why are the noses of rocket, shuttles, planes, missile(…) half spheres instead of spikes?
In: 5557
On a rocket a shape of the nose is irrelevant, because it’s gonna leave thick layers of the atmosphere shortly after start. It’s the shape that allows more payload and some aerodynamics. A blunt cone is enough.
For the shuttle the main reason for blunt shape is the thermal barrier. It’s the one coming after super-sonic barrier and is experienced at hyper-speeds. The shuttle have to slow down from orbital speed of 8 kilometers per second to a speed of a plane in order to land.
Sharp pointy shape have heat energy acting on the surface exceeding the limits modern materials can take. If you look at the heat diagram for a sharp cone, the side surfaces close to the tip and the tip itself take enormous amount of heating. Blunt shape for comparison can reduce the stress something like 6 times. That’s the only reason as far as I know. Sorry, I don’t have the exact numbers.
EDIT: expanded a bit.
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