Boeing Unveils New Stealthy F-15Mar 17, 2009
Amy Butler/St. Louis, Mo. abutler@aviationweek.com
More photos are available at the Ares defense technology blog, and in a series of photos in our Defense Showcase gallery, starting here.
Boeing unveiled the prototype of a new variant of the F-15 Strike Eagle aimed at the Asian and Middle East markets that will incorporate stealthy coatings and structure here on Mar. 17.
Company officials hope the new aircraft will garner up to 190 orders, extending the F-15 line beyond the current backlog of 38 aircraft for South Korea and Singapore. Since the company lost the Joint Strike Fighter contest to Lockheed Martin, the future of its St. Louis manufacturing facility has been uncertain. Continued F-15 sales, as well as additional orders for F/A-18E/Fs and EA-18Gs, are the only work in the foreseeable future for the plant.
Major design changes in the new "Silent Eagle" version include internal bays within the existing conformal fuel tanks that can carry a variety of air-to-air and air-to-ground weapons. Each tank will be configured to hold two air-to-air missiles, including the AIM-9 and AIM-120 or a combination of the two.For the air-to-ground mission, 1,000- and 500-pound Joint Direct Attack Munitions can be carried or four 250-pound Small Diameter Bombs per tank. Weapons loadout can also be split between the AIM-120 and JDAM for a multirole mission.The Silent Eagle configuration includes 15-degree outward-canted V-tails - a shift away from the characteristic vertical fins of the F-15 that reduces the radar cross-section.
The Mach 2.5 speed of the Strike Eagle is maintained, but the cost is about 180-200 nautical miles of range capability because of the reduce fuel in the conformal tanks, says Brad Jones, program manger for F-15 future programs.
The new design includes a digital electronic warfare system (DEWS), made by BAE Systems, that can operate simultaneously with the aircraft's Raytheon active electronically scanned array radar.
Stealth coatings, though not yet applied to Boeing's prototype, could be added at a later time. Boeing says the coatings could contibute to an equivalent amount of front-aspect stealth as that offered by Lockheed's F-35. This includes reducing radar returns from sharp edges on the aircraft, including antennae.
Stealthiness for the F-15 was explored about a decade ago for the U.S. Air Force as an alternative to the Lockheed-led F-22, but was never pursued. "The internal carriage is what is new. The stealth is not," Jones says, adding "We are not really after the F-22 market or the F-35 market" with this new design.
The level of stealthiness exportable on the F-15 is up to the U.S. government to decide, Jones says. Though USAF officials have been given courtesy briefings on the Silent Eagle, talks on stealth exportability have not yet occurred.
A radar blocker for engine inlets, already fitted in F/A-18E/Fs, could be added depending on how much radar cross-section reduction is required by the customer and allowed by the government.
Jones estimates the cost of a Silent Eagle will be about $100 million per aircraft, including spares, if built new. A retrofit kit including the conformal fuel tanks, DEWS and coatings could be added to existing Strike Eagles, he says.
The target market includes South Korea, Singapore, Japan, Israel and Saudi Arabia, Jones says. The first likely customer is South Korea, which is looking for two new fighters, including its F-X Phase III program, which calls for 60 aircraft in the F-15 class.
South Korea's Agency for Defense Development is also pushing for a KFX program, which calls for about 120 domestically developed stealth fighters. Jones says coproduction of stealth materials would be subject to U.S. government review and a tough case to sell.
Japan and Saudi Arabia are also looking for new F-15-class fighters. And if the Silent Eagle were sold to the Saudis, Israel likely would want a chance to buy the aircraft too to maintain balance of power in the Middle East.
Boeing's willingness to integrate indigenous systems, such as electronic warfare suites, onto the Silent Eagle is an option that could be of interest to these customers - especially Israel. Israeli industry was recently rebuffed by U.S. officials unwilling to add foreign EW systems under the F-35 development program.
The weapons-carrying fuel tanks, which are affixed to the aircraft with two bolts, and can be removed within about 2.5 hours. Reinstalling the original fuel tanks restores the F-15 to its nonstealthy configuration, which is capable of hauling more and larger weapons, including anti-ship missiles.
The Silent Eagle prototype is based on F-15E1, the program's flight test aircraft. To date, it has been outfitted with the conformal tanks and the canted tails, which are for demonstration only and not structurally integrated. The actual canted tails would be added later if a customer requested them. Stealth coatings and engine intake blockers have not been added.
Jones says Boeing hopes to begin flight testing the weapons-carrying conformal tanks on the aircraft in the first quarter of next year. Design work on the Silent Eagle concept began in September last year in response to feedback from F--15 customers, he says.
Photo: Boeing
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