Shekhar Singh wrote:A naive question to experts...
Can't we make stealth missiles( shaping, ram coating etc) so that weapons on external hardpoints do not increase RCS?
Making something Low observable involves shaping, and materials and being able to integrate with the overall design so that any design decision you make either builds on, or does no harm to decisions taken elsewhere. So hanging a stealthy missile off of a stealthy aircraft won't mean that it will retain its LO characteristics to the same degree as if it didn't have a weapon in the first place. The individual items may be stealthy, but what matters is how the missile, pylon and the aircraft perform when attached so it is those interactions that you have to measure not the individual signatures of each components independently. The enclosed pod that Srai posted helps with that in that you design the pod for best (possible) RCS when it is coupled with the aircraft shape and carriage. The weapons inside don't need modifications. But even then you are constantly trading one thing for another (the pod still has to factor payload, drag, maintainability, weapon loading/unloading requirements etc and so just can't be a pure RCS play).
Your clean 5GFA or 6GFA will be the best RCS you can get with that aircraft. When you start hanging stuff externally, even if it is via these pod like applications you deviate from what was originally designed though you can most certainly do your best to make those impacts as minimal as possible. In the end it all comes down to what the requirements are, and what you need for specific missions assuming that we are talking about multi-role/mission aircraft. On the F-35 for example, the Marines only required a gun for Close Air Support, which doesn't need stealth so they built it into a pod instead. Even though the pod does have shaping and materials for signature management (it is a multi-mission pod so has future applications beyond a gun) it will, in the net, adversely impact the aircraft's overall signature so it is a question of for what missions is this degradation acceptable and for what it is not. Same for the new external pylon they developed for the AIM-9X on the F-35. It uses shaping and materials but only mitigates the RCS degradation and not prevent it, but since AIM-9 on the F-35 is a "transition" capability, it is consider an acceptable interim solution. So these things are operator driven with missions in mind. You can definitely do things externally to reduce impact but you will never be as capable as you are when you are clean.