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Thread: What is acceleration?

  1. #1
    Rally Rat PAULBACH's Avatar
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    Question What is acceleration?

    Not sure how much of the following is true - but what a ride!

    "DEFINITION OF ACCELERATION" ... Fun Stuff !
    (courtesy of KB Performance Pistons)
    <- Source

    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 is working 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!

  2. #2
    BUBBAZANETTI
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    i've seen this batted around the web for a bit and this line always made me wonder:

    a fully loaded 747 consumes jet fuel at the same rate with 25% less energy being produced.
    sure, dragster's engines are quite powerful pound for pound, but a 747's 4 engines, depending on type, put out somewhere in the region of 240,000 lbs of thrust at full throttle, so there's no way a dragster is putting out 25 percent more "energy" (a vague term at best) than a 747.

    thanks for the post paul, i'll stop nit-piking now.

  3. #3
    Has the GS-Lust The_Veg's Avatar
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    My favourite line is

    and for once NOTHING BLOWS UP
    2012 R1200GS
    "If you can't fix it with a hammer, it's electrical." -somebody's dad
    http://www.thethingaboutcars.com/

  4. #4
    glennhendricks
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    Technically correct?

    Maybe?

    Energy in Jet A vs Nitro.

    As an engine fuel

    In a minor application, nitromethane is used as a fuel in racing, particularly drag racing, as well as for rockets and RC Models. In car racing, nitromethane is commonly referred to as "nitro" or just "fuel". The oxygen content of nitromethane enables it to burn with much less atmospheric oxygen in comparison to hydrocarbons such as gasoline:

    4CH3NO2 + 3O2 → 4CO2 + 6H2O + 2N2

    14.6 kg of air is required to burn one kg of gasoline, but only 1.7 kg of air for one kg of nitromethane. Since an engine‘«÷s cylinder can only contain a limited amount of air on each stroke, 8.7 times more nitromethane than gasoline can be burned in one stroke. Nitromethane, however, has a lower energy density: Gasoline provides about 42‘«Ű44 MJ/kg whereas nitromethane provides only 11.3 MJ/kg.
    So a cylinder of Nitro has twice the energy as a cylinder of gas. (11.3 x 8.7=98.31) vs 44.

  5. #5
    belquar
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    Quote Originally Posted by glennhendricks View Post
    Maybe?

    Energy in Jet A vs Nitro.

    As an engine fuel

    In a minor application, nitromethane is used as a fuel in racing, particularly drag racing, as well as for rockets and RC Models. In car racing, nitromethane is commonly referred to as "nitro" or just "fuel". The oxygen content of nitromethane enables it to burn with much less atmospheric oxygen in comparison to hydrocarbons such as gasoline:

    4CH3NO2 + 3O2 → 4CO2 + 6H2O + 2N2

    14.6 kg of air is required to burn one kg of gasoline, but only 1.7 kg of air for one kg of nitromethane. Since an engine‘«÷s cylinder can only contain a limited amount of air on each stroke, 8.7 times more nitromethane than gasoline can be burned in one stroke. Nitromethane, however, has a lower energy density: Gasoline provides about 42‘«Ű44 MJ/kg whereas nitromethane provides only 11.3 MJ/kg.
    So a cylinder of Nitro has twice the energy as a cylinder of gas. (11.3 x 8.7=98.31) vs 44.




    touche

    Your turn BUBBA.

  6. #6
    Has the GS-Lust The_Veg's Avatar
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    Quote Originally Posted by glennhendricks View Post
    Maybe?

    Energy in Jet A vs Nitro.

    As an engine fuel

    In a minor application, nitromethane is used as a fuel in racing, particularly drag racing, as well as for rockets and RC Models. In car racing, nitromethane is commonly referred to as "nitro" or just "fuel". The oxygen content of nitromethane enables it to burn with much less atmospheric oxygen in comparison to hydrocarbons such as gasoline:

    4CH3NO2 + 3O2 → 4CO2 + 6H2O + 2N2

    14.6 kg of air is required to burn one kg of gasoline, but only 1.7 kg of air for one kg of nitromethane. Since an engine‘«÷s cylinder can only contain a limited amount of air on each stroke, 8.7 times more nitromethane than gasoline can be burned in one stroke. Nitromethane, however, has a lower energy density: Gasoline provides about 42‘«Ű44 MJ/kg whereas nitromethane provides only 11.3 MJ/kg.
    So a cylinder of Nitro has twice the energy as a cylinder of gas. (11.3 x 8.7=98.31) vs 44.
    One problem- Jet A is not burned in cylinders, at least not anything resembling the type in which nitro is burned. What is the formula for converting the chemical energy in one fule in one type of machine into the equivalent for another type of fuel in another type of machine?

    If we really want to split hairs, we should go back to Derek's post and actually convert thrust to horsepower or vice-versa, since mechanical energy is what really counts here. It's the machine's way of doing work that the stuff in the first post was talking about. Of course the dragster will have a higher ratio of pwer to work performed, but that means that it is less efficient at getting its job done!
    2012 R1200GS
    "If you can't fix it with a hammer, it's electrical." -somebody's dad
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  7. #7
    Registered User R100RS's Avatar
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    I think the entire ignition system is around 88 amps, not 88 amps per spark plug, so the entire ignition system is comparable to an arc welder (of course, arc welders are available in a wide variety of sizes, but not down to 70W which is approximately what each of the 16 spark plugs would be getting).

    Just picking nits, here.

    I do love these top fuel facts. If the fuel they use was lined up in 1-gallon buckets, you couldn't knock them over as fast as the fuel pump(s) pump it.
    -Mike

    '02 R1150R
    '88 R100RS

  8. #8
    Not available in stores.. PAGoldsby's Avatar
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    Quote Originally Posted by PAULBACH View Post
    What is acceleration?
    The second derivative of position, with respect to time.

    I have just exhausted my sum retained knowledge of differential calculus.
    I can't believe how incredulous I am.

  9. #9
    BUBBAZANETTI
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    Quote Originally Posted by Belquar View Post

    Your turn BUBBA.
    here, and this is convenient since it uses a 747 for comparison, and answers ben's hp to lbs thrust conversion question:

    we calculate the power generated by the 747 to be 87,325 hp (65,100 kW).
    from:

    http://www.aerospaceweb.org/question...on/q0195.shtml

    in no way is the dragster remotely approaching that quantity of energy, in any form. thrust is all relative though, as the aircraft rarely requires anything approaching that max engine stand test thrust.

  10. #10
    Rally Rat PAULBACH's Avatar
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    Sure glad I quoted the source.

    You just couldn't make up stuff like this.

  11. #11
    Registered User dancogan's Avatar
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    Quote Originally Posted by PAULBACH View Post
    Sure glad I quoted the source.

    You just couldn't make up stuff like this.
    I just don't know where you guys find this stuff ... But then again, I don't know why I read it, either!
    Dan

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