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[ShinySideUp]

A fellow rider sent this to me and I found it a compelling read...


'DEFINITION OF ACCELERATION'

One top fuel dragster 500 cubic inch Hemi engine makes more horsepower than the first 4 rows of stock cars at the Daytona 500.

It takes just 15/100ths of a second for all 6,000+ horsepower of an NHRA Top Fuel dragster engine to reach the rear wheels.

Under full throttle, a dragster engine consumes 1-1/2 gallons of nitro methane per second; a fully loaded 747 consumes jet fuel at the same rate with 25% less energy being produced.

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


With 3,000 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 (stoichiometry: methodology and technology by which quantities of reactants and products in chemical reactions are determined) 1.7:1 air/fuel mixture of nitro methane, the flame front temperature measures 7,050 deg F.

Nitro methane 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 halfway, the engine is dieseling from compression, plus the glow of exhaust valves at 1,400 deg 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 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.

Top fuel engines turn approximately 540 revolutions from light to light! Including the burnout, the engine must only survive 900 revolutions under load.

The redline is actually quite high at 9,500 rpm.

Assuming all the equipment is paid off, the crew worked for free, and for once NOTHING BLOWS UP, each run costs an estimate $1,000.00 per second.

The current top fuel dragster elapsed time record is 4.428 seconds for the quarter mile (11/12/06, Tony Schumacher, at Pomona, CA). The top speed record is 336.15 mph as measured over the last 66' of the run (05/25/05 Tony Schumacher, at Hebron, OH).

Putting all of this into perspective:

You are driving the average $140,000 Lingenfelter 'twin-turbo' powered Corvette Z06. 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 'Vette hard up through the gears and blast across the starting line and pass the dragster at an honest 200 mph. The 'tree' goes green for both of you at that moment.

The dragster launches and starts after you. You keep your foot down 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 1,320 foot long race course.

... and that my friend, is ACCELERATION!

[And now, back to regularly scheduled programing...]

[ka5ysy]

High power-to-weight ratio is a good thing

everybody on this board needs to go play with the new K1300 to experience acceleration

[famousperson]

I can do that on my R.

[vodka]

Its how quickly you can twist the wrist on the R1200R my man...Dragsters......hmmph!!

[bobw]

Pretty humbling, but very cool

[lewellen]

Nitro methane 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.

... but hydrogen burns clear.

So what's the white flame really from?

Good roads,

- John L.

[famousperson]

Nitro methane 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.

... but hydrogen burns clear.

So what's the white flame really from?

Good roads,

- John L.

Atoms emit photons when dropping from a higher to a lower energy state, as happens when a gas cools, so I don't see how hydrogen could burn "clear." What does that mean?

[lewellen]

Atoms emit photons when dropping from a higher to a lower energy state, as happens when a gas cools, so I don't see how hydrogen could burn "clear." What does that mean?

It means that a hydrogen-oxygen flame does not emit that much light in the visible spectrum. It's a highly energetic reaction, which is why it's used as rocket fuel. In fact, if you've ever seen a Space Shuttle launch, you've seen this. The boosters are solid fuel and the bright glow from them probably comes from Al particles. The main engines, however, run on liquid hydrogen and oxygen, and their flame isn't bright at all.

Much of the light given off in a hydroxy flame is in the UV; the remainder tends to be in the deep red. (See http://repository.kulib.kyoto-u.ac.jp/d ... 3fp096.pdf)

In any case, pure hydroxy flames are not dramatic; this is but one reason hydrogen gas leaks are dangerous.

So, I repeat, where's the bright white light coming from? There has to be something else in there other than hydrogen, oxygen and water vapor.

Good roads,

- Lewellen

[celticus]

"Atoms emit photons when dropping from a higher to a lower energy state, as happens when a gas cools, so I don't see how hydrogen could burn "clear." What does that mean?"

Holy Cow !! It's like we've got a science guy here or something!!!

Mark

[mattbr]

You are driving the average $140,000 Lingenfelter 'twin-turbo' powered Corvette Z06. 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 'Vette hard up through the gears and blast across the starting line and pass the dragster at an honest 200 mph. The 'tree' goes green for both of you at that moment.

The dragster launches and starts after you. You keep your foot down 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 1,320 foot long race course.

200 mph = 800 1/4 miles per hour = 3600 seconds / 800 14 miles = 4.5 seconds per 1/4 mile. Would a dragster that runds the 1/4 mile in 4.5 secs really catch up in 3 seconds, assuming that the 'vette is still accelerating (a little) ???

[lewellen]

200 mph = 800 1/4 miles per hour = 3600 seconds / 800 14 miles = 4.5 seconds per 1/4 mile. Would a dragster that runds the 1/4 mile in 4.5 secs really catch up in 3 seconds, assuming that the 'vette is still accelerating (a little) ???

From a dead stop, d = 1/2 a t^2, where d is the distance traveled, a is the acceleration, and t is the time.

At constant speed, d = v t, where v is the velocity.

So, we want to find the time at which the distance traveled by the 'Vette (moving at constant velocity) is passed by the dragster (assumed accelerating at a constant rate for the sake of simplicity). At that point, d is equal for both vehicles, so

1/2 a t^2 = v t, so t = 2 v / a.

v = 200 mph = 89.4 meters / sec; a = 4.185 g (average acceleration from numbers above) = 41.04 m / sec^2; and therefore t = 4.357 seconds.

So, yes, the dragster would catch the 'Vette, but only 0.071 seconds before the quarter-mile mark ... or just under 21 feet.

But that assumes constant acceleration of the dragster, and we're told it doesn't do that.

So let's assume the post was correct, and the dragster passes the 'Vette exactly three seconds after launch.

In that case, we go back to the same formula; this time, we know t (3 seconds), and we want the dragster's acceleration. Then a = 2 v / t = 6.078g. This is consistent with the dragster pulling higher g's at launch than at any other time during the run.

Isn't physics fun?

F=dp/dt is your friend!

Good roads,

- Lewellen

[famousperson]

"Atoms emit photons when dropping from a higher to a lower energy state, as happens when a gas cools, so I don't see how hydrogen could burn "clear." What does that mean?"

Holy Cow !! It's like we've got a science guy here or something!!!

Mark

I may have had the question but it is Lewellen that has the answers!!!

[famousperson]

"F=dp/dt is your friend!"

Er, is that "p" as in momentum? As in p = mv and a = dv/dt therefore f = ma = m dv/dt = dp/dt? I'd never seen nor thought of that construct before, or am I on the wrong track?

[lewellen]

"F=dp/dt is your friend!"

Er, is that "p" as in momentum? As in p = mv and a = dv/dt therefore f = ma = m dv/dt = dp/dt? I'd never seen nor thought of that construct before, or am I on the wrong track?

Got it in one - very nice!

[rambling discussion about particle accelerators deleted]

Good roads,

- Lewellen