Duct Area Calculator
I wrote this calculator to assist in the placement of a splitter within a thrust or lift duct. Most times when you're designing a hovercraft, you have to split a percentage of air off into the lift system or skirt system. If you decide that you need to split off 33% of the thrust system air into the lift system and the duct is 72" in diameter, it is difficult to approximate the exact location of the splitter within the duct.
This calculator will help you place the splitter to within less than a square inch of the actual area required. This can be accomplished 2 ways. Both require that you know the exact center of the duct.
Cut out a cardboard circle the same diameter of the inside of the duct. Mark the center of the circle with a dot. Draw a line from the dot to the outside edge of the circle. Use a protractor to measure the angle returned as 'T' and make a mark at that angle. Draw a line from the dot through the angle mark and to the outside edge of the circle. Where the lines intersect the outside of the circles, is where the splitter is to be placed within the duct.
Cut out a cardboard circle the same diameter of the inside of the duct. Mark the center of the circle with a dot. Draw a line from the dot to the outside edge of the circle. Measure the distance 'D' inches from the dot along the line and make a mark. Draw a line though the first line at the mark representing 'D' inches perpendicular to the first line. Draw the second line completely across the circle from one side to the other. This will represent the location of the splitter within the duct.
Disclaimer: You are using information derived from the above program at your own risk. In other words, I'm not responsible for money lost resulting from the use of this page. It's for recreational use only.