Howdy, I sent this once and didn't see it....try again.....
I'm building an MPS motorcycle and have a couple of questions...and
I would guess this would also pertain to cars.....
Concerning the fairing ( or car body), most of the ones I have
seen, seem to be solid to the air, in other words they don't allow the air
to enter the >inside< of the fairing/body, only direct the air around on
the outside. Now I know that there is an energy penalty from having air to
flow through a "dirty" enclosure, but would the bike/car benefit from
having a slightly smaller frontal area due to the air passing through the
bike/car rather than around it? could this internal air help to partially
fill the vacuum bubble behind the vehicle thereby reducing drag? would the
reduction of drag be greater than the drag from the ducting? should the
internal airflows be more "directed" by enclosing them with ducting and
thereby cleaning up the internal airflows or is there enough benefit from a
reduction of frontal area that there is no need for the ducting?
I realize that cars are going to have more of a problem with doing
an internal duct, due to the length, but motorcycles being shorter might be
helped.....I'm thinking of the P-51 radiator that made thrust from the
added heat from the radiator and the shape of the ducting. this might be of
some use to me with an aircooled bike.....
John Robinson, Mechanician
Mechanical Engineering University of Wisconsin
1513 University Ave.
Madison, Wi. 53706
608-262-3606
Current World Land Speed Record Holder
Bonneville Salt Flats
H/GCC 92 cu.in. 1980 Dodge Colt
144.396 MPH set 2000
MPS-PG 441 c.c. 1967 BSA Victor Motorcycle
95.193 MPH set 2001
Antarctic Ice Driller Oct02-Jan03
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