F-15SE Silent Eagle (photo : Boeing)
Boeing Looks to First Silent Eagle Flight
With radar-cross-section (RCS) trials for Boeing’s Silent Eagle semi-stealthy F-15 prototype complete, company officials are now focusing on South Korea as a possible first customer.
The RCS testing took place during a two-week period last August and September, although Boeing has only just acknowledged it because of proprietary issues, says Mark Bass, vice president of F-15 programs.
The company is eyeing South Korea’s forthcoming F-X3 competition for 60 fighters as the first sales opportunity for the Silent Eagle. The South Korean parliament’s recent hesitancy about investing in all-stealth aircraft “validates our approach” with the aircraft, says Bass. The company is considering potential international co-development partners for a Silent Eagle conformal fuel tank, although no announcements have been made.
Boeing is developing the variant for international customers that already operate F-15s and are seeking additional aircraft. The system is a possible alternative for nations interested in the Lockheed Martin F-35 Joint Strike Fighter. The Silent Eagle is not as stealthy as the JSF, but it could provide flexibility for countries trying to stretch their defense dollars.
In the early days of an air campaign, the Silent Eagle can be outfitted with weapon bays suitable for carrying air-to-air and air-to-ground weapons that would be tucked inside conformal fuel tanks, thus reducing the aircraft’s front-quadrant RCS. The aircraft could then be reconfigured in hours to handle the F-15’s characteristic heavy load of weapons once early threats are removed and sustainment operations begin.
The RCS tests on F-15E1, an Air Force test asset leased to Boeing, took place at the company’s anechoic chamber in St. Louis. Various coatings were evaluated and a final candidate has been selected and applied to the appropriate portions of the airframe. Testing produced the desired results, he said. Bass declined to provide details on the coating or the precise RCS numbers.
The RCS testing took place with the standard vertical fins on the F-15, not the 15-deg. canted structures unveiled last year by Boeing (AW&ST Mar. 23, 2009, p. 29). Data needed about an optional canted tail can be gathered mathematically, Bass says.
The RCS testing is a step leading toward first flight, which is slated for late July. Boeing had planned first flight for the first quarter of 2010, but slipped the milestone to allow for the inclusion of suggestions from prospective customers regarding upfront design work.
Following first flight, the focus will shift to demonstrating the ability of the conformal tank to safely deploy an Advanced Medium-Range Air-to-Air Missile. The test is slated to be conducted at roughly 20,000 ft. at Mach 0.6, a benign scenario for the first shot. This demonstration will likely occur in July or early August, says Bass.
In the meantime, Boeing has applied for an export license and expects a ruling this spring.
Following the weapons demo, the team will turn its attention toward marketing and sales. Bass says the company has not tempered its hope of selling 190 Silent Eagles despite lackluster support from Israel, which is aggressively pursuing the F-35.
South Korea is expected to issue a request for proposals by early 2011 for new fighters. At a later date, Saudi Arabia may accept solicitations to replace up to 80 early model F-15s, says Bass. Singapore is also a possible customer.
Boeing has cited a rough cost for Silent Eagle of $100 million per aircraft, although that would depend on factors such as co-development plans that have not yet been established.