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COMSUBBBS
Posts: 3669
Location: Kansas City Missouri | Subject: Science Stuff
https://www.onr.navy.mil/en/Media-Center/Press-Releases/2018/Navy-Developing-Ship-Coatings
https://www.youtube.com/watch?v=JeEV7x3iuSQ
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Master and Commander
Posts: 1576
Location: Wollongong, NSW | Subject: RE: Science Stuff
Only problem with these sorts of coatings is that they are easily damaged by contact with a foreign object - think of a pile or fender. The drag resistance at that damaged area is far more out of proportion than is the case for normal drag on a hull. My father worked on this type of stuff (and alloys) for advanced aircraft design. |
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Great Sage of the Sea
Posts: 853
| Subject: RE: Science Stuff
rover177 - 2018-06-25 2:39 PM
The drag resistance at that damaged area is far more out of proportion than is the case for normal drag on a hull.
I do not comprehend or understand what your saying. Can you elaborate (keep it simple, I'm a snipe) |
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Master and Commander
Posts: 1576
Location: Wollongong, NSW | Subject: RE: Science Stuff
The water flow (air flow - aircraft) over a surface will have drag from friction. That drag can cause heat and a loss of speed - more energy is required to travel at the same speed.
Anything done to change that airflow - intentional with aircraft flaps for example, will cause a change in performance. Small boat hulls are often designed for planing purposes - less surface area in contact with the water.
Think of a ship when it turns, the rudder is stuck out to one side and the water flow changes. With a smooth hull, the flow is uniform. If the hull surface is damaged, little eddies (circular whirls) will occur and this drag will affect the performance and at the same time, produce "detectable" flow noises; think of cavitation as an extreme.
On a pure hull, the coatings can be very worthwhile but the cost in money and time to keep the flow "pure," is generally not worth the effort. |
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Great Sage of the Sea
Posts: 853
| Subject: RE: Science Stuff
Aha, got it. Thanks |
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Science Stuff
