I saw part of a thing on one of the learning channels that I hadn't seen in years. It was a thing developed by a flying missionary in South America, I believe. He had to do air drops of needed supplies in jungle settlements, and had no runway or parachutes. He developed a vertical drop technique, using a long rope, and flying in a tight circle. He could set his cargo down in someone's front yard. If you hang a weight on the end of a long string, and rotate your hand, the weight will tend to stay still. He would spiral downward til the box touched the ground, and release the rope.