11 replies to this topic

[ciaoduc1]

I was watching an NHRA event the other day and was confused by some of the ET's and trap speeds

4.97 @ 311

4.73 @ 323

4.82 @ 260 (blower fail ¾ track)

4.81 @ 308

How is it possible that the slowest ET had the second fastest speed?
The car that had the blower crap out had damn near the same ET as the fourth car but was almost 50 mph slower.
These times were Funny Cars by the way.

[Pioneer]

Start with tossing aside the assumption of constant acceleration and you will realize that many of those odd combinations of ET and trap speed are in fact quite possible (and common).

Take an extreme example.... say car number 1 accelerates to its maximum speed of 200mph in the first 100 meters. It then cruises all the way to the line. Say car number 2 accelerates smoothly all the way down the track arriving at its maximum speed of 250mph but only right at the quarter mile mark. Which one will have the shorter elapsed time?

Now imagine that those numbers are much less extreme and some strange looking combinations are quite possible.

In the end, the trap speed is interesting from a fan's point of view but irrelevant. ET is what decides the winner. And its basically all about acceleration. As you noticed... the car that blew up 3/4 of the way down the track still posted a respectable ET. The small rate at which it was accelerating at that point is not totally irrelevant, but is certainly less important than its acceleration over the first 100 meters or so (maybe even less?).

[ray b]

lots of reasons
a biggie is tyre hook up
a little slip at first gives a longer time
but if the car hooks and stops slipping
it can still get a hi trap speed
remember speed traps are just befor AND AFTER the 1/4 milr finsh line [about a hundred feet]
so speed means NOTHING first over the line wins

so many a slower top speed car can win on reaction time and hole shot alone

coasting at 250+ covers ground very fast too!

and some guys back off early to save a motor and or parts esp if ahead or the other guy fouls or blows
others keep the power on thru the speed trap AFTER the finish line

[ciaoduc1]

Take an extreme example.... say car number 1 accelerates to its maximum speed of 200mph in the first 100 meters. It then cruises all the way to the line. Say car number 2 accelerates smoothly all the way down the track arriving at its maximum speed of 250mph but only right at the quarter mile mark. Which one will have the shorter elapsed time?

That's a good question...I'm not sure.

[McGuire]

In drag racing, the announced speed is taken from a trap covering the last 66 feet of the 1320 ft. course. (A 5.0 second elapsed time represents an actual average speed of 180 mph over the entire course.) And of course the win light comes on for the car that reaches the finish line first, not the car that is going the fastest when it gets there.

If the car loses the blower belt just before it hits the speed trap 66 ft. before the finish line, it will kill the mph but not affect the ET nearly as much. And if an opponent can't catch and pass him in that last 66 ft, he can still easily win the race. There is another 66 ft. trap at half track, through which funny cars are typically clocked at around 270 mph. There is an additional trap for the first 60 feet of the course, which takes these cars somewhere around .9 second.

Also, the race starts when the green light comes on, but the clock does not start until the car clears the starting light beam. Which is of course how you can have a quicker ET but still lose the race. The real race is RT + ET (RT = reaction time).

In drag racing, the clock gives every car around a 12-18 inch head start in ET -- the distance it takes the car to "roll out" and break the starting light beam. If you "stage deep" or roll the car as far forward as possible before the start, you will show a better reaction time. If you "stage shallow," or just barely dab the starting light beam when you pull up to the line, the car will show a better ET because it has a greater running start through the ET clocks. There is more to drag racing than may meet the eye.

[Wuzak]

Car 1. By over 1.5s.

A question...Is the ET only the time from when the car breaks through the start line beam to when it breaks the finish line beam? Can't a car have a superior ET (in heads up racing) but still lose due to a poor reaction time?

[Wuzak]

Thanks McGuire. You answered my questions before I finished posting them.

[McGuire]

Here are the segment times and speeds for a typical funny car on a pass clocked at 4.780 seconds at 324.05 mph. (Gary Densham, Topeka qualifying 2004 round 1)

60 ft 0.911 sec
330 ft 2.305 sec
660 ft 3.282 sec 259.76 mph
1,000 ft 4.092 sec

[ralt12]

I received this in an email, and I'm not saying it's all true, but then I'm not going to confuse a good story with facts here:

A lesson in acceleration
------------------------------------
First, some useful info:


* One Top Fuel dragster 500 cubic inch Hemi engine makes more horsepower
than the first 4 rows of cars at the Daytona 500.


* Under full throttle, a Top Fuel dragster engine consumes 1½ gallons of
nitromethane per second; a fully loaded 747 consumes jet fuel at the same
rate with 25% less energy being produced.


* A stock Dodge 426 Hemi V8 engine cannot produce enough power to drive the
dragster's supercharger.


* With 3000 CFM of air being rammed in by the supercharger on overdrive, the
fuel mixture is compressed into a near-solid form before ignition. Cylinders
run on the verge of hydraulic lock at full throttle.


* At the stoichiometric 1.7:1 air/fuel mixture for nitromethane the flame
front temperature measures 7050 degrees F.


* Nitromethane burns yellow. The spectacular white flame seen above the
stacks at night is raw burning hydrogen, dissociated from atmospheric water
vapor by the searing exhaust gases.


* Dual magnetos supply 44 amps to each spark plug. This is the output of an
arc welder in each cylinder.


* Spark plug electrodes are totally consumed during a pass. After 1/2 way,
the engine is dieseling from compression plus the glow of exhaust valves at
1400 degrees F. The engine can only be shut down by cutting the fuel flow.


* If spark momentarily fails early in the run, unburned nitro builds up in
the affected cylinders and then explodes with sufficient force to blow
cylinder heads off the block in pieces or split the block in half.


* In order to exceed 300 mph in 4.5 seconds dragsters must accelerate at an
average of over 4G's. In order to reach 200 mph well before half-track, the
launch acceleration approaches 8G's.


* Dragsters reach over 300 miles per hour before you have completed reading
this sentence.


* The red-line is actually quite high at 9500 rpm.


* The Bottom Line: assuming all the equipment is paid off, the crew worked
for free, and for once NOTHING BLOWS UP, each run costs an estimated
$1,000.00 per second. The current Top Fuel dragster elapsed time record is
4.441 seconds for the quarter mile (10/05/03, Tony Schumacher). The top
speed record is 333.00 mph (533 km/h) as measured over the last 66' of the
run (09/28/03 Doug Kalitta).


Putting all of this into perspective:


You are riding the average $250,000 Honda MotoGP bike. Over a mile up the
road, a Top Fuel dragster is staged and ready to launch down a quarter mile
strip as you pass. You have the advantage of a flying start. You run the
RC211V hard up through the gears and blast across the starting line and past
the dragster at an honest 200 mph (293 ft/sec). The 'tree' goes green for
both of you at that moment. The dragster launches and starts after you. You
keep your wrist cranked hard, but you hear an incredibly brutal whine that
sears your eardrums and within 3 seconds the dragster catches and passes
you. He beats you to the finish line, a quarter mile away from where you
just passed him.

Think about it, from a standing start, the dragster had spotted you 200 mph
and not only caught, but nearly blasted you off the road when he passed you
within a mere 1320 foot long race course.


That folks, is acceleration.

[Bluehair]

I read an article claiming that at 300mph, there is enough drag on a top fueler to decelerate the car at 3 negative G's before they ever touch the brakes or parachute. I suppose this is true for any light weight vehicle that places more emphasis on downforce than drag.

[Greg Locock]

Well, I could quibble with terminology, but the jumbo jet fuel rate comparison is about right. Neat.

I wonder what the top speed of a dragster would be? much slower than a fully laden jumbo.

[Tmeranda]

Top fulers are one of the most impressive sights in auto racing. About the only think I've seen to equal it are the F1 boys on the brakes at the end of the long straight at Indy before turning into turn 1. They too are recording 4+G's.