Would appreciate any tips on attaching a wood beam to a tree (that has no suitable limbs) that can support a regular playground swing (the kind that swings back and forth on one axis). Intended for a child to support no greater than 60 pounds.
Would a beam (ie 2 x 8) with angled brace work, something like this?
Maybe I lack imagination, but a swing exerts very strong loads on the beam in an 180 degree arc. I just can't see how you can possibly make a strong enough connection to the tree in all those directions. In fact, I'd bet it's near impossible. Anything you put there would probably fly off on the first try. The beam really needs to be supported at both ends, and it needs to provide resistance along the entire arc. I.e., you need an A frame at both ends of the beam. In your case, you might be able to use an A frame on the far end, and use the tree as the second A frame. Even there, though, you're talking about one hell of a connection to the tree that, IMO, is not easy to design. Consider the potential cost of failure (injury to a child), and it's a non-starter in my book.
An exception to the traditional A-frame design are thick welded metal swing frames that you might find in some playgrounds...basically a T with a swing on either side.