Monthly Archives: October 2020

Relative Cost of WW2 US Fighters

Posted on 19-October-2020 by mathscinotes

A reader of this blog mentioned in a comment that cost might be a big reason for the US Army Air Corps (USAAC) switchover to the P-51 from P-38s and P-47s. I thought I would put together a quick report on the relative cost of the three main USAAC fighters. The cost of these fighters by year was available in the Army Air Forces Statistical Digest (Hyperwar Site). The approach to Extracting, Transforming, and Loading (ETL) the data are the same as I used to determine the on-hand numbers of aircraft (link). For those who are interested in the details, my workbook is available here. Continue reading →

Posted in Excel, History Through Spreadsheets | 2 Comments

Lake Water Temperature Report Using Power Query and FILTERXML

Posted on 18-October-2020 by mathscinotes

I have a cabin in northern Minnesota on a small lake where I have been staying isolated from the rest of the US while COVID rages around me.  I track various lake metrics like height relative to sea level, clarity, and temperature.  I gather this information into a report that I send to the other folks who live on the lake. In this post, I show how I put together a chart of lake water temperature vs time using Excel and Power Query. I also demonstrate how to use the FILTERXML function to parse some rather messy data. I find myself using FILTERXML for data parsing more and more. Continue reading →

Posted in Cabin, Excel | 1 Comment

US Army Air Corp Fighters on Hand During WW2

Posted on 17-October-2020 by mathscinotes

Many years ago, at the start of my career, I worked with an excellent safety engineer who had served in WW2 as a fighter pilot in Europe with the US Army Air Corps (USAAC). You could tell that flying was the love of his life. Though we were working on naval weapons systems, our lunchtime talks often focused on his experiences flying aircraft during the war. His war service began in a P-47 (Figure 1) and his unit later transitioned to the P‑51 (Figure 2). Continue reading →

Posted in Excel, History Through Spreadsheets, Military History | 3 Comments

APR of Payday Loan

Posted on 5-October-2020 by mathscinotes

I watched a video (Figure 2) that shows Rep. Katie Porter (Figure 1) grilling the Director of the Consumer Financial Protection Bureau (CFPB) Kathy Kraninger in regards to the calculation of a payday loan's Annual Percentage Rate (APR). This blog post will show how to compute the APR for the payday loan example Rep. Porter attempts to get Ms. Kraninger to compute. I am not sure Ms. Kraninger knows exactly what APR is. The questioning is a bit uncomfortable because Ms. Kraninger is in no mood for a math exercise and Rep. Porter is not going to give up. Ms. Kraninger clearly is uncomfortable, but her discomfort is nothing compared to the discomfort experienced by a payday loan customer. Continue reading →

Posted in Financial | 2 Comments