Quote:
Originally Posted by aerohead
Years ago we talked about this,but maybe at MaxMPG which is now defunct.
In 1990,at World of Speed,a guy was there,who I believe had just received a MS in aeronautical engineering.He had a streamliner which had a sphere mounted on a shaft which 'preceded' the streamliner's nose.
The premise was that the streamliner would ride within the turbulent wake of the sphere kinda like a rocket-powered torpedo riding within some of it's own exhaust shunted out the nose,or a Russian ice-breaker with 'bubbler.'
I have no record that the bulb was a success.
It's possible that it was too small,and already embedded within the Prandtl surface of discontinuity,hidden from the source-flow.Don't know.
It's certainly possible to do such a thing,but with any crosswind component,it would lose performance,as the vehicle would no longer be occulted by the wake.
The other thing is that you're looking at at least a double-deformation of the forebody flow field and most messengers publish that air should make only a single pass over a structure with zero circulation,and zero separation.The bulb concept would kinda violate the rulebook.
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There is something similar called aerospike (not the rocket engine) that is used on some missile systems, which is a section of a sphere (dish?) on an extended pole at the nose of the craft. I've seen them used on sub-launched missiles to create a cavitation bubble that the missile flies thru until it breeches the surface, and have seen them also on atmospheric launched missiles, presumably for the same concept of pre-punching the hole in the air with a smaller frontal area and then letting the bigger body fly through the expanding cone of cavitated air created. if it could be made retractable, it could be worth a try in automotives.