Quote:
Originally Posted by Flakbadger
I mean if you look at a regular bicycle vs a velomobile, you'll find that the aerodynamic fairing on the bike makes it vulnerable to lateral winds, which is why most velomobiles are tricycles instead of bicycles. Here's a quote from the wikipedia article on them:
"The fairing on a velomobile sometimes makes it more subject to cross-winds than a similar unfaired cycle. The effect of cross-winds is complicated because the force of the wind can act as a steering force, as-if the rider had tried to steer the cycle. "Wind steer" can be a safety issue and may also hurt performance, as a serpentine path is longer and thus slower than a straight line. Thus, a design with inferior aerodynamics may be better overall. For example, it is common for time-trial bicycles to use a solid disk rear wheel for best aerodynamics, and a spoked front wheel that has worse aerodynamics than a disk, but is less likely to steer the bicycle in a cross-wind." Something like a boattail that increases the length of the vehicle substantially could very well affect lateral stability from crosswinds, but I feel like the majority of mods centered on streamlining will not have a negative effect, since most of them focus on the front profile of the vehicle and decreasing the trailing wake. |
Dan Empfield (founder of Quintana Roo) has a lot to say about TT bikes--specifically, it's area in front of the steering axis that makes bikes susceptible to cross-wind instability. Even then, it's not as dramatic as people make it out to be; I run a 90mm deep rim--the deepest wheel you can buy today, surpassed only by the old Blackwell 100--on my TT bike here in the windy Midwest and have never had any problems.
Back to cars: Adding length at the back of the car with a boattail should improve stability--that added area is moving the center of pressure backward, which increases the tendency of the car to self-correct by steering back toward the direction of a crosswind. Bonneville cars incorporate tall fins (where class rules allow) for just that reason:
