PICTURES: Boeing unveils upgraded F-15 Silent Eagle with fifth-generation features

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Boeing today unveiled a new F-15 prototype aimed at the international market with such "fifth-generation" add-ons as radar absorbent coatings, internal weapons carriage and integrated digital avionics, plus featuring a distinctive V-tail.

Improving the fourth generation fighter’s profile on air-to-air radar is Boeing’s key goal for the F-15SE, which the company plans to offer to five foreign countries with an estimated market for 190 orders.

Radar absorbent materials added to leading edges are designed to soften the F-15SE’s head-on radar signature. Canting both vertical stabilizers by 15° is intended to reduce radar returns to the side.

f-15 silent eagle

 © Boeing

Finally, embedding missiles and bombs inside conformal fuel tanks also reduces radar signature in all directions, and allows the F-15SE to perform its warfighting mission even with “clean” wings.

Boeing claims the end-result is an aircraft that can match the frontal-aspect stealth profile of any fifth generation fighter in configurations cleared by the US government for export release.

“We know we can get to the US government release level for international customers,” says Brad Jones, Boeing’s manager for future F-15 programmes.

To be fair, Boeing acknowledges the F-15SE’s stealth improvements do not help against ground-based radar systems, which are critical for waging offensive strikes against opponents armed with surface to air missile systems. Lowering the F-15SE’s thermal signature - a critical stealthy feature for the Lockheed Martin F-22 - is also not part of Boeing plans.

But Boeing says the F-15SE is aimed at international customers more likely to use the aircraft for defensive, counter-air missions, rather than offensive strikes in defended airspace where all-aspect stealth is necessary for survival.

Despite the stealth improvements, Boeing insists the F-15SE would not tradeoff sensor or aerodynamic performance. The Raytheon APG-63(V)3 radar would remain canted slightly forward rather than tilted back, preserving coverage and range at the expense of head-on radar cross section.

Moreover, Boeing has designed the F-15SE to also function as a non-stealthy, multi-role aircraft with the F-15E’s full payload of 13,200kg (29,000lb) of weapons. The conformal fuel tanks with the internal weapons bay can be quickly removed after landing, allowing the aircraft to takeoff with a full payload within 2h.

Another key feature of the F-15SE is the electronic warfare system. Boeing has selected the BAE Systems digital electronic warfare system (DEWS), which includes a digital radar warning receiver, digital jamming transmitter, integrated countermeasures dispenser and an interference cancellation system. The aircraft could continue to jam enemy radars even as its own radar and RWR continues to operate, Boeing claims.

Boeing launched the F-15SE, initially dubbed "Project Monty", last September. The company-owned F-15E testbed was quickly modified with the V-tail and conformal fuel tanks to provide a ground-based demonstrator.

Flight trials for a risk reduction programme are scheduled to begin in the first quarter of 2010. The first aircraft could be available for delivery to foreign customers three years after a deal is signed. Boeing plans to offer the F-15SE to Israel, Japan, Singapore, Saudi Arabia and South Korea, with all being current F-15 customers.

Notionally, Boeing estimates the F-15SE’s cost, including airframe, spares and training, at $100 million each.

The F-15’s single-largest customer – the US Air Force – is not officially a sales target for the F-15SE. However, Boeing says that all of the stealth, avionics and structural upgrades can be retrofitted on any existing F-15E. Company officials have briefed three agencies within the US Air Force, including Air Combat Command, but only as a “courtesy”, the company says.