次低点- 在F / A-18E / F上的生产增量。““绝对和完全”是一个彻底的不受产病短语，意味着翼滴是固定的。目前的解决方案以多孔翼折叠整流罩为中心。海军测试人员最近向计划办公室提交了关于这一整流罩的航班试验报告。我还没有看到它，根据一个来源（也没有看到它），只有一份报告副本。他说，他的理解是报告语言中有一些警告。如果是真的，Douglass的索赔可能被夸大。我认为有理由令人担忧。 The current version of the fix is not an pure application of wing porosity theory. A pure application would have a porous outer skin over a solid inner skin, with a quarter to half inch of dead airspace between them. This dead airspace would form a plenum, and the higher static pressure behind a shock wave sitting on top of the wing would push air through the holes into the chamber, where it would increase the pressure, and cause the air to flow out holes under the lower static pressure region in front of the shock. This outflow would thicken the boundary layer and create an aerodynamic effect similar to that of a standard wing fence. The key is that the phenomenon is a self-contained, self-adapting process that naturally seeks its own balance. If optimised properly, wind tunnel tests suggest it might even improve performance by reducing drag. Unfortunately, this configuration caused an unacceptable buffet. Now the Navy/Boeing team has modified the concept by eliminating most of the inner skin and using the wing fold cavity as the plenum. Ram air (air slamming into the airplane as it moves forward) pressurizes the plenum, entering the cavity from the front of the wing when the leading edge flap is deflected downward, and also from the bottom of the wing. The self adapting feature is replaced by steady-state ram air (dynamic pressure) flowing upward through the holes porous fairing in front the shock wave (and maybe behind it as well). The substitution of dynamic for static pressure is a very primitive mutation of an elegant idea based on naturally occurring differential static pressures--but the elegant idea will not work for the E/F for reasons unrelated to its theory. The ram air mod appears to reduce the wing drop and buffet to acceptable levels, but there is a price--ram air absorbs energy which means increased drag and the flow through the wing may cause a lift reduction as well. The question is how much. I do not believe the Navy has had enough time to determine the magnitude of the performance penalties. A source close to the program told me today that the engineers at Boeing are nervous and think they need a few more weeks to make more pressure measurements. These uncertainties may be a source of caveated language, if indeed, that language exists. 2. Douglass also said wing drop "never was a problem" ... and ... "There isn't an airplane today that doesn't have wing drop ... the F-22's going to have it, Joint Strike Fighter's going to have it, everyone's going to have it," Both of these comments are baseless hype. If it was not a problem, why did the Navy work its but off trying to fix it. Distracting attention to the F-22 and JSF (which have problems of their own) is a low-grade public relations tactic unbecoming to an Assistant Secretary of the Navy. Moreover, he has no basis for this charge. In fact it is utter nonsense. As one wind tunnel expert (who is very active in this area) told me, "If you take the time early in the design and wind-tunnel testing phase, you should be able to correct any lift curve anomalies and any asymmetrical characteristics. So, I think that an advanced fighter can be built without having wing/drop or buffet problems (they really are closely related)." In other words, if this plane had been properly tested in the wind tunnel, and then prototyped, we probably could have avoided this debacle. The wing drop problem exists because (1) the Navy chose to skip the protoyping phase by hiding the fact that the E/F had a new wing in 1992, inorder to skip Milestone I by claiming the E/F was a mirror-image modification of the C/D, and then (2) hiding the fact that it had an unacceptable flying defect inorder to get approval for Milestone II production in Mar 97. I am now convinced the roots of the problem go the changes in the wing made to get increased range in level flight (and maybe reduced RCS). The designers did not increase the fuel fraction enough to meet the range requirments. By milking the wing design for additional range, they made the flow fields more unstable during turning maneuvers. If I am correct, the airplane needs a new wing design--which is now economically impossible because a production break would be too disruptive to the political constituency that was created when it was prematurely put into concurrent engineering and manufacuturing development in 1992, and then deliberately expanded by a premature production decision in 1997.