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Acceleration Program

970 views 2 replies 1 participant last post by  BillyShope 
#1 · (Edited)
There's an old joke about the fellow that was so egotistical that he thought he made only one mistake last year and that was when he thought he had made a mistake. Well, maybe I know how he felt. I changed the attached file yesterday because I thought I had made a mistake. Now, it seems that my mistake was when I keyed in some incorrect data while I was running it. So, in making the program match my typo, I introduced a bug into the program. In short, the program was correct initially and my "fix" yesterday was a mistake. So, the attached file is the original, but with the addition of the calculation of zero to 60 times. Hopefully, that's it and I apologize to those who have been trying to make yesterday's file work. (To compound my error, I neglected to change the name on yesterday's file, so there are "good" and "bad" programs floating around out there with the same name.)

Hope this works. The attachment to this post is an acceleration program I've written in HTML/JavaScript. This would mean that it normally has an ".htm" extension, which isn't acceptable as an attachment at this site. So, I've "cheated" and saved it with a ".txt" extension. Hopefully, you can open it in NotePad, save it, rename it with the ".htm" extension, and then open it in your Internet browser.

There's no fancy animation or sounds, so it should work in any browser. If you have a problem, let me know.

The primary use for the program is to investigate various "what if"'s. You don't have to input all the data each time. If you want to change axle ratio, just do it and hit the "Display" button again.

The program uses a "typical" torque curve which is "skewed" and factored to match the input. Rear wheel horsepower is calculated from this curve. Flywheel horsepower is calculated using a relationship between quarter mile speed and weight which was developed by Chrysler's George Wallace back in the fifties. The force required data is for a '60 Valiant. The "equivalent mass" is calculated for each gear, which takes into account the rotating inertia. Tire growth with speed isn't taken into account, but this is normally negligible with radial tires. Output includes 60 foot time, eighth mile, and quarter mile performance.

Have fun!
 

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#3 · (Edited)
Please disregard this post. I've gone back to the original post and replaced the attachment with one that is corrected to remove the bug described here. Hope there's no confusion. The new file also calculates zero to 60 time.

Don't know if this is worth the effort, since there seems to be little interest in this sort of thing, but I did find a "bug" in the program.

When calculating the rear wheel horsepower, I neglected to take into account the "skewing" of the internal torque curve which occurs when you put in the rpm for the maximum torque. So long as that happens to be 3200, you're ok, but, for any other number, the rear wheel horsepower figure will be wrong.

You can either ignore the rear wheel horsepower figure or make the following correction. Click on "view" and "source." About 3/4 of the way down, buried in a bunch of calculations, you'll find the number 4.755

(Actually, the number appears twice. You want to make the following change at the first appearance. At the second appearance, the number is followed by *nt/3.2)

Immediately after that number, type in:

*nt/3200 and "save."

That will skew the horsepower appropriately and your rear wheel horsepower figure will be correct.

Also, make certain that your maximum engine rpm is greater than that associated with the horsepower peak or you'll get an error message.

Sorry about my screwup.
 
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