Reynolds Number

This video does an outstanding job of making the Reynolds Number meaningful. More about the use of the Reynolds Number in scale model testing in future posts!

David W. Taylor and the EMB

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Scale Model Testing

This video will give you a feel for what goes on in a model basin. Basically, what they are doing is testing a smaller version of a proposed design to see how it will fare under a range of conditions. The more they can discover and correct now, the more successful and reliable the full-sized version will be when it is put into use. This scale model testing is brought to you by William Froude, scale model testing pioneer.

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What is a Model Basin?

A model basin is a structure designed for the testing of scale model vessels. The tanks in a model basin can be used to test a scale model of the design of anything that is impacted by the principles of hydrodynamics before that object is built in full scale. Because of the Law of Similitude introduced by William Froude in the late 1880’s, we know that a model of a ship form can be tested under a variety of conditions and the results of those tests will accurately predict the performance of a full sized vessel of the same design. This testing allows the design to be perfected before construction of a full sized vessel is undertaken. Wait! There’s more!

Here’s to William Froude

It’s easy for us to look back and assume that everything went smoothly for those who were the first with an amazing idea. It’s also easy for us to miss the fact that ideas that are commonly accepted now were once wild ideas in the view of the established schools of thought. The most obvious examples are the ideas that were considered heretical by the Catholic church, but those were not the only ideas that brought ridicule to visionaries in their time. Sometimes the ridicule even came to men of science from other men of science.

williams_froude1One case in particular that I find compelling is the case of William Froude. Froude was the man who championed and proved that scale model testing could achieve results that were applicable to full-sized vessels. This is something we take for granted now, but in Froude’s time there was no proof. In fact, the Law of Similitude is based upon Froude’s groundbreaking work. So how did Froude get his shot at proving his theory? Wait! There’s more!

David Taylor

TaylorI’m tremendously interested in the ways technology evolved in the 20th century. There are so many things we use today that simply didn’t exist at the end of the 1800’s. And yet here we are, taking ocean voyages on vessels with gyroscopes to stabilize them, watching planes take off from the deck of carriers, lighting our world with bulbs instead of flames. For me, one of the most fascinating innovations of that time is the use of model basins for the testing of scale-models of ships before the ships were built –- a practice still in widespread use today.

At the start of the twentieth century, the US Navy needed to design ships of metal, with propellers and engines, to replace their fleet of wooden sailing vessels. Until that time the norm had been to build a ship and then see how it performed. This time, the Navy decided to follow the example of the navies of Europe and test scale-models first. But before they could test the models, they needed a place to test them. Wait! There’s more!

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