Quote:
Originally Posted by bombloader
I think I was little confused by Bicycle Bob's post. He was referring to Cp of the car in the yaw direction, I took it to mean in pitch which is the only way I heard it talked about in pilot training. Got it now  So to make things clear, I was talking about what aircraft are designed to with the CP and CG in pitch for stability. Bicycle Bob, you were talking CP in yaw correct? Anyway, I still think I'm correct about the vertical fin though. Two reasons:
1) Directional stability(yaw) in a car comes from traction. Even race cars producing downforce are just trying to generate more traction. Therefore, CG in relation to wheel placement is probably more important than CG related to CP.
2) Observationally, I've noticed that the poorest handling cars in high winds are typically aerodynamically dirty ones like my Jeep. Cleaner vehicles seem to shrug of winds better.
Take my my nonexpert opinion for what its worth, it would seem strange if a well designed boattail actually decreased stability. If I had the problem, I'd probably question whether I actually achieved the drag reduction I aimed for. |
My thought is that CG and wheel placement will have a tremendous effect on the cars polar-moment-of-inertia,and how it handles under transient loading.------------ With respect to CG and CP,auto fatalities have been strongly linked to aerodynamic instability.Front-drive cars have an advantage with low-drag forms,as their mass is concentrated towards the front of the car,and relatively low to the ground,both helping to keep the CP behind the CG,and roll-moments to a minimum.---------------- As to boattails,I've never added more than 4-feet.That was an inflated structure on the T-100.It was good for 5-mpg with a half-tonneau.