[aerohead]

Originally Posted by Cycle

For the insulation... would it be enough to have the duct made of material that doesn't transfer heat well (fiberglass molded into the shape of a duct but made an integral part of the body panels), or would it be necessary to actually insulate it?

My plan was to make the ducts go down under the bottom of the bike. I'm not sure if the cross-over section could be made common between the two ducts (instead of two distinct and overlapping ducts)... it would seem it could be, since the air flow wouldn't really want to change direction very easily, it'd continue on to the opposite side of the cross-over section and out the opposite side of the bike.

The reason I put the vertical exit slits (I suck at anything artistic, so the drawing is understandably very rough) just past the widest part of the bike is because it sort of acts like an atomizer nozzle (venturi effect)... the air is just coming off its fastest speed at the widest section of the bike, then the body starts to narrow. Before the pressure has much of a chance to increase, the air speed is still fast, giving a sort of venturi effect upon those exit slits, and sucking the air out of them. Because the air exiting the ducts is better aligned with the narrowing section of the body, it'll stick to the body hopefully all the way to the tail, providing a thin wake that will then be filled with the warm air from the engine compartment, and the engine exhaust.

Because the ducted air is warmer than the surrounding air, its density is lower, which should help to lower skin friction drag a bit.

Would this work? It seems intuitive, but then, aerodynamics isn't always intuitive.



There'd still be a bit of flow in the ducts, which is why I angled them backwards at a 15 degree angle. They're not completely obscured in straight-line riding. I was operating under the assumption that at 75 MPH, a 15 MPH wind at 90 degrees to the bike is equivalent to a 76.5 MPH wind hitting the bike at 10 degrees, which effectively "opens up" the ducts at that angle to receive the full blast of that 76.5 MPH wind. But in straight-line riding with no cross-wind, a small part of the inlets would still be getting air, and you'd have the venturi effect described above.

It would be critical to acquire a pressure profile around the body envelope.You run the risk of air traveling forward through the duct instead of the other way around.
It's like running to the beach in a woody with the surfboards sticking out the open rear,and front windows rolled down.The base pressure is greater than at the A-pillars and exhaust fumes travel forward to the front seat area.Without wind wings flipped out to scoop air in,you're asphyxiated.