Expert: Dan Liddy - 12/16/2005

Question
Is there any danger to, or any point at which, drafting behind
another car during a race would be unwise, or put you at adverse
risk?    Likewise, is there any aerodynamic "shifting" from drafting
that occurs at fluctuating speeds - higher/lower, and would those
dynamics be increased - or put the driver in more jeopardy - when
entering/exiting a turn?

Answer
Hi Paul:

Thanks for an interesting question.   

First, I won't try to comment on anything to do with pro level NASCAR racing. That's a highly specialized set of aerodynamics that very few laymen understand.

When drafting another race car down a straightaway, there is very little to worry about since both cars are traveling in a straight line. However, if you are the drafter (behind) you should be careful not to actually hit the guy in front. It usually scares the hell out of him, and could possibly cause a high speed loss of control. If the same thing happens in a corner, I guarantee a scary situation, and one that is quite dangerous.

Drafting in corners does very little other than cause concern. You would be better off to brake a little early, cruise into the corner smoothly keeping your momentum up, and pick up the throttle before your competitor. That way, you'll not only ease his mind, but you'll probably pass him shortly after the exit.

As far as varying speeds go, the dynamics don't change, but there is precious little benefit under about 70 MPH. There simply is't enough drag behind a car at that speed. However, I race mostly at the Sebring Florida track, and simply have a BALL on the long straightaways there.

Finally the technique. As you enter the straight, you pick the nearest car in front and line yourself up directly behind him. If the cars are equal you will find yourself slowly closing the gap between. When you get right up on his rear bumper, you then quickly steer the car to one side.  The sudden additional drag on his car will slow him enough that you should be able to effect a pass. If not, he's got more horsepower than you.

That's about all I can think of - - -if you have further questions, feel free to ask

Best of luck

Dan Liddy
Sarasota, Florida