Science Buddies: "Ask an Expert"

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Hello,

So I'm working on a research project in which I have to make about 12 submarines. The idea is that I'll be applying is as follows:

Here are five fish that I have taken into consideration. They lie in the top five range of 'fastest fish in the world'. Below are the images in order of their respective speed:


1. Sailfish 110 km/hr



2. Marlin 80 km/hr


4. Tunny 74 km/hr



5. Bluefish/Bluefin Tuna 70 km/hr

If you notice, the tread pattern on their skin is diverse from each other and this is one of my factors. Another factor is shape. As an exemplar, scroll up to the blue marlin's picture. It has a long sharp nose. Characteristics like these will be applied to their respective boats.

The aerodynamics of varying shape can be explored. The image below shows how lower the drag coefficient (which corresponds to bodies that are more streamlined), faster the object.

So I have to build a test model first and I thought I could use two plastic soda bottles (thumbs up plastic bottle). That will be the skeleton and I need to cover this with some material over which I can carve a type of tread or modify the shape. I was thinking of Linoleum but I'm not sure if this will work. Also, I have to add a motor and a propeller to make it move.

Does anyone have a better idea to build a simple submarine which can have its shape/texture modified? I was thinking of clay earlier but it was not water proof. The idea needs to be reasonable in terms of time and money since I don't have much time left and I have to make many.

Thank you.

This is an urgent request, please respond asap.

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This sounds like a very interesting but rather challenging project. I'm not familiar with either submarines or model making, but I have a couple of items that might be useful. First, as to making models, you might look into modeling clay, specifically polymer clay -- a material that will thermoset, e.g. harden permanently, when baked at a low temperature in a home oven. This is available at hobby shops or online, such as at the URL http://tinyurl.com/d9mrrfg
Second, I have found a few notions about high speed hulls using on the web. The place I always start with is Wikipedia. The most relevant article for your work seems to me to be at:

http://en.wikipedia.org/wiki/Teardrop_hull

From various Google searches I found some other, marginally interesting references as follow:

From

http://www.articlesbase.com/history-art ... 54970.html

“There are two forces that impede a submarine's speed underwater; skin friction and eddy-making resistance. To overcome skin friction the USS Albacore's hull was made as small in area and as smooth as possible. Overcoming the eddy-making resistance required the streamlining or removal of protuberances from the hull. Fins and control surfaces were streamlined. The USS Albacore had no flat deck and her conning tower was reduced to the sail configuration that foreshadowed today's fast attack submarines.”


From

http://www.myspace.com/80dis4me/blog

“Submarine Skin. Max Kramer, a German scientist who came to the U.S. after W.W. II, was a pioneer in studying how the dolphin is able to swim so fast. By all superficial data, it should not be able to reach the incredible speeds it does: 40 knots (about 35 mi.) per hour. The secret, Kramer found, lies in the skin, which, because of its structure, is extremely resilient. The skin undulates as the dolphin swims, reducing turbulence and friction. Somehow the dolphin creates a vacuum around himself, which causes less friction drag. From his studies, Kramer was able to help produce a synthetic dolphin skin, lamiflo, which could be used to cover submarines, vessels, torpedoes, and superspeed aircraft, thus increasing speed.”


From:

http://en.wikipedia.org/wiki/Max_Kramer

“Kramer left government employment in 1952 to take a position as Technical Director with Coleman Engineering Company where his work focused on the highly efficient movement of structures through fluids via creation of laminar flows. He often reported that on crossing the Atlantic he noticed dolphins have a shape implying laminar flow and that this was the inspiration for his research. However, he had been researching laminar-flow issues long before he came to the U.S. After ten years of effort he discovered that a compliant coating, such as the skin of a dolphin would dampen any turbulent tendencies resulting from movement through water. He claimed that a 30% reduction in drag was possible, but subsequent researchers were unable to duplicate these results, leading to what has been called "The Kramer Controversy." Over time, as more research on the topic has been conducted, scientists have gradually confirmed Dr. Kramer's pioneering views.

Lamiflo is or was made by U.S. Rubber Company.