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Take a Top Fueller or Funny Car rear end out and replace it with a dual chain drive, directly driving a dual cone rear axle with a diameter of say 1 metre at the centreline of the vehicle, reducing to around 75mm (3in) out towards the wheel hub.
Each side of that centreline the axle tapers away along
a continuous helical path of sprocket tines tightly wound around the axle and leading to a final ring gear at the narrow end. Large springs force a set of chain guides outwards, as the gearing winds out along the axle shaft, maintaining tension on the chain. They also ensure the front end gear helix remains properly engaged.
A first stage reduction gearbox at the front end of the chain ensures there is enough torque in the drivetrain to push everything along at a fair clip. The gearset here is also a spiral, though one that increases in diameter, improving speed at the rear end as it becomes a larger diameter drive gear, driving a rear end of decreasing diameter.
Once you drop the clutch everything erupts in a fury of noise, the big gear getting you off the line quickly, and the constant reduction simply winds up the acceleration at an increasing rate.
Pop the chute and collect the trophy.
Fire up the Chaingine
Chaingine
or not. [rcarty, Feb 17 2008]
Anatomy of a topfuel dragster
http://www.nhraonli...anatomy/topfuel.htm
[Ling, Feb 18 2008]
Annotation:
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Sounds good to me. One thing: why not
use a kevlar belt, wound round around on
itself
like a fire-hose? It would still give you the
progressive reduction in diameter, but
with less hardware. |
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Fair enough. I just went for the frivolously complicated option. |
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that's a heckofalot of mass to be moving. rotational mass especially. i'd be scared to see a chain break. |
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I'd be happy to see a chain break. Bunorama, baby. |
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..and since most of the rules governing competition in these classes relate to the power unit (fuel, supercharging and such) and various safety aspects, halfbaked transmissions would seem to be allowed. |
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If the chain were to reel off kind of like winding up a gyroscope or Top such that the car would get progressively lighter the further down the track it went and laying down a strip of chain as it went. |
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To prepare the car you would have to park at the end of the track and back all the way to the start. |
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I stayed away from the engine and fuel, [CF], for that reason. I'm doing some work for a company that builds drag racing engines at the moment. Man, those guys are passionate about their penis substitution! |
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For a minute I thought this was "Massive Chain-drive Wagster". Which was an interesting thought. |
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This is very close to my first idea and the reason I have this name. Way back before the WWW, AOL used to give free hours to people who would help kids with their homework. To do it you should invent a teacher sounding signon, so I invented MisterQED. I helped some kids with math, but the submissions I loved were science projects/challenges. One that I found a cool solution for was the "mouse trap challenge". I would explain they had two things to worry about, getting the most out of the spring and getting the best gearing for the car. The spring was solved by having it turn a semi-circular pulley and having it then run thru a low pulley on the trap. The second problem was solved by attaching a thin spindle to the rear axis and using ribbon to attach the two together. In that way the stacked ribbon would give you the torque you needed to start and as it unwrapped, the speed to go fast and far. I created a stock email that gave details of construction, leaving just rear wheel size and ribbon thickness as values to be computed by trial and error based on spring force. I must have sent out a hundred of those letters, but today's search showed that no one seems to have listened or if they did, they never caught on. There is a site for the ultimate mouse trap car, that uses neither of my advances. When my daughter gets old enough, I hope she'll humor me and let us enter these contests. I'll ask her as soon as she learns to talk. |
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This is an excellent idea. Chains can transmit high power easily. I think that torque is controlled, off the line, to stop spinning, so UB's cone could be shaped accordingly (small, big, smaller). |
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The single taper would do away with wheelspin in the takeoff stage, I think. Of course, that's down to just how much power the engine develops. |
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In fact, the chains could be simply wound on and then fed to the front of the vehicle as it goes through the acceleration cycle. A pair of hoppers at the front axle would catch the chains, adding weight to the front end for greater stability as speed increases. |
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the way i understand the idea is that there is a spiral and conical sprocket on the engine and axle. the chain would start at the small end of the engine's sprocket and the large end of the axle's sprocket to provide the most torque. it the chain would move to the highest sprocket on the engine and the smallest on the axle for highest top speed. |
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Idea text amended to clarify that point, [crazyrog17]. |
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What if you lost traction? Any loss of traction would leave you revving too low (overgeared) for the remainder of the run and since this system would maintain a fixed engine/roadspeed ratio you would be unable gain any more engine speed without exceeding roadspeed, spinning the gears down even more. |
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If you lose traction mid-run in any dragracer you are toast anyway. |
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No i mean at launch. The degree of wheelspin at launch would determine your final drive ratio for the rest of the race. Remember the optimum change in gear rato is not a linear one but an inverse exponent. a "hot" start would leave you much further down the curve for the rest of the race sorta like being forced to shift early in every gear. |
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That's why we start out at a relatively leisurely rolling pace. The design is such that we don't break traction at all. The car finishes like a rocket, with a straight linear acceleration profile. |
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I think that you would find that those first sixty feet were really, really important. If it doesn't allow for a fast start then the idea is pretty worthless. Remeber the inverse exponential optimum gear curve? That steep part is the most important part. |
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Yes but that's a detail - you can choose any gear ratio curve you like by altering the profile of the rear axle or (if you're using the [Maxwell]/[QED] method) by having a 'ribbon' of varying thickness. |
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Sure, I was just pointing out that wheelspin was going to be the bane of this system (that and making it small enough to be practicable) |
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Exactly. The idea is to get it moving and keep it accelerating. I know that drag cars spin to get off the line. Most of that is for the excitement of the slackjawed yokels who paid to watch you cook some rubber. The rest is to preserve the drivetrain as the massive power of the engine will twist the car into a helix if you don't mitigate the torque, using fixed gear and diff ratios. |
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My idea is to start with very low gearing and ramp it up at an increasing rate. You might observe that 4WD cars, like the Subaru WRX, will get a far faster takeoff than the average knucklehead's pride and joy because they don't spin and slip. |
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You are going to make this 4wd to? Why wouldn't you sart with a high ratio like a normal car and go down like a normal car. From a dead stop a dragster can eat a huge quantity of power launching (Near full engine output) then maintain that output all the way down the track. Keep the engine at peak speed and regulate torque with the throttle not the engine speed. This idea is not as simple as it seems. |
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Did I say that I was going to make it 4WD? I think you're trying hard to be obtuse about this idea, [WcW]. It's just a replacement for a gearbox and diff with a simplified CVT modelled around a rear axle. |
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If you want to go running off on a tangent do it somewhere else. I'm removing the entire tangential discussion, if you continue to labour a point that has been explained to you several times already. |
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I'll ask Michael at Hogg tomorrow, what he thinks of the idea. It's how he makes his living, so he should have a clue. |
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From link: "To prevent a loss of traction, power is transferred from the engine to the rear tires via a complex timer-controlled clutch system. The centrifugal pressure that squeezes the four discs and three steel floater plates together is applied gradually in a series of infinitesimal stages controlled by a hydraulic-fluid-powered throwout bearing and ram until complete one-to-one lockup with the engine and drivetrain is achieved, approximately three seconds into the run. Clutch temperatures can soar to more than 1,000 degrees F. All Top Fuel cars run a standard rear-gear ratio of 3.20-1." |
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//making it small enough to be practicable//
<rising note of hysteria and disbelief>"Practicable"? </rnohad>
You're not from round here, are you [WcW]? |
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The wheelspin is also to heat up the tires. I doubt you would get good traction without it. And if you aren't pushing the limits on breakaway traction then you simply aren't going to win. |
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I see simple spacing problems to be your likely downfall. A belt thick enough to accept the torque would be too thick to wrap and not end up much larger than the tire diameter in order to the length needed for a quarter-mile track. |
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The only big problem I see is tire heat up. You are correct that you don't want tire spin during the race, but you do definitely need it before the race. |
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I thought you got all the tire heating you needed at the pre-race burnout. A proper racer will driver around the wet patch, back into it, do the burnout for tire heating, and then roll up to the staging lights. |
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Some of the track officials right there at the starting zones finish the day in full-body blackface. They are absolutely coated with rubber crumbs. |
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Bun, by the way. This is cool. |
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Absolutely, you need the pre-race burnout. Can you do that with another gear? |
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I dunno. The sort of drive system that works well on a car powered by a spring might not work so well when when attached to a top fuel dragster. Trial by fire yanknow. I didn't say I disliked the idea I just think that there may be some aspects of drag racing that might have been missed. If you had proposed that the car would have a chain system long enough to make a transcontenetal journey then I would have kept my mouth shut. |
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