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Old 04-15-2008, 09:39 PM   #5 (permalink)
Join Date: Dec 2007
Location: Bay Area
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The Miata - '01 Mazda MX-5 Miata
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Originally Posted by Frank Lee View Post
I wanna know how that dude controlled the space Corvette in Heavy Metal. j/k!
What synchronism... I literally just saw that movie for the first time last night

Once you go supersonic and then further, how do aerodynamics become affected by sleek shapes ?
Just making sure it's clear - transonic and supersonic flow does not apply to cars...

So a huge amount of compression creates bow shock and eventually a shock wave (sonic boom). But, if the geometry cross section becomes smaller, there's a fan area (it's called fan something - I'm having trouble remembering the name). As the flow tries to expand into the smaller cross sectional areas, these little fan out ripples show up. Rockets have to deal with that AND turbulent flow separation (see the boat tailed bullet versus the non tailed version). IIRC, the expansion fanning is a source of aero losses...

I don't have too much info on superflow. But one of my professors gave an awesome analogy.... Imagine a crowded lecture hall - and class is done. 200 students are trying to get out of the two exit doors. The professor yells "coming through" and the students get out of the way as he passes. That's subsonic flow.

Now, imagine the same situation - but the professor doesn't say anything, and plows through everyone. How do you get more things out of the way? Make the door opening wider so things can compress out of the way.

This is why fighter jets have nozzles that get smaller (subsonic flow) and the space shuttle has nozzles that get bigger (supersonic flow). At least, this is how it was explained to me
Cars have not created a new problem. They merely made more urgent the necessity to solve existing ones.
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