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The Iron Duke Resource Site |
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Welcome to my newly
redesigned Fiero 2M4 resource site. The original site recorded over
12000 visits, hopefully this one will also prove as useful.
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Road
Hugging Weight:
The
Myth
The
greater the vertical load on a tire the greater its friction with the surface,
therein lies the myth of road hugging weight.
If
you add mass to a car you first of all increase its momentum at any given
speed. Increased momentum also implies a greater tendency to continue in
motion in a straight line, inertia. This tendency quickly counteracts
(and overpowers) the increased friction afforded by the increase in vertical
tire load caused by the mass increase. Additional mass is not without
its advantages in certain automotive applications but handling response and
cornering power are not among them.
Tires
produce proportionally less increase in traction as vertical load increases.
This also flies in the face of the road hugging weight myth since the mass
increase soon overtakes the traction increase and reduces lateral
acceleration.
Vehicle
aerodynamics were in there infancy in the 1960s. Experimentation was
constant and new ideas were coming along almost daily, among these ideas would
be the most effective method of mounting a downforce wing. The Chaparral
racers pioneered a high mounted wing which was mounted to the hub carriers
rather than the chassis, soon Formula 1 racers were appearing with front and
rear adjustable wings mounted high above the car on struts which mounted in
the same way. Here we have the perfect solution, aerodynamic downforce
is applied directly to the wheels increasing the tire's vertical loading
tremendously, however the mass of the car is not increased so the momentum is
not increased. All of the vertical load translated into increased
lateral acceleration since there was no mass increase. The cars could
use softer suspension settings which made them ride better and cause less
fatigue for the driver. The system was short lived however since it was
seen as a safety hazard by some. The extreme stress on the hubs and the
sudden loss of grip if a wing strut broke were cited as major negatives.
Modern Formula 1 race cars use body/chassis mounted wings, this means the
force is now transmitted into the entire car, causing the springs to compress
resulting in the need for ridiculously high spring rates. This is why
you can see these cars bounce one wheel off the pavement when a bump is
encountered.
Wings
on street vehicles, such as the Fiero GT wing, serve little or no
function in downforce. The Fiero wing does however smooth the airflow
over the rear of the car and reduces aerodynamic drag. Spoilers do work
at lower speeds. A spoiler changes airflow over a surface in order to
prevent lift. The moral of this little story is forget about road
hugging weight, lighter is better, and wings may look cool but are only
effective if they are large and in the airflow, or at very high speeds.
I
Ira
Crummey
FIAT 850 Spider. An example of a nimble, light weight sports car of a simpler time. |
