Determining Center of Gravity

[flowingmotion]

How is everyone figuring out where their center of gravity is?

To determine the weight bias from front to back is simple enough but I'm having trouble measuring where the COG is between the top of the of the vehicle and the ground.

In other words, looking at the car sideways, I can find the COG between east and west but how to you figure out the north and south spot?

To figure out the weight distribution on the horizontal plane, I can put the front wheels on the scale, then the back to determine the ratio. I can repeat that for each side of the vehicle. I can also set the skidplate on a nail and balance it out to find teh exact center point. I can't figure out how to do the same things with the car flipped on it's side. I could attach a piece of lexan to the side of the chassis to give me something to balance on but I think that may mess with the result. Any thoughts?

[kennyj]

Sorry for not being able to find it, but RC Crawler magazine had an article about this. It has to do with hanging your crawler from a string. First from the front bumper, then from the rear bumper. It is pretty easy, if you can find the article.

[JeremyH]

I would do it this way.....find the horizontal center of gravity using the pointed object like you mentioned. Mark this point as a line on the side of your crawler (you might have to remove the body for this which would throw off your results slightly)....then use that same pointed object and lay the crawler on its side and move it up and down along that line until it balances properly. The intersection of these two lines should give you the center of gravity of the truck.

[TSK]

It's simple as following this easy to understand chart.



But it'd probably be helpful to read the rest of the associated material found here.

[flowingmotion]

Originally Posted by JeremyH

I would do it this way.....find the horizontal center of gravity using the pointed object like you mentioned. Mark this point as a line on the side of your crawler (you might have to remove the body for this which would throw off your results slightly)....then use that same pointed object and lay the crawler on its side and move it up and down along that line until it balances properly. The intersection of these two lines should give you the center of gravity of the truck.

That's what I was thinking but the COG is below the skid so there is nothing but air to balance it on.

[flowingmotion]

Originally Posted by TheSCorpionKing

It's simple as following this easy to understand chart.



But it'd probably be helpful to read the rest of the associated material found here.

Gee that chart is helpful. According to my calculations the COG is somewhere near Uranis.

Of course once you read the article the string method is exaclty what i was looking for. Thanks!

[helhedded]

front to rear balance point thread

[JeremyH]

Originally Posted by flowingmotion

That's what I was thinking but the COG is below the skid so there is nothing but air to balance it on.

Oh.....that is true. I didnt think of that...haha!

[solomon7]

This calculator is pretty neat. CG, anti squat, instant center, roll center, etc.
Even has roll over angles.
Just add a 0 to all measurements to make it work correctly.
http://mysite.verizon.net/triaged/4l...tml/index.html

[flowingmotion]

Originally Posted by solomon7

This calculator is pretty neat. CG, anti squat, instant center, roll center, etc.
Even has roll over angles.
Just add a 0 to all measurements to make it work correctly.
http://mysite.verizon.net/triaged/4l...tml/index.html

That's what I'm using. The excel version. I'm trying to get my vehicle CG height.

[TSK]

Originally Posted by flowingmotion

That's what I'm using. The excel version. I'm trying to get my vehicle CG height.

I can find that for you. just give me a snorkel, an apple, and some tin foil.

[Terranaut]

The string method is simple enough, just remember to tie the suspension in it's normal 'at rest' position when you hang ya rig. Otherwise you will get a false result when the springs extend.

Cheers.