can someone explain what the pendulum effect means my weight is mounted behind the axle and was told to move it forward
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can someone explain what the pendulum effect means my weight is mounted behind the axle and was told to move it forward
if you have your wt to fare back behind the axle it will swing the backend of the car around giving a false loose fill and over powering the rr tire costing you side bite. this is one reason fuel cells have foam in the to help keep the fuel from moving aound in the tank causing pretty much the same problem.
leaf spring car's aren't as effected by this as bar cars I've seen fast leaf car's with wt mounted in front of the rear bumper.
Works similar to a pendulum in a clock. Excess rear wt can swing the rear of the car during rotation. Add low rear air pressure and the effect can be magnified. It can help a setup, it can also kill a good one.
Interesting thread.
I can see where if the principle is understood then it can be a useful advantage when setting up and driving the car, especially on dirt.
Riddle me this, though, boys. On pavement cars, not factoring in the convenience factor, why isn't there a greater effort to install fuel cells ahead of the rear axel? I haven't really thought this through yet but I've got a couple of ideas in mind.
And this isn't the first time I've thought about this. It's been in consideration, but on the back burner of my mind, for several years.
Happy Racing!
Most rule books say must be mounted behind axle centerline
Its not as big a deal on pavement, you dont sling a car or slide a car on pavement.
I mounted my cell over the top of my axle, it was deemed illegal and now theres a rule that it cant be further forward than xxx.
Foam is in case the cell ruptures so fuel doesnt go all over it helps to contain it.. drop a sponge on the floor and notice small wet area. pour a cup of water on the ground and notice it splatter all over.. that is what foam is for.
ther has been an effort in the dirt lm ranks in the last few years to push the fuel cell forward and to the left some have even had special cells made to fit ther chassis running the price way up.
Yes pavement cars 15 years ago started running cells shaped to fit around the quick change as close as possible.Quote:
Originally Posted by racin6mod
from the fuel safe web site.
What is a Fuel Safe Safety Fuel Cell?
Safety Fuel Cells were developed in the 1960s for race cars that, until their advent, had no protection in a crash from a fuel fed fire. Since Fuel Cells were first used the driver’s odds of survival, in a crash, have been greatly increased. A Safety Fuel Cell consists of four main component parts that in total give the vital protection necessary in today’s competitive high speed racing.
The Cell starts with a bladder (bag tank) which is the core of the system. The bladder is the flexible, extremely strong, fuel container that prevents fuel spillage in the event of an accident. Made from high tensile strength elastomeric components and engineered to withstand the fuel’s chemical attack, the bladder is the first line of defense in a crash.
Foam Baffling inside the bladder has several functions. While displacing a very small amount of fuel, the Foam prevents sloshing of the fuel. By preventing sloshing the Foam keeps the fuel de-aerated which improves fuel delivery and also insures constant delivery of fuel to the pickup. A secondary benefit the foam affords is its ability to prevent flash back explosions. And finally the foam holds the bladder in shape, important with a flexible bladder.
The Fill Plate provides the opening to fill the Cell. It usually contains the fittings for the vent, outlet and return. This important component provides no-spill rollover protection while being engineered to integrate with the bladder for the maximum strength and security.
The final component is the container (can). This part protects the bladder and provides a way to mount the Fuel Cell in the car. Containers have been made from aluminum, steel, carbon fiber, fiberglass or even a cavity in the body structure. Containers are designed to fit the bladder closely and provide maximum capacity.
just to clear up why the foam is in the cell and the many reason's it's ther.
hold a bowling ball, or something heavy at arm's length from your body...spin as fast as you can, then stop your body's spinning as fast as possible....observe what the bowling balls does....
now, hold the same bowling ball in tightly against your chest and repeat the experiment. The outcome will be a bit different...same thing applies to your race car and ballast placement. It's all about inertia, and the effects of how far from a centerline an object with mass is located.
Granted the cell would work the car in front of the axle. But that is where things that rotate are much closer and can cause impact and ignition from contact and its closer to the driver. That aint cool either!
One problem with the bowling ball, it's not touching the ground like added weight would in the car. When it's in the air there is no friction trying to slow it down.
Good reading.
http://www.auto-ware.com/autoware-bi...e.pl?read=4652
Why isn't leaf cars effected as much as bar cars??? Suspension don't dictate how much g-force you have in the turns. Just wondering.Quote:
Originally Posted by racin6mod
point taken to some degree on the bowling ball. And, that is a pretty good article. However to better illustrate my point, and acknowledge negligence of surface friction coefficient presented in my first example, I'll revise my suggested experiment to the following. Sit on the approach at the bowling alley. The surface is slick. Now start with bowling ball in close to your body, accelerate it as quickly as possible, then see how fast you can stop the ball as it slides across the approach. Next, hold it as far away from the body as possible, while still having its weight resting on the approach. Or, have someone roll a ball to you where there is a short radius from the center of your body to the path that the ball is rolling on, and then repeat the procedure where the radius from the center of your body to the ball's path is greater. It will be harder to slow down / stop with it farther away from your body, despite the fact that it is touching the ground and is under the influence of at least some frictional coefficient. Lengthening moment arms will almost always increase leverage of the item at hand on the system as a whole. Therefore, regardless of the system, adding significant amounts of mass to the polar extremities will create a pendulum effect.
Hopefully that makes sense, and serves as a better comparison. ;)
Leaf cars are sprung at the rear shackles. Coil cars are sprung at the rear end and so putting the weight at the back bumper on a coil car puts the weight way farther back in relation to the spring baseQuote:
Originally Posted by Dirtrunner35