There is an idea I've heard since I was a kid that involves the relative strength of spider web. The claim is that if it were something like an inch thick it could stop an airplane in flight. How true is this? What thickness would be able to stop a 747?
It all depends on the conditions. The mass of the plane, the velocity, the silk strain, the breaking stress etc. play a role. By taking very large webs in order of 1km diameter you might end up with such results. Taking larger masses and webs in order of the wingspan would give you values of many meters thickness.