Dang Knutz, you popped that fun little balloon that they had going on. I still like my theory that the dragster could not beat the stock car because there would be a turn nearing the 1/4 mile mark.
Anyway, enough nonsense, I'm out the door to go see Sammy Hagar in his hometown of San Bernardion.[img]i/expressions/face-icon-small-happy.gif[/img]

 

I think everyone admits that the acceleration is non-linear. However, the predominant non-linear acceleration occurs in the first 1/8 mile. According to the following excerpt from "Anantomy of a Top Fueler"

The clutch is all locked up at about the 3 second point. In our scenario, that occurs almost exactly at the 1/8 mile point. So any additional acceleration is only due to engine rpm increases. So the non-linearity of the clutch no longer applies. Now I would suggest that given this information, the assumption that the acceleration is constant for the last 1/8 mile is probably pretty close. Futhermore, no one can prove that the acceleration is not constant in the last 1/8 mile for these particular example.

Now the more interesting point of this discussion is to figure a mathematically correct solution given the assumptions. Since all of our assumptions have been listed, what is the mathematically correct solution? Clearly, it is a quadratic solution assuming a constant acceleration as listed in my last post.
Bryce

 

Even Tho I didn't know what the price of cheese in China was when I posted this question. I want to thank everyone who attempted an answer even tho we knew It would of been an approximate at best. I have been watching Drag Races since the Mid Sixties, so when I heard the question I thought it could be fun.
Might be a good one for The Myth Busters.
Y'all have been great sports.

OK on to the next one. lol.

If the Pink Panther weighed 150lbs and the 1000lb elevator he was riding in fell 200' could he really............................................ .................................................. ............?

A little nonsence now and then, Is releshed by the wisest of men. =]

Ohhhh, ACE? NASCAR SUCKS! lol J/K =]

 

BryceGTX,
dude you are like Stephen Hawking!

I read before that NHRA top fuel cars are only limited by the required gearing. I guess they want the teams to squeeze all the HP outy of the motors possible. They said if they ran different gears those cars could be way faster! According to you guys the car "tops out" quick, just think of accelerating in the 2nd half almost as fast as the 1st 1/8

BTW way speaking of racing, Anyone catch Diesel truck pulls yet? Wow.

 

Thanks for the vote of confidence 01ds650.. I always enjoy a brain teaser [img]i/expressions/face-icon-small-smile.gif[/img]

 

Bryce,

Although I compliment you on your complete research, it did lead you a bit in the wrong direction. The "Anatomy of a top fueler" might seam like a good sorce for info, but it has not been accurate for a long time. I'm assuming since before the 300MPH mark was broken. I make this assumption based on the fact that it speaks of the fuel being "cut" with a 2-5% of alchohol, when in fact it has been an NHRA rule to run 90% ,or a 10% cut, for several years now. It also speaks of 5000 HP, when it is now estimated that they are currently making between 7000 and 8000 HP. [Estimated since no dyno could measure that amount of power].

Given the information that you found, your formulations are excellent. Unfortunatly, racing advancement has surpassed that info several years ago.

 

Hmm Knutz. The web site I looked at clearly alluded to speeds of more than 300 mph.

Now the only thing more HP does is make it so that the limiting factor in acceleration will be traction. That will make the clutch lock up sooner not later. As a matter of fact it seems that the engine must be crippled by reducing the spark advance (reduce HP) prior to clutch lock up because it will only result in wheel spin. If wheel spin is always the limiting factor, then it seems that only supports my argument that acceleration is constant in the last 1/8th. This is further helped by the flat torque curves of blown engines. Now if they are producing 2-3000 more hp and not going much faster, what does that say for progress???

BTW.. There are water brakes that will easily handle 7000-8000 HP. If those guys really wanted a dyno, it could be produced for them. They just need to go to one of the big Dyno manufacturers. It will cost them though.

Now getting back to the problem, it seems to me that the only reason to specify the 1/8 mile speed of 268 mph was so that we could make the assumption that the acceleration was constant in the last 1/8th. It seems to me that we can rattle on all we want about what happens at the strip... we must recognize.. this thread is about a math problem.. it is meant to be solved.

 

Ok I knew I heard this before and I found the document I read a year ago. It was on a customers computer that I did work on and kept a copy of it. This is a very cool write up and you can see how freebird came up with this question now.

One Top Fuel dragster 500 cubic inch Hemi engine makes more horsepower than the first 4 rows of stock cars at the Daytona 500.
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 (cubic feet per minute) 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 for 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 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 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 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 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 past 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!

 

OK Bryce, so we narrowed down the age of the information to some time between the 300MPH barrier being broken and the implementation of the 90% rule.

How you assume that more power is going to cause the the clutch to lock up sooner is a mystery to me. The reason for the clutch slippage is to prevent the HP from exceeding the traction. The more HP there is, the more the clutch must slip to maintain traction.

I didn't say that a dyno could not be made to handle the power, but currently there isn't one that can be used for these engines and/or chassis.

You have a solid grasp on the math, I'm not denying that. Your understanding of the operation of a top fuel car is the weak link. Just because a word problem is presented, does not mean that suffient information has been included to formulate an accurate math problem that can be solved. My point is simply that it can't be solved accuratly.

 

Not really.. I solved it with a spreadsheet.. I sent it to Freebird.. We know the cars maximum speed and its split speed at 660 feet. we also know max speed and the amount of time it takes the dragster to get from 660 to 1320 feet. It has to cover so many feet fer second.. In order to achieve this it has to accelerate to top speed shortly after the 660 mark. I can post you the dragsters interval speeds at whater distance between 660 and 1320 or time on the track. I could fill it in for every .001 seconds if you like. X distance has to be covered in X time.