I have a major in economics and I am creating an excel spreadsheet for quotations of sheet metal ductwork as my final thesis. I need to calculate weights for various types of ductwork produced in the company I chose for my thesis. In order to calculate weight, I need to know the surface area of ductwork parts. For many parts (pipes, elbows,etc.) I have figured out the formula for surface area myself, resp. found it on the internet. But there are some pieces I am not able to figure out how to get the surface area based on the input parameters.
You will find the pictures of the parts in the pdf attachment for which I need to get the formula for calculation of the surface area (in metric units). I would be very thankful if anyone of you could help me with finding the correct formulas.
Thank you very much for your time, help and effort.