46u
Pine Head
Posts: 42
|
COG
Feb 19, 2012 19:48:59 GMT -6
Post by 46u on Feb 19, 2012 19:48:59 GMT -6
What affect on the car does changing the COG have. I know most run between 1/2 to 1 inch in front of the rear axle. But what affect does 1/2 have over 1 inch and so on? Thanks Jeff
|
|
|
COG
Feb 20, 2012 5:22:01 GMT -6
Post by renner on Feb 20, 2012 5:22:01 GMT -6
The center of gravity measurement involves a balance between extra potential energy versus stability.
- The farther the weight is toward the back of the car, the higher it sits on the starting line and that potential energy becomes kinetic energy (speed) on the flat part of the track. Speed = Good.
- However, the farther back the weight is, the more it takes the weight off the front wheel(s) and creates an unstable condition, such as the "wobbles". The wobbles are when the car bounces around side to side, hitting the rail, and in extreme cases making the car bounce off the track. Wobbles = Bad.
So the key is to understand the variables of track quality, car construction, etc. to get the most potential energy without getting instability. A well built car on a smooth track can have the weight closer to the rear wheels and be very fast. A car not machined to perfection on a rough wooden track should have the weight more toward the front of the car. In this situation the car would be faster because it stays stable and runs straight down the track without the wobbles.
The best way to decide 1/2" versus 1" is to test your car on the track and see what it does, an option I unfortunately don't have. Without the ability to test, I rely on the experts on this forum for advice.
Hope this helps!
Renner
|
|
46u
Pine Head
Posts: 42
|
COG
Feb 20, 2012 17:58:29 GMT -6
Post by 46u on Feb 20, 2012 17:58:29 GMT -6
Thank you! I did some more research and that is pretty much the conclusion I came to but thanks for confirming it. The car my grandson and I are running now I set at 1 inch do to the fact I only had 3 days to build it. I had to route out a lot of the front to get it that close. I think on our next build I am going to try 3/4 of a inch. Thanks Jeff
|
|
|
COG
Feb 20, 2012 21:50:28 GMT -6
Post by renner on Feb 20, 2012 21:50:28 GMT -6
Here's what I had to do to get one of my cars to a 1" COG. Fortunately it was designed for looks but I still want to see how fast I can make her go. Attachments:
|
|
|
COG
Feb 23, 2012 17:46:19 GMT -6
Post by blizzard on Feb 23, 2012 17:46:19 GMT -6
We cut out everything except for 1/8" around the body and a 1/4" strip for the rear axles. You can move the weight where ever you need it then. We then cover the top and the bottom with 1/64" plywood. Your car should be around .4 oz. This is all good as long as your son doesn't put too much paint on and you get to check in and you are .1 oz over.
|
|
46u
Pine Head
Posts: 42
|
COG
Feb 24, 2012 10:47:27 GMT -6
Post by 46u on Feb 24, 2012 10:47:27 GMT -6
Thanks all this is the results of my grandson and I's effort. Keep in mind this is our first build ever. Round two tomorrow. Thanks Jeff
|
|