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I'm building a soap box derby car.

Discussion in 'The Lounge' started by hunterguy86, Oct 9, 2006.

  1. hunterguy86

    hunterguy86 1/2 ton status

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    Every year for homecoming we have a soap box derby race at my college. I'm in charge of heading up this project and Id like to win this thing. The cars launch off a ramp thats like 45 degrees. So I'm thinkin it needs good approach and departure angles so it dont drag. I was kinda thinkin maybe retrofitting an old riding lawn mower frame. Bring on the ideas.

    Here are the rules:

    A. Soap Box Derby
    The Homecoming Soap Box Derby is sponsored annually by Order of Omega. The purpose of the event is to promote school spirit and unity among the many organized groups that comprise the Texas State University-San Marcos campus. The teams participating in this event build soapbox derby cars and compete for trophies and points toward the highly coveted Homecoming "Spark Award." The following rules and regulations are designed to provide uniformity of cars for a safe and exciting race.

    1. Width- Overall width of the car cannot exceed 40 inches (102 cm.), wheel to wheel.
    2. Length- Overall length cannot exceed 84 inches (213 cm.).
    3. Wheels and Axle-
    a. The wheels may not be less than 7 inches (18 cm.) in diameter (top to bottom).
    b. The wheels must not exceed 12 inches (30 cm.) in diameter.
    c. The car must run on four wheels. Two front and two rear, as an automobile.
    d. The brakes on the car must be in working order. It is suggested that the nose of the car be built to withstand the impact of several hay bales that will be at the bottom of the hill. Order of Omega will have the right to disqualify any car which brakes are not adequate to stop the car.
    e. The steering on the car must be functional.
    f. An approved motorcycle helmet is required for the driver(s).

    *NOTE: A full effort will be made to remove buses and cars along the soapbox route. Texas State University-San Marcos, its agents, or agencies, or Order of Omega, who acts as sponsors of the Soap Box Derby, shall not be held liable for accidents or injuries resulting from participation in the Soap Box Derby. All drivers must be 18 years or older and must sign the event participation form. A driver who does not sign the participation form will not be eligible for competition. ID's will be checked before the race.
    Each organization will be required to sign a liability waiver to this effect.

    1. Judging- There will be three divisions in the Soap Box Derby:
    " Greek
    " Student Organizations
    " Residence Halls

    2. All participants must check in two hours prior to start of derby to assess that car meets all
    designated specs and requirements
     
  2. ryan22re

    ryan22re 1/2 ton status

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    Let's see, I'd build one that runs on 12 inch bike tires (the smoothest you can find), that's 40 inches wide, 84 inches from the front of the front tire to the back of the back tire. Have the weight distribution about 40/60. Any more weight on the rear will cause it to get loose as it transitions from the starting ramp. You also want to get it to transition from the starting ramp to the track as smooth as possible. That is where you will win the race. Aerodynamics won't play much of a role, but can help. I'd spend as much time as possible making it run straight and transition onto the track as I could.
     
  3. hunterguy86

    hunterguy86 1/2 ton status

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    Thanks for the reply man! Any Ideas as far as how to set up steering?
     
  4. ryan22re

    ryan22re 1/2 ton status

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    Go kart stuff more than likely would be the easiest to find.
     
  5. beater_k20

    beater_k20 Banned

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    how about something like the push pull steering that comes stock on straight axle Chevy trucks? rather than a steering wheel, us a lever to actuate it. bike tires would be best, and make sure to air them a little past their maximum inflation rating. they wont be getting hot, so you wont have to worry about blowing them, and the harder tire will have less rolling resistance.

    the 40/60 weight bias sounds like a decent idea for the transition from the ramp to the racing surface. with the downhill slope your static bias will act more like 50/50 or 60/40 allowing the front of the car to make the transition smoother.
     
  6. TSGB

    TSGB 1 ton status

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    Order of Omega? Are you straight? :thinking:

    :haha:




    That's funny.


    I have nothing useful to contribute to this thread. :(
     
  7. hunterguy86

    hunterguy86 1/2 ton status

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    Hahahahahahahaha. No I'm not gay. Order of Omega is the greek council or some stupid **** like that. They direct the frats and sororities which are totally bogus here. Anyways.

    Thanks for the replies. I've looked at some gokart diagrams and I got some ideas but this project has to be done on the cheap. I'm thinkin if I can find an old riding mower I can adapt that steering to the cart.
     
  8. ryan22re

    ryan22re 1/2 ton status

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    I was thinking, if you could get the car to track straight, steering wouldn't be needed. You could just set up each rear tire with an independant friction brake on the tire, and apply the brake to steer the car. Assuming a straight course. Sure you'd scrub off some speed, but chances are it'd work and be alot cheaper and easier to build.
     
  9. beater_k20

    beater_k20 Banned

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    race + scrub off speed = lose, no good.
     
  10. hunterguy86

    hunterguy86 1/2 ton status

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    I had thought of this to but the rules state that steering is required on the car.
     
  11. beater_k20

    beater_k20 Banned

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    true, they do say that it is required, however it doesnt say by what means the car MUST be steered. i dont see how they could disallow it.
     
  12. hunterguy86

    hunterguy86 1/2 ton status

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    Thats a good point :doah:
     
  13. broke73

    broke73 1/2 ton status

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    Just thought I'd share a little info. One of the software engineers I work with owns this company. He has designed software to run soapbox derby races. Take a look its kinda interesting.

    http://www.packardsoftware.com/index.htm
     

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