I'm planning on adding hardpoints to the wing for my Jaguar, to support a couple of pretty large drop-tanks. (Approx 4" OD, 36" long each)

I always prefer to build hardpoints into the wing structure during construction in order to get good load spreading, etc - but since the wing in this case is composite and the inside is not hugely accessible (other than some limited access through servo hatches etc.) I'm looking for creative ideas from people who have done this kind of "add after the fact" stuff before.

My prior attempts on other wings have left me feeling tat there must be a better way, so I'd like to hear what methods have worked well for others.

Thanks in advance for your help,

Gordon

Gordon,
I hope I can explain this correctly, this is what I've done and it's super strong.
First, I decide how big my hard point is going to be, if it's just a dowel or something small, I'll just cut into one skin and glue the hardpoint in with epoxy/milled fiber, hysol, whatever. But if I want to have a larger area, I'll cut out basically a hatch as if putting in a servo, and then using either plywood, poly-ply etc, I'll build a lip inside the cutout area. Then I'll put in my blocks, glued solid to the upper skin, and have them cut so they'll glue to the bottom inside skin. Then I'll tape off the perimeter of the skin, and tape off the piece I cut out, run a bead of hysol all along the lip I glued into the cutout, put hysol all over the hardpoint, and glue the hatch back in, let the glue squeeze out of the cut line, wipe it off flush, peel the tape, and once it's dry, you barely need to sand it to get it smooth for paint, or in the case of a prepainted structure all you have left is a pencil thick line that doesn't need any sanding.
One other thing I've done for hardpoints, is if it's not going to be taking a huge load, and the structure is hollow enough inside (no spar in the way) is I will build a 1/8th thick ply plank with blind nuts on it for the mounting points, do the same hatch idea as before, but this time slide the plank into the wing (you will need to drill the 2nd hole in the skin and use a bolt to locate the plank), coat the plank with hysol, slide it in, bolt the rear hole in tight, clamp the front (where you slid it into the hatch area) and let it dry, then glue the hatch cutout back in the same way as described above.
Hope that made sense, without pictures it's tough to describe.

I found Bryce's method to be really strong and easy to do. Here is a link to his SM f-16 with composite wings. It's a couple posts down from the top.

Billy

http://www.rcuniverse.com/forum/m_48...17/key_/tm.htm

Thanks guys.

I've added 1/2" dia dowels in the past (just by making a hole in one skin and then putting the dowel and some minor supporting structure through the hole along with lotsa Hysol, and found that over time the skin deforms slightly because the load is not being spread far enough on a thin skin.

Perhaps Bryce's point about shoving some cloth in there first may be the key to wider load distribution, and prevent the need for a more invasive method. I may experiment on some "dummy" skins.