Critiquing a critique of rail riding.

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tmack
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Re: Critiquing a critique of rail riding.

Post by tmack »

Stan Pope wrote: Now, with rail guiding more commonly used, it is not unreasonable for such a car to finish 3rd ... behind two other rail guided cars!
Ha! Very true Stan, but its easier on my ego if I blame the track. How dare someone else make a rr! :burningmad:
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Re: Critiquing a critique of rail riding.

Post by DerbyAddicted »

Stan Pope wrote:If the car does not fly up out of its lane, then I think that rail guided car will outperform straight alignment ... IF the toe-in is in the ballpark of right and if positive camber is employed. However, if there are deep gouges in the rail that the DFW can ride up on, then the car can, perhaps consistently, fly up and crash. Most of us avoid employing such tracks, but sometimes there is no alternative.

Now, with rail guiding more commonly used, it is not unreasonable for such a car to finish 3rd ... behind two other rail guided cars! The rail guiding practice is not new. It was not new in the 1980's when I overheard a couple of old timers commenting, "That car needs more toe-in!" But is was a much more closely held secret back then.
I'm a rookie, but I think that if you could get car perfectly aligned to go perfectly straight, and NEVER touch the rail, it would out perform a RR. But that's the problem. I don't think you can guarantee that a car will be perfectly aligned and not touch the rail, so I think RR is assuming you're going to hit the rail, and turning it into a positive by tuning and preparing for it.
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Vitamin K
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Re: Critiquing a critique of rail riding.

Post by Vitamin K »

Considering that the car starts with, what, half an inch of space between each wheel and the rail, and has to travel 32 to 40 feet, you'd have to have some amazing alignment not to have a drift of half an inch or more throughout the race. Not even taking into account factors like minute track irregularities, levelling issues and, of course, how accurately the car was staged to begin with.

So yeah, if you could somehow guarantee that the car would never touch the rail ever, you'd be faster, but that's hard to conceive in the real world.

OTOH: One of the other threads seemed to indicate a theoretical alignment setup for where a car would lightly 'skim' the rail, with very slow drifts to and fro, as opposed to a rapid oscillation down the track. That might be worth investigating/experimenting?
DerbyAddicted wrote: I'm a rookie, but I think that if you could get car perfectly aligned to go perfectly straight, and NEVER touch the rail, it would out perform a RR. But that's the problem. I don't think you can guarantee that a car will be perfectly aligned and not touch the rail, so I think RR is assuming you're going to hit the rail, and turning it into a positive by tuning and preparing for it.
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Stan Pope
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Re: Critiquing a critique of rail riding.

Post by Stan Pope »

DerbyAddicted wrote:I'm a rookie, but I think that if you could get car perfectly aligned to go perfectly straight, and NEVER touch the rail, it would out perform a RR. But that's the problem.
I have produced some of the most perfectly "straight aligned" cars (i.e. 0.0 toe and 0.0 camber all around) ever, but none ever made it to the 28' finish line without banging the rail! (I documented the alignment process and made it available for free to everyone with an internet connection a bunch of years ago. I've heard it called "shim alignment", but the most important feature was the alignment measuring concept, part of which is retained in different form in my most recent alignment contribution involving "weight bias alignment".)

Back when I was young and foolish (should that be "younger and foolisher"?), I worked with 15 of my pack's 16 possible district derby entrants (top 4 in each rank) to straight-align whatever car they made. The pack's results went way up from prior years (three first place trophies, of a possible four, a third, and all in the entrants were in the top quarter), but they still got "blown away" in the race of rank winners by a car that went straight down the track just like it knew where it needed to go. Anybody think that it wasn't rail guided? I did that one year and decided "I should never do that again."
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davet
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Re: Critiquing a critique of rail riding.

Post by davet »

LightninBoy wrote: He also didn't say whether he was using negative or positive cant on the DFW.
Just when I thought I was getting all of the puzzle pieces at least facing up prior to trying to fit them together you throw this in there. I thought the DFW always gets negative cant to prevent the inside edge of the wheel from catching a seam at the top of the center rail. Is there talk of running positive cant on DFW?
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Re: Critiquing a critique of rail riding.

Post by Speedster »

Negative cant has the top of the wheel leaning toward the car. Positive cant has the top of the wheel leaning away from the car. Positive cant will keep the wheel from catching a misaligned track section.
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davet
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Re: Critiquing a critique of rail riding.

Post by davet »

Copy that. Had them mixed up I guess. When would u want to tip the top out?
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Re: Critiquing a critique of rail riding.

Post by LightninBoy »

davet wrote:When would u want to tip the top out?
Positive cant (tip the top of the wheel out) is preferred on the DFW.
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Curse You Red Baron!
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Re: Critiquing a critique of rail riding.

Post by Curse You Red Baron! »

Stan Pope wrote:
If the car does not fly up out of its lane, then I think that rail guided car will outperform straight alignment ... IF the toe-in is in the ballpark of right and if positive camber is employed. However, if there are deep gouges in the rail that the DFW can ride up on, then the car can, perhaps consistently, fly up and crash. Most of us avoid employing such tracks, but sometimes there is no alternative.

Now, with rail guiding more commonly used, it is not unreasonable for such a car to finish 3rd ... behind two other rail guided cars! The rail guiding practice is not new. It was not new in the 1980's when I overheard a couple of old timers commenting, "That car needs more toe-in!" But is was a much more closely held secret back then.


Last year my son did a rail-rider (4 on the floor, per Pack rules) that launched a foot or so before the finish line and crossed it in mid-air. Very cool video. Happened twice. Still won every race handily. The competition was good, but that car was smokin'. RR definitely was part of the reason, it really outperformed on the straight-away.
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