PROCUREMENT: Boeing’s new F-15X may replace an aging fleet of F-15C/D Eagles.

The F-15X reportedly came out of an Air Force inquiry to Boeing and Lockheed Martin about fielding an aircraft that could easily transition into the service’s existing air combat infrastructure, specifically to help counter the Air Force’s shrinking force.

There were some caveats to the solicitation: it needs to be cost-effective, low-risk and not considered an alternative to the larger F-35 procurement program, The War Zone reported. It seems those requirements were met, based on the reported features.

The F-15X seems to make sense logistically, as an evolved version of an older fighter with plenty of trained ground crews, spares, etc. It also probably makes sense as as “second day” jet. That is, the 15X would perform more prosaic missions on the second or third day of a major conflict, after stealthier (but more maintenance-heavy) F-22s and F-35s get done the most dangerous, initial operations. And with more modern avionics than the aging F-15C/D fleet, the F-15X might fill in the gaps left by our too-small fleet of F-22s.

But that’s all conjecture, based on what little is publicly known so far.