I’ve seen some F-16s carry AMRAAMs on wingtips and Sidewinders on inner pylons. Doesn’t having the heavy AMRAAM on the wingtip, from a physics standpoint, put more stress on the wing than having the lighter Sidewinder on the wingtip instead? It’s usually AIM-9 on wingtips and AIM-120s on inner pylons.
Are you sure they were slammers and not shrikes (anti radiation weapon derived from the aim-7)
Declan
Yes, they were AIM-120s.
Until LSLGuy comes in and definitively answers the question (preferably with a war story or three), what I’ve read from googling around is that the AIM-120 on the wingtips of the LAU-129 equipped F-16, helps with ‘flutter’, and so that’s why AIM-120s are placed on the tips. Per this site, you can evidently stick the AIM-120 on any of the three outboard stations (per wing, so six total) on F-16s with the LAU-129 launcher.
I would think that placing the heavy AIM-120s outboard that far would appreciably increase the F-16s roll moment of inertia, which I would think would hamper the F-16s ACM envelope. Again, that’s something that LSLGuy might be able to go into detail about, depending on the sensitivity of that specific information.
Speaking ex rectum, if aeroelastic flutter is a phenomenon that is proportional to airspeed, then minimizing flutter at the expense of potential ACM ability might be worth it, if the mission calls for the greatest possible speed before using BVR weapons like the AIM-120. E.g., an interception mission: get the bird out there as fast as possible to engagement range and use the AIM-120 BVR. By the time the F-16 gets close to the ‘merge,’ the wingtip -120s should already be gone, and max speed isn’t something that would be approached in the ACM merge anyway, so no need for flutter help. But this is just me guessing.
In an odd way, I think it’s the reverse.
When you see an F-16 on the ground, the landing gear is holding up the fuselage, and the wings are hanging off of that. In the air, it’s the opposite; the wings are holding up the fuselage. Hanging something heavy, like a drop tank, under the centerline of the plane is going to increase the stress. Spreading the load out along the wing is going to reduce it.
Imagine you roll this plane into a hangar, drop some cables down from the ceiling and attach them to the wings, and hoist the plane off the ground. Do AMRAAMs on the wingtips still seem like a bad idea?
I suppose I should say that this answer comes from the same place as Gray Ghosts’s last paragraph, but that’s the way I’ve always understood it should work. And I think GG’s right that having more weight farther from the roll axis would increase the moment of inertia, but I’m not sure by how much.