Quote:
Originally Posted by theycallmeebryan
Just trying to make a plan of attack for this project. Tomorrow i think i'll pick up the framing supplies and try to find some cardboard for some CAD testing. I figure i can start by making the frame adjustable (ex: Be able to elongate the tail if i need to), overlaying cardboard, and tuft testing to find a good shape.
Also... I was thinking about the Side view of the bike, and it came to me that MOST of the air ill be pushing through will travel to the sides of the fairing and not overtop. Would it be safe to say that the shape of the side view doesnt matter TOO much? I know a 10-15* taper from the back of my helmet to the edge of the tail would be beneficial.
Would it be better to have the bottom half of the fairing the same exact shape? Here's what i mean visually.
So in other words, that whole black area (in side view) would be the NACA 0030-93 shape (in top view).
What do you guys think? |
I think you're right about the air traveling much more around the sides than up and over the bike. It's different in a car, because the car is so wide.
I think that the NACA shapes are a good starting point, but don't be locked into it. Be ready and willing to change your shape as tuft testing with your CAD fairings as more guidance than NACA theory.
And the first thing I'd be wary of is the length after the rear wheel. You're not making a straightline Bonneville speed bike, and with that short wheelbase, you're looking at some handling problems. I'd chop it off not far past where your photo ends in a Kamm shape, or at the very least, have a sharper upsweep, and bring the tail into a cone shape, rather than a fin.
You see the longer boattails on cars because of the inherent stability of 4 wheels on the ground. Having a long tail on a bike is going to give you the same type of weathervaning problems as an independently faired front wheel, especially with that short wheelbase.
Take it slow, use a lot of cardboard, and be very ready to change your design if it doesn't feel stable.
Stay safe!!