Rafael has taken the body of the Derby beyond-visual-range air-to-air missile (BVRAAM) and stuffed a new motor and sensor to create the new I-Derby ER.
By Python_missiles.jpg: Tiradenderivative work: NatanFlayer (Python_missiles.jpg) [CC BY-SA 3.0], via Wikimedia Commons
The weapon is guided by a new solid-state Software Defined Radar (SDR), based on technology from the Iron Dome, which takes up less space internally.
The new space is then utilized by inserting a second rocket motor that kicks in during the final phase of the flight. Accelerating the missile further and increasing the no escape zone.
[thumb]http://aviationweek.com/paris-air-show-2015/i-derby-er-all-new-performance-0[/thumb]