Geetting COM Under 1/2" ???

[davidwilkie]

No comments on the merit of a 0.5 COM? If an aluminum track is that not so crazy?

[Scrollsawer]

No comments on the merit of a 0.5 COM? If an aluminum track is that not so crazy?

A 0.5 COM is a great COM for derby builds. I think the COM location is somewhat dependent upon several factors. As long as the metal track has good joint sections, and so long as you've got rears drilled at 5/8", then 3/8" to 1/2" COMS should be okay, provided you can get the weight placed down low, at the axle line of the car. That's why most everyone here favors a Hershey bar shape with a 1/4" car body height (minus veneers or balsa canopies). Keeping all that weight back there, and at the axle line helps keep the car more stable with aggressive COMS like these. The original poster inquired about COM designs that could be than 0.5", thus all the responses to that effect.

[Noskills]

See the Noskills 2015 line up under the photos section. We all had a COM of 0.5. 42 ft best track. I filmed all cars in slo mo and the only one with wobble (and it was more like a few swerves) was mine. So with the right wheelbase and drift the COM of 0.5 can be your friend.
Noskills.

[davidwilkie]

what / where do you mean by "photos section" ?

[Noskills]

I meant the Car and Semi Truck Photo forum. I am using my iPad so could not paste the link but pictures of my family cars are there.
Noskills

[knotthed]

Guys, let's please keep this forum about the kid's races.

gpraceman,

No disrespect, but this is why I don't post much if at all anymore on this forum. I have quite enjoyed this forum and without a doubt it has helped my son and I build better cars. So thank you for operating it.

The fact that you have to have to watch what you say about advanced building and those accompanying experiences is not conducive to helping people when your standing there with a ruler ready to whack someone on the fingers for even mentioning the word L**gue.

While I am not very acitve on any l**gue forums either, much of the advancements in our skills in the last year have come from those places.

It's where cutting edge builds are put to the real life test on a regular basis instead of annually. That then has a trickle down effect into Kid's racing.

I was not even really aware of l**gue racing until we tracked down the fast people from the kid's Mid America race.


For the original poster,

I would not be too concerned with getting the com less than 1/2" as I have been lucky enough to handle some very fast cars from Mid America and they didn't have a com less than 1/2". In fact, I can empirically say the fastest car at Mid America did not have a COM less than 1/2".

Thank goodness for Mid America or I wouldn't be able to relay this information publicly on the forum without getting the ruler on my fingers.

Want to get it under 1/2"? go for it! Use the new wheel weights with some W cubes next to the axles - that should get you under 1/2" with a 1/4" ladder or cutout body.

[gpraceman]

No disrespect, but this is why I don't post much if at all anymore on this forum. I have quite enjoyed this forum and without a doubt it has helped my son and I build better cars. So thank you for operating it.

The fact that you have to have to watch what you say about advanced building and those accompanying experiences is not conducive to helping people when your standing there with a ruler ready to whack someone on the fingers for even mentioning the word L**gue.

While I am not very acitve on any l**gue forums either, much of the advancements in our skills in the last year have come from those places.

It's where cutting edge builds are put to the real life test on a regular basis instead of annually. That then has a trickle down effect into Kid's racing.

I was not even really aware of l**gue racing until we tracked down the fast people from the kid's Mid America race.

You are certainly welcome to your opinion. However, I think it is an inaccurate statement that members here cannot mention the adult leagues. Look around the forum, and you will find mention of building techniques and tools that league racers are employing. However, some discussions I feel are better left off this forum, such as trying to promote racing leagues, which was the reason for my comment in this thread. I have no real issue with racing leagues, but I will continue to try to keep Derby Talk focused on the kids races. That is what I created this forum for in the first place. The leagues have their own forums, where people can discuss joining a league as well the ins and outs of league racing. Some discussions are best done on those forums and not on one centered on kids racing.

[pwrd by tungsten]

No comments on the merit of a 0.5 COM? If an aluminum track is that not so crazy?

Ideal COM is 5/8"-3/4" for someone that know what they are doing. And for someone that does not know what they are doing it is more 7/8"-1"

I have a car that is 3/8" and it is fast but it would be even faster with a more appropriate COM....

[davet]

Our wheelbase is 5.5 and our DFW weight is 61oz with all weight centered on the car. What kind of steer are you guys finding works best for light DFW and long wheelbase for long aluminum tracks?

[Speedster]

I found a car at inspection this year with a 1/4" CM in a stock wheelbase car. It was not intentional. It made it down our wood piantedosi track and took 1st place. I explained the design of the "Best" track to him and urged him to move the CM forward for fear it would not handle the quick curve. I don't know if he did or if he even showed up at the District race. I was there all day in charge of the repair table. I didn't hear about anyone jumping the track. Whether that CM would have stayed on the Best track I will possibly never know unless he shows up for next years race. I question an aggressive CM in a scout race. It's always fun to win but the car has to finish to do that. Is it even a true benefit?

[davet]

Can you put the 12 cubes behind the rear axle then put a plate under the cubes and behind the rear axle? Then add whatever else is needed just ahead of the rear axle. Would this give a low COM even if the body was super thin?

[sporty]

Sure.

The issue going less than 3/8th of a inch. Is it become very hard to control the car. More drift needed. Friction from more drift. Then becomes a factor.

When you start trying to go less than 3/8. The number of people who can do it and go very fast with it. Becomes a very small list.

I recall when I was sharing. Running 3/8. People thought I was crazy.

I tried less. But I could not findining more speed. Myself.

The bigger focus became more weight. Lighter bodies.

My goal was 10 to 12 grams.

Now people are running 5 to 7 gram cars.

To get more weight concentration. Not so much farther back weight placement.

[Stan Pope]

Can you put the 12 cubes behind the rear axle then put a plate under the cubes and behind the rear axle? Then add whatever else is needed just ahead of the rear axle. Would this give a low COM even if the body was super thin?

That sounds like a lot of mass behind the rear axle, but might be needed if the front part of the car is "bulky." However, I don't see a "super thin body" as "bulky".

[davet]

I was wondering about it because we got beat this year by the annual Pack winner. He has some kind of very shallow spoiler at the back of his car. It was like the body just swooped up in the rear. I thought maybe he had stacked some weights somehow behind the rear axle.
We had track record this yr until his heat and he beat us by .04 seconds.

[Stan Pope]

This could be due to his new secret lubricant, one with a coefficient of friction of about -0.02 or so.

Ummm... sorry, 13 days too early.