I fling mine with the wings leaning to the right a bit. The black O rings don't last to long so I bought slingshot rubber from Wallmart. Slice it into doughnuts. Depending how strong you want them governed by the length. Smaller,15 in. wingspan planes, about 1/8 in long. 25/30 in. span about 1/4 in. long. Lifetime supply, almost.
