Acceleration

Discussion in 'Hangar Talk' started by mscard88, Nov 4, 2018.

  1. mscard88

    mscard88 Ejection Handle Pulled

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    Ever wonder why a Top Fuel dragster gets a rebuilt engine after each run? Stay with this article - even if you aren't a 'car nut', this is interesting. One Top Fuel dragster outfitted with a 500 cubic-inch replica Dodge (actually Keith Black, etc.) Hemi engine makes more horsepower (8,000 HP) than the first 4 rows of cars at NASCAR's Daytona 500. Under full throttle, a dragster engine will consume 11.2 gallons of nitro methane per second; a fully loadedBoeing 747 consumes jet fuel at the same rate but with 25% less energy being produced.A stock Dodge Hemi V8 engine cannot produce enough power to even 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 lockup at full throttle. At the Stoichio-metric 1.7:1 air/fuel mixture for nitro methane the flame front temperature measures 7050 degrees F. Nitro methane burns yellow. The spectacular white flame seen above the stacks at night is raw burning hydrogen, disassociated from atmospheric water vapor by the searing exhaust gases. Dual magnetos supply 44 amps to each spark plug, which is typically the output of a small electric arc welder in each cylinder. Spark plug electrodes are totally consumed during a pass. After 1/2way thru the run, the engine is 'dieseling' from compression and the glow of the 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 enough force to blow the cylinder heads off the block in pieces or split the block in half! Dragsters reach over 300 MPH + ... before you have completed reading this sentence. In order to exceed 300 MPH in 4.5 seconds, a dragster must accelerate an average of over 4 G's. In order to reach 200 MPH well before reaching half-track, at launch the acceleration approaches 8 G's. 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 9500 RPM. THE BOTTOM LINE: Assuming all the equipment is paid for, the pit crew is working for free, and NOTHING BLOWS UP, each run will cost an estimated $1,000 per second. 0 to 100 MPH in .8 seconds (the first 60 feet of the run) 0 to 200 MPH in 2.2 seconds (the first 350 feet of the run) 6 G-forces at the starting line (nothing accelerates faster on land) 6 negative G-forces upon deployment of twin 'chutes at 300 MPH. An NHRA Top Fuel Dragster accelerates quicker than any other land vehicle on Earth ...Quicker than a jet fighter plane ...Quicker than the space shuttle ...Or snapping your fingers! Currently The current Top Fuel dragster elapsed time record is 4.42 seconds for the quarter-mile (2004, Doug Kalitta).(I think the time is now closer to 4 seconds, as of Winter 2014.) The top speed record is 337.58 MPH as measured over the last 66' of the run (2005, Tony Schumacher). Update Running only 1000 feet (320 feet less than 1/4 mile) Schumacher lately did it in 3.7 seconds at around 332 mph with 10,000 horse power with 90% nitro-methane and 10% alcohol. They thought running a full ¼ mile would mean they would be going too fast to stop by the end of the track.Let's now put this all into perspective…Imagine this: You're driving a new $140,000 Lingenfelter twin-turbo powered Corvette Z-06. 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, on 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 exact moment. The dragster departs and starts after you. You keep your foot buried hard to the floor, and suddenly you hear an incredibly brutally screaming whine that sears and pummels your eardrums and within a mere 3 seconds the dragster effortlessly 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 it not only caught, but nearly blasted you off the planet when he passed you within a mere 1320 foot long race! That, my friends is acceleration.
     
  2. kc4wsd

    kc4wsd Pre-Flight

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    Incredible!
     
  3. Zeldman

    Zeldman Final Approach

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    I never drove a top fuel dragster but I did drive a front motor alcohol dragster. The absolute most violent accelerations I have ever experienced. I would have to force myself to breathe. I had three inch wide shoulder straps and the day after a race my chest and shoulders would be sore from deceleration as if I had been run over by a truck. At the end of the day I would rattle when I breathed. I can only imaging what the top fuel drivers went through.

    The drag races were usually on Sunday. After I had been racing on dirt Friday and Saturday night.
     
  4. Eric Stoltz

    Eric Stoltz Pre-takeoff checklist

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    Neat-o!
     
  5. kc4wsd

    kc4wsd Pre-Flight

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    The last sentence reminded me of one of my all-time favorite bumper stickers . . .[​IMG]
     
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  6. Kenny Phillips

    Kenny Phillips Line Up and Wait

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    Google Scott Kalitta crash to see why Top Fuel and Funny Car only run 1,000 feet. Since 2008 the NHRA doesn't recognize nitro 1/4 mile records. But the fans won't be disappointed; the horsepower has now been estimated to crest 10K! and you can feel it in your bones.
     
  7. Bill Jennings

    Bill Jennings Final Approach

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    I love interesting tidbits of information like this. A favorite of mine is the mighty F-1 rocket engine, used on the 1st stage of the Saturn series of moon rockets. The turbo fuel pump that supplied RP-1 and LOX consumed 55,000hp. Yes, 55,000hp just to drive the fuel pump, and it pumped 3900# of LOX and 1700# of RP-1 PER SECOND! And that's just one engine of five, holy crap!

    These are numbers that are hard to wrap your mind around...
     
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  8. Walboy

    Walboy Line Up and Wait

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    That was an interesting read.

    Ever go to a tractor pull? Those ain't yer grandpa's tractor off the south 40...

    Tractor.jpg
     
  9. mscard88

    mscard88 Ejection Handle Pulled

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  10. Cap'n Jack

    Cap'n Jack Final Approach

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    More than a little hyperbole there....
    They need to go through the liquid state first

    There isn't enough water vapor in the air to create that amount of hydrogen. What I would believe is that, if the mixture is run very rich, there is hydrogen being produced by this reaction: 2 CH3NO2 → 2 CO + 2 H2O + H2 + N2
    And the hydrogen produced by that reaction is what is actually burning in the exhaust. The carbon monoxide is also potentially burned as well.
     
  11. Dan Thomas

    Dan Thomas En-Route

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    A 747 engine makes a lot more than 8000 hp. More like 40,000.
     
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  12. Zeldman

    Zeldman Final Approach

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    He's off and flyin' as he guns the car around the track
    He's jammin' down the pedal like he's never comin' back
    Adventure's waitin' just ahead.

    Go Speed Racer
    Go Speed Racer
    Go Speed Racer, Go!
     
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  13. Sundancer

    Sundancer Pattern Altitude

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    . . ."than a jet fighter". . . .my Mazda accelrates faster than a fighter. Over the first 100 feet, anyway.
     
  14. pigpenracing

    pigpenracing Pattern Altitude

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    Not top fuel but I was ate up with racing before I started flying. a 021.jpg a 023.jpg a 025.jpg a 026.jpg
     
  15. texasclouds

    texasclouds Pre-takeoff checklist

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    It is quite impressive what man can accomplish.
     
  16. jkaduk

    jkaduk Cleared for Takeoff

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    Love drag races. Been way too long since I've been. And Pomona is just up the road.
     
  17. Tantalum

    Tantalum Pattern Altitude

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    Pretty cool, thanks for the post!

    One question I had, if anyone knows, is
    How are they measuring "energy" - is it via a dubious horsepower <-> pounds of thrust metric, or are they looking at KW, Joules, etc? Just curious because I've always been told that the jet engine is incredibly thermodynamically efficient.. surprised that under some situations an piston ICE is more efficient (same "energy" produced from less fuel) than a PW4000

    Anyone know?
     
  18. Brad Smith

    Brad Smith Pre-takeoff checklist

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    Drag racing software is available online that can calculate horsepower fairly accurately if you input your E.T/trap speed and car specifics. I’ve used it for both cars and motorcycles and it’s a lot of fun to enter the parameters and see what it comes up with.
     
  19. Cap'n Jack

    Cap'n Jack Final Approach

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    One really can't convert horse power and pounds of thrust. One is a unit of energy, the other is a measure of force.

    Given some of the other comments in the original post, it is a fun read but not really informative.
     
  20. Tantalum

    Tantalum Pattern Altitude

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    yes, that was sort of my point, I didn't know if they were doing some math just based on the energy content of the fuel or whatever.. cool article none the less
     
  21. Sac Arrow

    Sac Arrow Touchdown! Greaser!

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    It depends on the operating conditions. In theory, the Brayton, Otto and Diesel thermodynamic cycles are roughly equivalent efficiency wise in ideal conditions and all are less than the Carnot cycle. The Brayton (jet turbine) cycle favors continuous, hot burns with high delta p's between the outside and inside engine spaces, moving high volumes of gas, e.g. a jet airliner flying high. In reality, the inability of the materials to handle heat limits jet engine efficiency. They really aren't that efficient compared to piston engines. But they are light, and the light weight can offset some of the inefficiency.

    In general, gas turbines inside tanks (e.g. Abrams) and small ships have a significantly higher fuel burn than their diesel counterparts. In the case of the Abrams, it is like twice as much at the same speed. But they do it because they can't stuff inside a diesel engine powerful enough to move the tank as fast as the turbine can. Same with small light attack ships.
     
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  22. pigpenracing

    pigpenracing Pattern Altitude

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    Talk about impressive! My local buddy I grew up with owns Arrow machine and builds the engines for White Rice.
    It is a Nissan 240SX with a Toyota straight 6.
    85lbs of boost on alcohol.
    This thing went 6.66 at 214 last weekend. It is actually reliable. They got 100 passes out of the last engine before freshining. I have never really cared for imports but this is just bad ass with a inline 6 cylinder!
    Best part this is a 275 radial street tire!
     
    Last edited: Nov 8, 2018
  23. Dan Thomas

    Dan Thomas En-Route

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    Sure you can. One horsepower is 33,000 foot-pounds per minute. If a little jet engine produces the thrust to raise 33 pounds 1000 feet straight up in one minute, it's making one useable HP. That's not taking into account drag losses and so on, of course.
    Here's an article on the HP of a 777's engine: https://www.theatlantic.com/technol...ce-the-horsepower-of-all-the-titanics/250698/

    Turbine makers sometimes rate their HP in shaft-equivalent HP. Torque times RPM of the turbine shaft. Usually applied to turboprops and turboshaft engines.
     
  24. Cap'n Jack

    Cap'n Jack Final Approach

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    Suppose you have a small jet engine that weighs a pound, and produces one pound of thrust. It will just hover if you have it pointing straight up. It isn't lifting anything, and is technically doing no work. But it is producing a pound of thrust. Any more than that, and it will accelerate upwards, ignoring drag losses and so forth.

    In the example of the jet (or a rocket, for that matter) raising 33 pounds straight up, you'll find it is accelerating the whole time. After the first 1000 feet, it is still accelerating- does this mean it's horsepower has increased because it lifts the 33 pounds faster over the second thousand feet?

    That is something entirely different from thrust. Car engines may be rated the same way.
     
  25. benyflyguy

    benyflyguy Line Up and Wait

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    Cool read. What I’d like to know more about is how it got to this point?? Who got the idea to just “pour more fuel in”. “Compress it harder” “what’s more explosive that we can ram in their”.
     
  26. vman

    vman Pre-takeoff checklist

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  27. Dan Thomas

    Dan Thomas En-Route

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    More mistakes. The sparkplug will fire at around 30,000 or 40,000 volts. If that was 30KV at 44 amps, we'd be sending 1.3 million watts to each plug, about the same output from one of those big windmills. You'd turn the engine into molten metal. The primary winding of the coil might be getting 44 amps at 14 volts, which would be a more believable 616 watts. The coil turns that into 30KV but the amperage would drop to around 20 milliamps, still a very hot spark.
     
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