# Monthly Archives: January 2017

## Slide Rules of the Rocket Pioneers

I was watching a interview with Valerie Neal, Curator and Chair National Air and Space Museum, on CSPAN. The interview was focused on the history of rocket development in both the US and Soviet Union. Valerie was asked what was her favorite artifact at the National Air and Space Museum. She responded that she liked artifacts that were the personal items of the pioneers. In the case of space travel, she said that the slide rules of rocket pioneers Wernher von Braun and Sergei Korolev were her favorite artifacts. Both men used the same type of slide rule. As I looked closely at the slide rules (Figures 2 and 3), I realized they were the same brand – Nestler – as used by some engineers I knew as a boy. My slide rule was a Pickett, similar to that shown in Figure 1. Continue reading

Posted in History of Science and Technology | 4 Comments

## Futurama Quote on Largest Buggalo Ranch on Mars

I am a big fan of Futurama – its going off the air was as disappointing for me as discovering Firefly a few years ago and having only 14 episodes to watch. I love the fact Futurama often includes small bits of real math and science in its scripts. My all time favorite piece of math includes a blackboard showing an actual proof using group theory by Sweet Clyde in the episode "The Prisoner of Brenda." Continue reading

Posted in Humor | 2 Comments

## Effect of Earth's Curvature on Suspension Bridge Dimensions

I have received a number of questions recently on how the curvature of the Earth affects building construction. In general, the effects of the Earth's curvature are ignorable because most man-made construction is on too small of a scale to notice the effects of the Earth's curvature. One well documented exception is the Verrazano-Narrows bridge, whose design took into account that the bridge towers are 1 5/8 inch farther apart at the top than at the bottom. In this post, I will show how to compute this value. Continue reading

Posted in Construction, General Science | 28 Comments

## Larsen Ice Shelf and Potential Sea Level Rise

I just read an article about a large iceberg that will likely form in 2017 when a 5,000 km2 section of the Larsen C ice shelf (Figure 1) calves into the Antarctic Ocean. There is concern that the formation of this iceberg will remove a barrier that has been preventing the entire Larsen C ice shelf, with a total area of over 50,000 km2, from sliding into the sea. This is a massive amount of ice. Continue reading

Posted in General Science, News Fact Checking | 2 Comments

## Engineers Say the Darndest Things

When the humor comes from engineers, it is usually pretty dry. In our office, we keep a whiteboard that is filled with some of the choicest quotes from engineers. I thought I would share a few of them with you. In general, engineers do not want to see their names on the whiteboard because some of the statements are pretty lame. Continue reading

Posted in Humor | 1 Comment

## Temperature Sensing with a Bandgap Reference

I have decided that my next home electronics project will be a precision thermometer that I can read over the Internet. I will be mounting the sensor at my cabin in Northern Minnesota, where winter temperatures can drop to -40 °C or lower. During the summer, temperatures can rise to nearly 40 °C. My plan is to connect the unit to a Raspberry Pie that I use to provide remote monitoring and control. I decided that I going to use a Texas Instruments' LMT70 precision temperature sensor, which uses a well-known circuit called a Brokaw bandgap reference to measure the temperature of its die. Continue reading

Posted in Electronics | 2 Comments

## Some PT Boat Statistics

I was doing some reading about President John F. Kennedy (JFK) and was surprised to learn that he actually commanded three PT boats: PT-101, PT-109, and PT-59. His service on PT-101 was very short. His next command, PT-109, became famous because of its ramming and sinking by the Japanese destroyer Amagiri. Continue reading

| Comments Off on Some PT Boat Statistics

## Fact Checking Power Over Ethernet Marketing Math

I was reading a blog by a cable manufacturer (Belden) this morning on the advantages of using Cat 6 cable over Cat 5e for network installations going forward (Figure 1 shows a great example of network cabling). Normally, I see the cable manufacturers recommending Cat 6 to customers because it will allow them to upgrade to 10 Gbps Ethernet, at least for runs less than 55 meters long. Continue reading

Posted in Networking | Comments Off on Fact Checking Power Over Ethernet Marketing Math

## Good Example of Learning Curve Labor Cost Reductions

I am always looking for examples of efficiencies that can be attributed to learning curve and production volumes. Figure 1 shows an example from an analysis of war production in Germany during WW2. This particular example focuses on the labor required to build a Ju 88 multi-role aircraft. Continue reading

Posted in Management, Product Cost | 1 Comment

## Measuring a Chamfer Angle Using Gage Balls

One metrology operation I have had to perform a number of times is measuring a chamfer angle precisely – Figure 1 shows today's example. Many items are chamfered – even in electronics. For example, edge connectors on printed circuit boards often need to be chamfered to ensure that they do not damage the connectors they are being inserted into. Continue reading

Posted in Metrology | 2 Comments