A
modern day, sophisticated timing system is capable of measuring ETs as
precise as one-millionth (0.000001) of a second. However, all of the
ultra fancy high-tech fiber-optic and digital technology in the world
is useless if the driver can’t make sense of the data generated.
Aside from the elapsed times determining the outcome of the race, the
precise numbers found on your time slip are highly beneficial in
helping improve your driving skills. There
is no better place to begin this discussion than the starting line. A
common misconception of newcomers is that the ET (elapsed time) clock
begins when the green starting line bulb is lit. This is a false
misunderstanding. In fact, there are two separate time recordings taken
on the race track: reaction time and elapse time. The reaction time is
the time elapsed from the flash of the green bulb to the motion of the
vehicle as it completely leaves the starting line beam. If that seemed
a bit too much, let me refresh your memory and elaborate further.
Recall, timing sensors are triggered by the disruption of a photocell.
Lining the drag strip at strategic locations are photocells that
project an invisible beam that contacts a reflector (the orange cube)
on the center line. The disturbed beam triggers the timing system. The
stage light (second set of yellow incandescent bulbs just above the
first amber LED bulb) on the Christmas tree tells the starter and
fellow competitor that you are prepared and committed to running the
race. The stage light is activated by the starting line beam. The time
that passes between the green bulb lighting and the front tire of the
race car exiting the stage beam accounts for the driver’s
reaction time. A perfect reaction on a typical five-tenths (0.500) of a
second full-tree (three amber bulbs countdown sequentially in half
(0.500) second intervals) is 0.500 seconds, or more simply converted
today as 0.000 seconds. The Christmas tree has had a number of
facelifts during its nearly 50-year long stint as the standard method
of starting competition drag races. Throughout the 1950s and early
1960s, a flagman standing between the two race cars would signal when
the drivers were to launch off the starting line. The obvious dangers
and subjectivity of using a flagman contributed to the design and
implementation of the Christmas tree. The Christmas tree made its
formal debut at the 1963 NHRA Nationals. The Christmas tree originally
consisted of five-amber bulbs but was reduced to it’s now
standard three-amber bulbs in the mid-1980s. In 2003, the NHRA
introduced LED bulbs, replacing the once standard incandescent amber
bulbs.
The
Christmas Tree
Two basic Christmas tree
designations exist: pro tree and full tree.
The pro tree is used primarily in
heads-up categories (Top Fuel, Funny Car, Pro Stock, Pro Modified, Pro
Stock Bike, Top Alcohol Dragster and Funny Car, and Super
Comp/Gas/Street). With the pro tree, all three-amber lights illuminated
instantly.
The full tree is primarily used for
bracket-style dial-in races, when a staggered tree is necessary to
accommodate vehicles of sometimes vastly different ETs. Such categories
using a full tree include Competition Eliminator, Super Stock, Stock
Eliminator, Super Pro, Pro, Sportsman, and Junior Dragster. With the
full tree, each amber bulb illuminates sequentially, typically every
0.500-seconds.
Yes, there are exceptions to
these general rules of thumb. For instance, the majority of pro tree
races are contested on a 0.400-second tree, where 0.400-seconds
separate the yellow amber bulbs and the green bulb. The Super Street
(10.90 heads-up) category, however, is an exception as they use a
0.500-second tree.
Regardless of 0.400- or
0.500-second trees, the driver’s time slip will read perfect as a
standardized 0.000-second. To demonstrate, what was once a 0.500-second
perfect reaction time would now be a 0.000-second perfect reaction
time. The same goes for 0.400-second perfect reaction times. Thus, any
deviation from a perfect 0.000-second reaction time will be recorded as
a +/- 0.000-second.
