FASCAR SPEED SECRETS.
Information provided (copied or plagiarized) directly from www.indyproducts.com
Actually this applies to Pinewood Derby, Indy-UN-500, Shape "N Race , Banana racing or any other down hill racing you can imagine.
FIRST RULE: The car must run in a straight line
This should be pretty obvious but
the trick is how do it.
The fundamental requirements are:
The axles must be parallel within .001 inches per inch of length.
The wheels must all be the same diameter so that each wheel carries its' proportionate share of the car weight.
Each wheel must offer the same resistance to rolling friction. Friction comes from contact of the wheel rim with the track surface, as well as sliding friction between the axle and the wheel bearing surface. (more about this later when I discuss lubrication
Each wheel must possess the same rotational moment of inertia. ( Gee , I hope this does not sound too much like a physics lesson.)
What this means is that a certain
amount of energy is needed to accelerate the rotation of a wheel from zero
revolutions per minute to top speed. If this is different from one wheel to
another then the car will tend to turn toward the side with the more massive
wheel. Normally this is not a problem, as long as the wheels are manufactured
with care. This is one reason that Indy Kit and FASCAR Kit Wheels are all
machined after molding to remove mold flash and produce a consistent uniform
size, mass and tread shape.
SECOND RULE Practice makes perfect (Time Trials)
Any one that has participated in a race like this will tell you that if you have a track with more than one lane, there will be differences in times for each lane. Even with Indy Products Tracks, this will be true (although to a lesser extent). It is important that the DRIVER of the car learn the characteristics of the car and each lane so that he or she can place the car at the starting line for best performance.
If at all possible, set your track up well in advance of the event, and encourage your members to bring the children in for practice. At the same time discourage parents form practicing without the children's participation. This relates to the way you conduct your event. I encourage you to structure the event to maximize the children's participation. After weigh in, you will probably want to place the cars in an impound area so that they can not be accidentally damaged by others. However for each race you should return the car to the child (DRIVER) for placement on the starting line. After the heat the DRIVER should return the car to the steward to safeguard until the next heat. O.K. maybe this isn't a secret but this gives the children a greater hand in the outcome of the race. ( Good training right?)
THIRD RULE Weight Placement is Important
I am sure you already guessed this --- but where and why!!!
First a review of some basic
The "engine " that makes the car go down the track is a thing called POTENTIAL ENERGY. This is something that a mass possesses by virtue of its elevation above the ground (or floor if you wish). That is to say the energy results in the work required to raise a mass a certain distance above the floor.
Potential Energy = Mass of the car X distance above floor.
Needless to say, the car with the greatest potential energy will achieve the greatest speed.
All objects exhibit size and shape as well as mass. What is assumed in the above calculation is that the distance above the floor is the distance to the center of gravity of the object or car.
Nearly all rules have a maximum weight rule for all cars. Therefore it is important that your car be weighted to the maximum amount. It is a good idea for the program to make available , to participants, the official scales well in advance of the event. You should bring your car to a weight that is slightly less than allowed, and be prepared to add a small amount at check in. The small additions can be in the form of strips of tape or coins taped to the car to achieve maximum mass.
This is important but it still
does not say where to place the weight. Since all the cars will be at the
same mass, the only thing you can do is to place the center of gravity as far up
the incline as you can.
Imagine two cars, one with the mass concentrated at the front of the car, and another with the mass concentrated at the rear of the car. Place both cars on the incline at the same point and calculate the potential energy for each car. You will see that the car with the mass concentrated near the rear will possess the greater potential energy.
Don't get carried away with this. If you place the mass behind the rear axle, the front of the car will lift and the car will not run straight.
FOURTH RULE What you use to lubricate the wheels is important.
The rule here is that there is no "pat" answer, but there are some basic principles. In my experience liquid lubricants work better than dry lubricants with the following qualifications. Lubricant viscosity is important. (water is low viscosity and grease is high viscosity). When the wheel rotates on the axle, anything that is contained in the annular space between the wheel and the axle must be sheared. This shearing action absorbs energy. High viscosity materials require more energy to shear them than low viscosity materials. Therefore materials that are water like in viscosity will be best. The second thing to remember is that if the annular space is completely filled with liquid the shear area is greater than if the space is only partly filled. Therefore a small amount of "oil" is better than a large amount of oil. Combinations of lubricants seem to work very well. As an example if you put a petroleum based lubricant on one surface and a silicone based lubricant on another surface you can obtain very low friction coefficients. The same rule applies about amount of lubricant. The best condition is to obtain a mono- molecular film of the two materials on each surface with little or no liquid. You will have to experiment a bit to find lubricants that will not evaporate and last through the race. Some kits use wheels made of a plastic that is not resistant to many oils and greases. Indy Products car kits use a plastic material for the wheels that is resistant to most liquids that you could use for lubricants. Be sure to check, or if you do not know--- Send an e-mail to firstname.lastname@example.org. My best advise is to experiment with various materials to arrive at the best combination ( of course with your children involved). What a good way to teach them experimental principles and techniques.
Good luck and have fun!!
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photos of FasCar races check out: