What is the taper, length and thickness of rubber bands used by slingshot kings China and Deng Feihu?

The king of China slingshot used a flat rubber band with a length of 250mm and a width of 17mm (according to Deng's 7 kg, the thickness of the rubber band he used was 0.8mm). Taper refers to the ratio of the diameter of the cone bottom surface to the height of the cone. If it is a frustum, it is the ratio of the diameter difference between the upper and lower bottom circles to the height of the frustum. 1: 10 is to draw a straight line of 10 first, then draw a straight line of 1 at its endpoint, and finally connect the two straight lines to make a triangle. Finally, by marking, we can know that the angle drawing is stupid. Convert the taper and slope into angles and draw them with polar axes. Taper 1: 10 is 3 degrees. Using trigonometric function calculation. Taper refers to the ratio of the diameter of the bottom circle to the height of the cone. Draw a vertical line of 1 unit first, and draw a horizontal line of 5 units through the midpoint to connect the endpoints. Then use parallel capture painting.