By Lee Tae-hoon
In March 2009, Boeing unveiled a stealth version of the F-15, dubbed the “Silent Eagle” (SE), in an apparent attempt to meet a growing global demand for radar evading aircraft.
However, Boeing, which is vying for Korea’s ongoing fighter jet acquisition program, has told Seoul not to expect a major retrofit of its F-15 aircraft, a senior military official said.
"Boeing said it does not recommend Korea to choose the upgrade option of canted vertical tails for the F-15 fighter jet, citing the low cost effectiveness of its proposed development plan,” the official said on condition of anonymity.
“Boeing argued that its test results show only a slight improvement through the modification of the tails.”
Canted vertical tails were one of the F-15SE’s two main features that Boeing proposed earlier to reduce the aircraft’s radar cross-section (RCS), an area that reflects a radar pulse back to a receiver.
Nevertheless, an industry insider argues that canted vertical tails, a shift away from the conventional vertical fins, are a crucial feature of fifth-generation stealth aircraft.
“Stealth airplane designs like the F-22 and F-35 have canted tails,” he said. “If you have a surface perpendicular to the radar beam, the reflection comes right back to you.”
The military expert said that any aircraft for a stealth mission should not have a vertical surface as it can “bounce radar beams back” like a mirror.
“I wonder why all of the sudden, (Boeing argues) stealth is not important anymore,” he said.
According to a press release by Boeing, one of the F-15SE’s key characteristics is “twin vertical tails canted outward 15 degrees.”
Boeing claimed that the new modification would not only improve the aircraft’s radar signature, but also reduce weight and enhance aerodynamic efficiency.
“Canted tails provide lift to the rear of the aircraft, which eliminates hundreds of pounds of ballast and increases range by 75 to 100 nautical miles,” the press release said.
Earlier, a senior Boeing official said his company would most likely propose canted vertical tails as an upgrade option, rather than as part of the package, to Korea, while refuting claims that it had suspended the development of the new feature.
An official of the Defense Acquisition Program Administration (DAPA) refrained from discussing details of Boeing’s offer, but confirmed that Boeing wants to limit the F-15SE’s stealth options to the conformal weapons bay, which allows aircraft to carry munitions internally.
The internal weapons bay was another main characteristic of the F-15SE along with the 15-degree outward-canted V-tails.
Boeing, which has won two previous fighter jet bids here, is competing for Korea’s latest fighter jet procurement program aimed at purchasing 60 advanced jets at $7.9 billion , with its U.S. rival Lockheed Martin and EADS, a leading European aircraft maker.