SCIENCE CONCEPT:
- The importance of aerodynamics to automobile racing has
been known throughout most of the sports history. In particular, the
significance of aerodynamic drag has been known since the early days of
the Indianapolis 500 when streamlined shapes were commonplace for race
cars. However, aerodynamic effects were a secondary concern to engine,
suspension, and tire technologies. The effect of aerodynamic lift on a
race car was not examined in detail until the early 1960's. Today, the
production of an aerodynamic downforce (negative lift) is considered to
be more important than drag reduction.
STUDENT OBJECTIVE:
- The student will demonstrate and observe how the
aerodynamic downforce is more important than drag reduction in automobile
racing.
OVERVIEW:
- The student will compile data about the quality of speed and
performance over the years in automobile racing as the aerodynamic
downforce came into focus and improved the racing automobiles.
TEACHER TEXT:
- By the early 1960's speeds were increasing rapidly. In
an attempt to decrease speed and, therefore, increase safety, regulations
were enacted to limit engine power and tire size. Car designers were
forced to look elsewhere to give their team an advantage. The advantage
was found in aerodynamics. Not in the reduction of drag, but in the
production of aerodynamic downforce.
Most automobiles produce lift. As the speed increases,
the lift force increases and the car becomes unstable. In order to
counteract this problem, modern race cars are designed to produce
negative lift. The typical family sedan has a lift coefficient of about
0.3, while a race car can have a lift coefficient of -3.00. One can
easily see the significant amount of downforce that a race car can
produce.
There are a variety of methods used to reduce lift and,
ultimately, produce downforce. These devices range from spoilers to
ground effects. Their use depends on the type of racing and the
restrictions imposed.
The simplest devices available are front air dams and rear
spoilers. The flow under a vehicle is disturbed by the various drive
train and plumbing components. By reducing the airflow under the
vehicle, a front air dam reduces the drag of the vehicle. Also, the
pressure immediately behind the air dam is reduced which aids the cooling flow
across the radiator. At the same time, the lift is reduced at the front
of the car.
|
|
PREPARATION TIME:
- 20 minutes.
LESSON TIME:
- 45 - 60 minutes.
TEACHER PREP:
- Gather materials
WORDS TO KNOW:
- aerodynamic lift
- aerodynamic downforce (negative lift)
- drag reduction
- lift coefficient
- spoilers
- ground effects
- air dams
- dive plates
- strakes
- underbody
- channels
|
