Boeing has withheld further internal investment for its F-15 Silent Eagle concept pending a series of business case reviews, a top executive says.
Until last week, programme officials had confidently predicted an F-15SE first flight from February to June next year, but those pronouncements may have been premature.
"We're not at a point [on F-15SE] where we have a definitive path forward," says Tom Bell, the business development director for the Boeing's Military Aircraft division.
Specifically, the internal funding to launch the flight-test programme next year has not been released, Bell says.
A final decision is expected within the company over the next four months, Bell adds.
Asked if Boeing required a formal action from a potential customer, such as a letter of request or request for proposal, Bell replied it does not. Boeing has previously identified South Korea as the most near-term potential customer, but its request for proposals is not expected to be released until mid-2010.
Aa go-ahead decision on the F-15SE depends on a comprehensive business case analysis performed internally, Bell says.
Bell also sought to lower expectations for the F-15SE's frontal aspect radar cross-section. While programme officials previously predicted that it would match its counterpart on the F-35 Joint Strike Fighter, Bell says that Boeing could not be certain.
"Until we get one on the pole and do the studies, that's all theoretical at this point," he says.
Boeing launched the F-15SE without a customer in mid-March in a roll-out ceremony in St Louis, Missouri, using a cosmetically modified F-15E Strike Eagle testbed owned by the company.
If approved to move forward, the F-15SE would be offered to export customers as an alternative to the F-35. Boeing has proposed structural modifications, such as altering a conformal fuel tank into an internal weapons bay and canting the tail fins, and introducing fly-by-wire flight controls and a BAE Systems digital electronic warfare system.
The internal weapons bay configuration could also be changed within 2h, Boeing says, allowing the F-15SE to perform its multi-role mission.
In this way, the F-15SE is only stealthy for the "5% of missions where you want low observability", Bell says.
Boeing is meanwhile continuing to seek risk-sharing partners as well as customers for the project, Bell adds.
"Our conversations with customers betray a deep interest in this capability," he says.