Thus has more weight bearing down on the affected areas. The melting point of steel need not be reached- that is after all when it becomes liquid. It only needs to expand to the point at which it buckles.

Another thing: seeing as though the towers did collapse from the points of impact any hidden explosives would have to be from that point yes? Can you effectively protect explosives from the impact?

Also as for the Pentagon attack I gott interested for a time in that after that rather interesting film with the nice music. I didn't look into all of it ( and I'll probably still be a little worried until some of those other cameras turn up), but the thing about the size of hole can I think be explained.

The hole matched(or atleast was a lot closer to the size of) the weightier part of the plane: the floor of the main body. Remember that the Pentagon is rather sturdy. The hollow part of the plan is sheared off and hurtles forwards ( and of neccessity down) to be carried in the wake of the floor, which punched through the hole. The wings similarily shear off, finding the least resistance in going into the hole as well. Last bit might be plausible, the sources arguing it usually said that the wings following into the hole is well documented in other crashes.