Centre of gravity
 

Hey guys I'm making up a custom 4 link setup on one of my rigs and I need to work out how high up the chassis the centre of gravity is. With out some idea it's going to be impossible to calculate the anti squat. ATM I just need a rough calculation to use as base line, then I can mount it up and test from there and adjust if required.

So far... The only way I can think of is literally balance the car on one end with my finger like a circus freak untill I find the sweet spot that's easy to balance. Then simply mark it, then sit the vehicle down level at a static ride hight and measure the distance from that mark to the ground..... Only problem... I'm scared I might drop it as its 1/6 scale.

if anyone has any ideas to measure the COG please I'm all ears.

What does it weigh? I have a thought, but your vehicle may crush the setup/measuring tool.

Here's one option:

http://www.wikihow.com/Calculate-Center-of-Gravity

Or, my thought (With a stronger version design) would be:

http://www.rcuniverse.com/forum/atta...mentid=1952150

This is what the RC plane guys use. I figure you can do the same with some metal rods and a 2x4, only put the metal rods closer together than what's above. Having two rods stabilizes the weight from side to side. Then you just put your truck on top of the two rod ends that are sticking up, and move the setup front to back on the bottom of the truck until you find a spot where the truck is pretty close to be exactly balanced on the rod ends. Where the rod ends are located at this point is where the center of gravity is.

The setups are very easy to make. Simply drill holes in your wood piece that are 1/1000" or 2/1000" smaller than the diameter of the rods that you'll be using. Measure out the distance between the holes, so that the rod ends will fit nicely in the desired location of measuring point within the chassis (Or whatever) BEFORE drilling. Be sure to drill the holes the same depth (Or all the way through, and glue them flush with the bottom of the board) or the ends of the rods won't be the same height when in there. Put a dab of all purpose glue (Or glue that sticks to metal and wood. (Or whatever materials that your using.) in the holes. Use a small rubber mallet or the like and pound the rods into the holes until they bottom out. (Or go all the way through.) Let them dry. (Be sure that if you did the 'drill all the way through procedure', that the rod ends that are in the holes in the wood are flush with the bottom of the wood board.) Simple as that! ;)

I realize these are detailed instructions (and way too easy for you to handle), but if someone else is wondering how, then this will be a good reference....

I do recommend using something wider than a 2x4, because with the weight of a 1/6 scale, it may not be very stable while your trying to measure it.

cheerz bud.... That's a awesome method and thank you for the reply. but... that will only give me horizontal COG where I need the vertical COG :(

tis might clear things up (NOT MY PIC)
see the horizontal green line? that represents the vertical GOG

http://www.fototime.com/%7B488C5668-...7D/picture.JPG

and the red line is the 100% antisquat force line its drawn from the base of the rear wheels up to where the COG and the front force line cross over.

Finding the center of mass can be fairly simple (center of gravity).

Step 1 is to tie your suspension to your desired ride height so it doesn't move when you pick up the truck.

Step 2 is to tie a string or chord to the front of the chassis and hang it still in the air. The center of gravity will always be directly below the string put a piece of tape on the side of the chassis and draw a vertical line like you are extending the string.

Step 3 is to hang the truck with a string tied to the top of the chassis and draw a line extending the string through the chassis.

Where these 2 lines intersect is your center of gravity.

Ahhh I'm with ya.... So I hang the truck from say the front untill it looks like its hanging straight down then mark.....


thankyou thankyou thankyou

Exactly. The cog will always be in line with the string. By hanging it twice from 2 separate parts of the truck, you will get two intersecting lines (crossing lines for those that English is not their primary language). Where they cross is your cog

just be sure to lock your suspension to your desired ride height and add your batteries, body, etc

legend.... thankyou. That makes perfect sence....

well looks like ive got some more work to do before I can calculate the COG, Im still yet to make the cross braces and battery tray...