Different missiles with different end goals. Derby ER is still a SRM with a second kick for end game kinematics while Meteor is designed around sustained higher speed compared to a standard SRM so it will fly out faster for a given range. A VFDR is designed to essentially create a slower degradation in velocity compared to a SRM post burn out but is throttelable while a second kick stage will still not prevent the loss in speed that you will see post first stage exhaustion.manjgu wrote:Derby ER is the poor mans Meteor.
Although one can essentially control the second pulse trigger and have it go off as soon as the initial motor burnout you will loose on range by doing that. There is an AIAA paper from Raytheon that looked at a dual pulse and multi stage AMRAAM, Liquid fueled Ramjet AMRAAM and the a VFDR AMRAAM. Before the USAF shifted focus to faster missiles that can get to a target faster the trade space clearly showed a preference for VFDR for best overall performance. Dual pulse was identified as the lowest risk and cost upgrade but inferior to a VFDR or other simpler ramjet applications. None of these are without a penatly of course. The Meteor is largely the same size as the AMRAAM yet carries with it a good 25% weight penalty so there is no such thing as free lunch.