Page 18 - PCA Metro NY Region POST | 2019-September-eMag
P. 18

 Passing on Track, Track Physics, Bi- cycles, and Trailing Throttle Oversteer
Passing on the track at a DE event
I’m going to start this column with some thoughts on passing other cars in Driver Education events. This is a very important
subject because the passing rules are the very basis of why DE events are so safe – there are hardly ever any car-to-contact incidents. First,
it is the responsibility of every driver on track
to look in the rearview mirror often and if there
is a car right behind you, to give the appropri- ate passing signal and let the other car pass you. If you think you are faster car than the one right behind you, let it pass anyway. You’ll get chances to re-pass him soon enough. Second,
if you are catching up to a car ahead of you and want to pass it, you must get reasonably close to it in order for the driver to realize that you want to pass him. If you linger behind that other car and don’t approach it, the guy ahead may simply not realize that you want to pass.
Visit html for a full list of the rules and etiquette on passing which I have developed. Please pay particular attention to the Courtesy Rule.
The Physics – you can skip this section if you don’t care to understand underlying mechanisms.
I want to add more to the discussion I had about Torque and Horsepower a few months ago
by presenting 2 thought problems. Consider
a strong coiled spring in its compressed state which can shoot a heavy weight 10 feet up in the air when it is released. In order to do so this spring is releasing a certain amount of energy, for which horsepower, ergs, watts and joules
are merely units of its measurement. For prob- lem #1, consider a crank-operated device with a 1-foot long crank-arm which is used to compress this spring. Mr. HeMan can spin the crank and fully compress the spring in 1 minute, since he can exert a constant force of 200lbs. His friend Mr. Wimpy is only half as strong at 100lbs force, so it takes him 2 minutes for the task. They both put the same amount of potential energy into
the spring but in different amounts of time – and that is the difference between torque and energy (e.g. horsepower). HeMan has twice the power of Wimpy. The torque is the instantaneous force, while the power (energy) is the force per unit of time.
Thought problem #2 is like #1, except that HeMan uses the standard crank with the 1-foot crank-arm, while Wimpy uses one with a 2-foor crank-arm. HeMan’s 200lb force becomes 200 lb-feet of torque, while Wimpy’s 100 lb force also becomes 200 lb-feet of torque due to the torque- multiplying effect of his 2-foot crank arm. Is this magic? No, it isn’t, because Wimpy has to pull his crank double the distance each revolution of his crank as HeMan does, so Wimpy still loses the power contest to HeMan. If Wimpy wants to equal the HeMan’s power, he will have to spin his crank at twice HeMan’s speed, which he probably can’t do. This is why a 1957 VW Beetle making 36hp can never be as fast as that year’s Corvette with its 283hp. It would have to have
a red-line of about 36,000rpm in order to do so, rather than the 4,000 it actually had.
(Continued on page 18)
Track Ramblings

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